Research ArticleSex Ratio Estimations of Loggerhead Sea Turtle Hatchlings atKuriat Islands Tunisia Can Minor Nesting Sites Contribute toCompensate Globally Female-Biased Sex Ratio
Imed Jribi1 and Mohamed Nejmeddine Bradai2
1 Sfax Faculty of Sciences University of Sfax PO Box 1171 3000 Sfax Tunisia2 National Institute of Sea Sciences and Technologies 3000 Sfax Tunisia
Correspondence should be addressed to Imed Jribi imedjribifssrnutn
Received 13 July 2014 Accepted 8 September 2014 Published 14 October 2014
Academic Editor Veronique Martin-Jezequel
Copyright copy 2014 I Jribi and M N Bradai This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
Hatchling sex ratios in the loggerhead turtle Caretta caretta were estimated by placing electronic temperature recorders in sevennests at Kuriat islands (Tunisia) during the 2013 nesting season Based on the mean temperatures during the middle third of theincubation period and on incubation duration the sex ratio of hatchlings at Kuriat islands was highly male-biased Presently themajority of hatchling sex ratio studies are focused on major nesting areas whereby the sex ratios are universally believed to beheavily female-biased Here we present findings from a minor nesting site in the Mediterranean where the hatchling sex ratio wasfound to be male-biased suggesting a potential difference between major and minor nesting sites
1 Introduction
Evolutionary theory [1] suggests that male and female off-spring should be produced in equal proportions (Fisherianequilibrium)There should be selective pressure for this to bethe case because if one sex became rarer that sex would haveproportionally more opportunities to reproduce and wouldtherefore contribute a higher proportion of offspring to thegene pool The benefit of being the rarer sex should con-tinue until the sex ratio reaches 1 1 an ldquoevolutionary stablestrategyrdquo [2] ldquoFisherianrdquo equilibrium however includes thetotal parentrsquos investment until the end of the parental careperiod In sea turtles the parental care ends at the egg layingphase which means that determination of sex ratio is largelycontrolled by environmental parameters including the nesttemperature
Sex determination is the initial event in which undiffer-entiated gonads opt for either ovarian or testicular differen-tiation This process in most vertebrate species is genotypic(GSD for genotypic sex determination) leaving little scopefor deviation from a balanced primary sex ratio [3]
Sea turtles likemany othermembers of theClass Reptiliapossess temperature-dependent sex determination or TSD(reviewed by Mrosovsky [4]) Research has indicated thatsexual differentiation in TSD species is determined by thetemperature at which the eggs are incubated the crucialperiod being the approximate middle third of development[5 6] The point at which a balanced sex ratio occurs isknown as the pivotal temperature more females result fromtemperatures above the pivotal temperature and more malesfrom cooler temperatures (see [7] for a review)
TSD is an important factor to consider in the conserva-tion of the sea turtle species Not only does this aspect of theirdevelopment affect the natural populations but should bean important consideration when designing nest relocationand hatchery programs It is imperative that an accurate andnonlethal sexing technique is developed so that sex ratios canbe monitored in conservation programs [8]
The determination of sex and hence the sex ratio ofhatchlings are very significant basic information in marineturtle population dynamics [3 9 10] It should therefore betaken into account in any conservation planning of nesting
Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 419410 8 pageshttpdxdoiorg1011552014419410
2 The Scientific World Journal
beaches in order to conserve the ldquopopulationrsquos sexual struc-turerdquo and act in an appropriate manner for the protection ofthese endangered reptiles especially in the context of currentglobal warming [11 12] Indeed in species with TSD the sex-determining pathway is extremely sensitive to temperature[13] The transitional range of temperature within which thecomplement of offspring sex shifts from 100 male to 100female (or vice versa) is generally less than 2∘C and may beless than 1∘C [14] while the mean warming predicted on ascale of 100 years is 2∘C [15]
Investigations of the sex ratio of all three classes ofloggerhead turtles (hatchlings juveniles and adults) havesuggested prioritizing the study of the ecological effects ofanthropogenic climate change on marine turtles [10] Suchstudies have recently begun in the Mediterranean regionbut the results cannot yet be considered conclusive at theregional population scale [9] The loggerhead hatchling sexratios are estimated to be female-biased on most beaches inthe Mediterranean [16ndash20] in contrast with more balancedsex ratios in adult and juvenile [21]
Among the worldrsquos seven marine turtle species threespecies are regularly observed in the Mediterranean theloggerhead turtle Caretta caretta the green turtle Cheloniamydas and the leatherback turtle Dermochelys coriacea
All three marine turtle species mentioned were reportedin Tunisian waters but only the loggerhead turtle is a nestingspecies on some beaches [22ndash24] Nesting activity in Tunisiawas mentioned in the literature but not based on systematicsurveys [25ndash27]The nesting of the loggerhead turtle (Carettacaretta) was first recorded in 1988 on the beach situatedbetween Ras Dimas and Mahdia and on the island GreatKuriat [28] the latter of which is considered as the mostimportant nesting site in the country [23 24] Few nests weresometimes laid in other beaches along the Tunisian coasts butthe nesting is not regularly observed
Since 1997 the beaches of both Great and Small Kuriatislands have been monitored to study nesting density andprotect nests nesting females and hatchlings and to deter-mine reproductive parameters Despite the importance of theKuriat islands in Tunisia their beaches should be consideredas minor Mediterranean nesting sites for the loggerheadturtle
Studies of hatchlings sex-ratio in the Mediterraneanconcerned mainly major nesting sites such as Zakynthos [3]and Kyparissia Bay [29 30] in Greece Alagadi in Cyprus[16] Fethiye [31] Patara beaches [17] in Turkey Sirte in Libya[19] but few studies have been conducted for minor nestingsites such as Sicily in Italy [32] The protection and the studyof these minor nesting sites are informative because theycan give an appreciable contribution to sea turtle biologyboth in number and in genetic diversity [24] Moreoverminor site studies may also reveal novel sex-ratio data fortheMediterranean suggesting amuch less female-biased ratiothan previously believed
Recalling the articles of the SPA protocol and the revisedaction plan on marine turtles in the Mediterranean [33]taking into account the new developments concerning con-servation measures based on scientific groundwork andconsidering the potential effects of global warming on future
population structure and on the dynamics of these endan-gered species [11 12] the present study aimed to providedata on hatchling sex ratio estimation from beaches of Greatand Small Kuriat which are the most important nestinggrounds for loggerhead turtles in Tunisia Since the sex ofmarine turtle hatchlings cannot be assessed from externalmorphology as it needs direct observation of the gonadswhich imply to kill the individuals and since sacrificinghatchlings was not an option for ethical and conservationreasons we used incubation duration of clutches and themean temperatures during themiddle third of the incubationperiod as indirectmethods for predicting the sex ratioswithinthe nests
2 Material and Methods
The Tunisian coast spans approximately 1200 km represent-ing about 25 of the coasts of the Mediterranean (about46000 km) [34] In the north most of coasts are rocky whilein the centre and in the south the coasts are mostly sandywith a very large continental shelf in the Gulf of Gabes
The Kuriat islands are situated in the centre of Tunisia(Figure 1) (35∘ 481015840 0510158401015840 N 11∘ 021015840 0510158401015840 E) and lie 18 km from thecoast ofMonastirThey consist of two small islands the SmallKuriat (Kuria Sgira) which is ca 07 km2 and the Great Kuriat(Kuria Kbira) which is ca 27 km2 in area Small Kuriat has atotal of 1500m of sandy beach situated in the north-easternand east parts of the island whereas the rest of the coastlineis rocky or marshy Almost one-third of the Great Kuriatshoreline is rocky and large deposits of sea grass Posidoniaoceanica and detritus further restrict the accessible nestingsites particularly in the south and the south-western beachesThe principal nesting beach lies on the western and southerncoast and it is almost 3000m in length
The nesting season in Kuriat islands generally starts atthe beginning of June and ends at the middle of AugustDeposition of nests occurred in June and mainly in Julywhereas nesting in August remains rare [24] The fieldworkwas conducted during the summer months of 2013 on thebeaches of bothGreat and Small Kuriat Nesting and hatchingactivity were observed over the beaches as part of the long-term monitoring undertaken by the Tunisian Sea Turtle Pro-gramme (TunSTP) since 1997 following a convention signedevery year between the National Institute of Sea Sciencesand Technologies (INSTM) the Regional Activity Centrefor Specially Protected Areas (RACSPA) and the Agencyof Protection and Management of the Littoral (APAL) Thebeach is surveyed throughout the nesting season on bothislands A teamof three to four persons (researchers studentsand volunteers) is permanently present during the season inorder to record female laying or hatchlings emergence datesEach nest was located bywalking on the beach and the preciseGPS position was recorded in order to locate the nest andidentify its first hatchling emergence date For the purpose ofthis study incubation duration is defined as the period in daysbetween observation of the newly laid nest and the first recordof emergence by either direct observation of hatchlings ortheir crawl tracks emerging from nests
The Scientific World Journal 3
45
40
35
30
35302520151050-5
Gulf of Hammemet
Tunisia
10km
Kuriat islands
10∘00
99840010
∘20
99840010
∘40
99840011
∘00
99840011
∘20
99840011
∘40
99840012
∘00
998400
37∘00
998400
36∘40
998400
36∘20
998400
36∘00
998400
35∘40
998400
Figure 1 Geographic position of Kuriat islands
Temperatures in seven loggerhead turtle nestswere exam-ined using a Hobo data logger Pendant UA TempAlarm(Prosensor Fr) from July to September 2013 on beaches ofSmall and Great Kuriat (when most clutches are in theirthermosensitive stage for sex determination) In order tocover the entire nesting site so that the study could berepresentative of the area the data loggers were distributedto the beaches according to the nesting densities of previousfour seasons 4 in Great Kuriat and 3 in Small Kuriat Withineach nesting beach nests were selected so that the dataloggers were homogeneously spread along the beach lengthFurthermore the locations of studied nests were also chosenwithin the area of mean distance from the wave line based ondata of nests laid at previous seasons In all cases temperaturedata loggers were placed into the centre of the nests beforethe start of the second third of the incubation period eitherduring the egg-laying in the followingmorning or a few daysafter the discovery of the nest In this latter case to avoiddisturbing the nest a small hole was made adjacent to the eggchamber without excavating the nest 3-4 eggs were carefullyremoved in order to place the data logger and then they werereturned to their initial positions with the exact orientationTemperatures at three levels (top middle and bottom) in twonests were also recorded
In order to study the effect of metabolic heating a secondtemperature data logger was buried adjacent to each nest(approximately 1m from the nest at the same depth and thesame distance from the sea) All loggers were programmed torecord a reading every 15 minutes
Nest contents were excavated within a specific periodafter the first hatchling emergence as suggested by Adam etal [35] nest depths were measured and data loggers wereretrieved The total number of eggs (the number of eggs laidinto the nest) and the hatching success were calculated bycounting unhatched eggs dead hatchlings in eggs and deadhatchlings in nests Empty eggshells (gt50 complete) werecharacterized as successful hatching The hatching success() is calculated as follows (empty eggshellstotal number ofeggs) lowast 100 The middle third of the incubation period wascalculated on the basis of the incubation period mentionedabove
Two methods were used to estimate the sex ratio ofhatched loggerhead turtles The first used the mean tem-perature during the middle third of the incubation periodwhile the second used the incubation duration The curvesused for estimation of sex ratio as functions of incubationduration and temperature during the second third of theincubation duration were those of Mrosovsky et al [29]adapted to the field This choice is based on the fact thatturtles from Greece and those of Tunisia are part of the sameMediterranean population and have the same geographicrange It is also based on the fact that pivotal temperaturein marine turtles is a relatively conservative characteristic[13 30] The sex ratio curve ( of females) as a function ofthe mean temperature during the second third of incubationduration was adapted to the field by adding 04∘C [29] whichcorresponds to the difference between ambient temperatureand egg temperature The sex ratio curve ( of females) as
SK6 19-07 21-07 98 959 65GK Great Kuriat SK Small Kuriat lowastDay of excavating the nest
Table 2 Mean temperature in study nests and adjacent sand during different incubation periods IP incubation period The data loggers insand adjacent to nests 6 and 8 in Great Kuriat were lost
Nest In nest In sandTotal IP First third IP Middle third IP Last third IP Total IP First third IP Middle third IP Last third IP
a function of incubation duration [29] was also adapted tothe field by adding 4 days which corresponds to the intervalbetween hatching and the emergence of hatchlings at thesand surface [36]The equations of the two curves used (aftercorrections) calculated by Jribi et al [19] were used and theexact values of sex ratios were derived
These equations are writen as followsThe equation of sex ratio as a function of temperature
derived fromMrosovsky et al [29] is written as follows
119884 =
10006
1 + Exp (+18878 minus 637 lowast 119883) (1)
where 119884 is the sex ratio and119883 is the temperatureThe equation of sex ratio as a function of incubation
duration derived also from Mrosovsky et al [29] is writtenas follows
119884 =
9988
1 + Exp (minus10334 + 182 lowast 119883) (2)
where 119884 is the sex ratio and119883 is the incubation duration
3 Results
During the 2013 nesting season 22 nests were recorded inKuriat islands 13 in Great Kuriat and 9 in Small Kuriat Thisnumber exceeds slightly the average registered since the startof monitoring in 1997 (average = 168 SD = 88 119873 = 17)All these nests were controlled until their emergence andexcavation Table 1 presents the information on the sevenstudied nests
Emergence success was null in two studied nests In nestGK7 the majority of eggs were unhatched (90 of total) andin nest SK5 almost all embryos were dead at a late stage ofembryonic development for unknown reason
The information on temperature recorded in the studiednests and in adjacent sand is presented in Table 2 Twotemperature data loggers buried in the sand were lost theirdata are lacking in the table
The mean temperature of the whole incubation period(each temperature data point recorded was used) for the7 nests ranged from 2746∘C to 2968∘C The maximumtemperature increase during the incubation period was 6∘C(for nest SK6 minimum of 247∘C and maximum of 307∘C)
The mean temperature in nests during the middle thirdof the incubation ranged from 276∘C (Nest GK7) to 293∘C(Nest GK4) The maximum temperature increase duringthis period was 229∘C (nest SK6 minimum of 2816∘C andmaximum of 3046∘C) The minimum temperature increasewas 099∘C (nest SK4 minimum of 2796∘C andmaximum of2895∘C) ignoring the nest GK7 (increase was 06∘C) wherethe majority of eggs were unhatched
The mean temperature during the incubation periodincreased in the middle third of the incubation period com-paredwith the first third and continued to increase during thelast third This is not the case for the adjacent sand (control)where air temperature controls the increase and decreasein soil temperature This evolution of the temperature isobserved in the case of nests in normal conditions (Figure 2in nest GK4 eg) When the conditions are not normal thepatterns become different Figure 3 shows the temperaturesin nest GK7 where the majority of eggs were unhatched and
The Scientific World Journal 5
24
26
28
30
32170713
270713
060813
160813
260813
T∘in nest GK4 in adjacent sand
(∘C)
T∘in nest
T∘in sand
Figure 2 Temperatures in nest GK4 (normal nest) and in adjacentsand Note the difference between inside and outside the nest due tometabolic heating
Table 3 Mean temperature (∘C) in different parts of the nests GK6andGK8 during the incubation period T topMmiddle B bottomand TSP thermosensitive period
Period Mean temperatureNest GK6 Nest GK8
Incubationperiod
T 2919 2864M 2903 2824B 2819 2796
Before TSPT 2887 2925M 2819 2860B 2744 2833
TSPT 292 2845M 2898 2804B 281 2781
After TSPT 2949 2823M 2988 2808B 2903 2776
in adjacent sand and the Figure 4 shows the case of nestSK5 where the majority of embryos died in a late phase ofdevelopment and in adjacent sand
The study of temperature at different levels of a nestindicates as expected that temperatures decreased withincreasing depth (Table 3)This parameter was studied in twonests (GK6 and GK8) In these two nests no difference wasrecorded between temperature in the middle part of the nest
25
26
27
28
29
30
31
32
33
210713
310713
100813
200813
300813
090913
190913
T∘ in nest GK7 and in adjacent sand
T∘ in sand
T∘ in nest
(∘C)
Figure 3 Temperatures in nest GK7 (with a majority of unhatchedeggs) and in adjacent sand Note the nest temperature is lower thanoutside temperature lacking metabolic heating
and the mean temperature of the three levels of the nest (119905-test 119905 = 276 119875 value = 0125 for nest GK6 and 119905 = minus108 119875value = 0375 for nest GK8)
Recording temperature in both the sand and the nestsallowed us to compare the temperatures at the same depth inboth settings During the total incubation duration the dailymean sand temperatures were 033∘C to 099∘C lower thanin loggerhead nests at the same time and depth During themiddle third of the incubation period when sex is thoughtto be determined the mean temperature difference betweennest and sand was 056∘C (119899 = 4 021ndash144∘C) In nests GK7with majority of unhatched eggs the difference was minus053∘C
The estimated sex ratios of hatchlings for all studied nestsfrom equations are shown in Table 4
The sex ratio ranged between 0 (with the two methods)and 10 (with the 119879∘ method) or 40 (with the ID method)
All nests were predicted to produce more males With IDmethods only one nest can produce females (40) With 119879∘method only one nest can produce females (10) with threeothers with very low proportion (1 or 2) Comparison ofthe twomethods indicates that sex ratios are not significantlydifferent (119905 = minus08765 119875 value = 043026) Comparison ofthe two methods for Great Kuriat and Small Kuriat takenseparately also shows that there is no significant difference119875 values of the 119905-test for the two beaches were respectively046 and 05
The analysis of the sex ratios estimated by the twomethods shows that there was no difference between the twobeaches of Great Kuriat and Small Kuriat (Kruskal-Wallis test119867 = 0125 119875 value = 0711 for the 119879∘ method and119867 = 0333119875 value = 0414 for the ID method)
6 The Scientific World Journal
Table 4 Information on studied nests with estimated sex ratio (C)
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
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[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
beaches in order to conserve the ldquopopulationrsquos sexual struc-turerdquo and act in an appropriate manner for the protection ofthese endangered reptiles especially in the context of currentglobal warming [11 12] Indeed in species with TSD the sex-determining pathway is extremely sensitive to temperature[13] The transitional range of temperature within which thecomplement of offspring sex shifts from 100 male to 100female (or vice versa) is generally less than 2∘C and may beless than 1∘C [14] while the mean warming predicted on ascale of 100 years is 2∘C [15]
Investigations of the sex ratio of all three classes ofloggerhead turtles (hatchlings juveniles and adults) havesuggested prioritizing the study of the ecological effects ofanthropogenic climate change on marine turtles [10] Suchstudies have recently begun in the Mediterranean regionbut the results cannot yet be considered conclusive at theregional population scale [9] The loggerhead hatchling sexratios are estimated to be female-biased on most beaches inthe Mediterranean [16ndash20] in contrast with more balancedsex ratios in adult and juvenile [21]
Among the worldrsquos seven marine turtle species threespecies are regularly observed in the Mediterranean theloggerhead turtle Caretta caretta the green turtle Cheloniamydas and the leatherback turtle Dermochelys coriacea
All three marine turtle species mentioned were reportedin Tunisian waters but only the loggerhead turtle is a nestingspecies on some beaches [22ndash24] Nesting activity in Tunisiawas mentioned in the literature but not based on systematicsurveys [25ndash27]The nesting of the loggerhead turtle (Carettacaretta) was first recorded in 1988 on the beach situatedbetween Ras Dimas and Mahdia and on the island GreatKuriat [28] the latter of which is considered as the mostimportant nesting site in the country [23 24] Few nests weresometimes laid in other beaches along the Tunisian coasts butthe nesting is not regularly observed
Since 1997 the beaches of both Great and Small Kuriatislands have been monitored to study nesting density andprotect nests nesting females and hatchlings and to deter-mine reproductive parameters Despite the importance of theKuriat islands in Tunisia their beaches should be consideredas minor Mediterranean nesting sites for the loggerheadturtle
Studies of hatchlings sex-ratio in the Mediterraneanconcerned mainly major nesting sites such as Zakynthos [3]and Kyparissia Bay [29 30] in Greece Alagadi in Cyprus[16] Fethiye [31] Patara beaches [17] in Turkey Sirte in Libya[19] but few studies have been conducted for minor nestingsites such as Sicily in Italy [32] The protection and the studyof these minor nesting sites are informative because theycan give an appreciable contribution to sea turtle biologyboth in number and in genetic diversity [24] Moreoverminor site studies may also reveal novel sex-ratio data fortheMediterranean suggesting amuch less female-biased ratiothan previously believed
Recalling the articles of the SPA protocol and the revisedaction plan on marine turtles in the Mediterranean [33]taking into account the new developments concerning con-servation measures based on scientific groundwork andconsidering the potential effects of global warming on future
population structure and on the dynamics of these endan-gered species [11 12] the present study aimed to providedata on hatchling sex ratio estimation from beaches of Greatand Small Kuriat which are the most important nestinggrounds for loggerhead turtles in Tunisia Since the sex ofmarine turtle hatchlings cannot be assessed from externalmorphology as it needs direct observation of the gonadswhich imply to kill the individuals and since sacrificinghatchlings was not an option for ethical and conservationreasons we used incubation duration of clutches and themean temperatures during themiddle third of the incubationperiod as indirectmethods for predicting the sex ratioswithinthe nests
2 Material and Methods
The Tunisian coast spans approximately 1200 km represent-ing about 25 of the coasts of the Mediterranean (about46000 km) [34] In the north most of coasts are rocky whilein the centre and in the south the coasts are mostly sandywith a very large continental shelf in the Gulf of Gabes
The Kuriat islands are situated in the centre of Tunisia(Figure 1) (35∘ 481015840 0510158401015840 N 11∘ 021015840 0510158401015840 E) and lie 18 km from thecoast ofMonastirThey consist of two small islands the SmallKuriat (Kuria Sgira) which is ca 07 km2 and the Great Kuriat(Kuria Kbira) which is ca 27 km2 in area Small Kuriat has atotal of 1500m of sandy beach situated in the north-easternand east parts of the island whereas the rest of the coastlineis rocky or marshy Almost one-third of the Great Kuriatshoreline is rocky and large deposits of sea grass Posidoniaoceanica and detritus further restrict the accessible nestingsites particularly in the south and the south-western beachesThe principal nesting beach lies on the western and southerncoast and it is almost 3000m in length
The nesting season in Kuriat islands generally starts atthe beginning of June and ends at the middle of AugustDeposition of nests occurred in June and mainly in Julywhereas nesting in August remains rare [24] The fieldworkwas conducted during the summer months of 2013 on thebeaches of bothGreat and Small Kuriat Nesting and hatchingactivity were observed over the beaches as part of the long-term monitoring undertaken by the Tunisian Sea Turtle Pro-gramme (TunSTP) since 1997 following a convention signedevery year between the National Institute of Sea Sciencesand Technologies (INSTM) the Regional Activity Centrefor Specially Protected Areas (RACSPA) and the Agencyof Protection and Management of the Littoral (APAL) Thebeach is surveyed throughout the nesting season on bothislands A teamof three to four persons (researchers studentsand volunteers) is permanently present during the season inorder to record female laying or hatchlings emergence datesEach nest was located bywalking on the beach and the preciseGPS position was recorded in order to locate the nest andidentify its first hatchling emergence date For the purpose ofthis study incubation duration is defined as the period in daysbetween observation of the newly laid nest and the first recordof emergence by either direct observation of hatchlings ortheir crawl tracks emerging from nests
The Scientific World Journal 3
45
40
35
30
35302520151050-5
Gulf of Hammemet
Tunisia
10km
Kuriat islands
10∘00
99840010
∘20
99840010
∘40
99840011
∘00
99840011
∘20
99840011
∘40
99840012
∘00
998400
37∘00
998400
36∘40
998400
36∘20
998400
36∘00
998400
35∘40
998400
Figure 1 Geographic position of Kuriat islands
Temperatures in seven loggerhead turtle nestswere exam-ined using a Hobo data logger Pendant UA TempAlarm(Prosensor Fr) from July to September 2013 on beaches ofSmall and Great Kuriat (when most clutches are in theirthermosensitive stage for sex determination) In order tocover the entire nesting site so that the study could berepresentative of the area the data loggers were distributedto the beaches according to the nesting densities of previousfour seasons 4 in Great Kuriat and 3 in Small Kuriat Withineach nesting beach nests were selected so that the dataloggers were homogeneously spread along the beach lengthFurthermore the locations of studied nests were also chosenwithin the area of mean distance from the wave line based ondata of nests laid at previous seasons In all cases temperaturedata loggers were placed into the centre of the nests beforethe start of the second third of the incubation period eitherduring the egg-laying in the followingmorning or a few daysafter the discovery of the nest In this latter case to avoiddisturbing the nest a small hole was made adjacent to the eggchamber without excavating the nest 3-4 eggs were carefullyremoved in order to place the data logger and then they werereturned to their initial positions with the exact orientationTemperatures at three levels (top middle and bottom) in twonests were also recorded
In order to study the effect of metabolic heating a secondtemperature data logger was buried adjacent to each nest(approximately 1m from the nest at the same depth and thesame distance from the sea) All loggers were programmed torecord a reading every 15 minutes
Nest contents were excavated within a specific periodafter the first hatchling emergence as suggested by Adam etal [35] nest depths were measured and data loggers wereretrieved The total number of eggs (the number of eggs laidinto the nest) and the hatching success were calculated bycounting unhatched eggs dead hatchlings in eggs and deadhatchlings in nests Empty eggshells (gt50 complete) werecharacterized as successful hatching The hatching success() is calculated as follows (empty eggshellstotal number ofeggs) lowast 100 The middle third of the incubation period wascalculated on the basis of the incubation period mentionedabove
Two methods were used to estimate the sex ratio ofhatched loggerhead turtles The first used the mean tem-perature during the middle third of the incubation periodwhile the second used the incubation duration The curvesused for estimation of sex ratio as functions of incubationduration and temperature during the second third of theincubation duration were those of Mrosovsky et al [29]adapted to the field This choice is based on the fact thatturtles from Greece and those of Tunisia are part of the sameMediterranean population and have the same geographicrange It is also based on the fact that pivotal temperaturein marine turtles is a relatively conservative characteristic[13 30] The sex ratio curve ( of females) as a function ofthe mean temperature during the second third of incubationduration was adapted to the field by adding 04∘C [29] whichcorresponds to the difference between ambient temperatureand egg temperature The sex ratio curve ( of females) as
SK6 19-07 21-07 98 959 65GK Great Kuriat SK Small Kuriat lowastDay of excavating the nest
Table 2 Mean temperature in study nests and adjacent sand during different incubation periods IP incubation period The data loggers insand adjacent to nests 6 and 8 in Great Kuriat were lost
Nest In nest In sandTotal IP First third IP Middle third IP Last third IP Total IP First third IP Middle third IP Last third IP
a function of incubation duration [29] was also adapted tothe field by adding 4 days which corresponds to the intervalbetween hatching and the emergence of hatchlings at thesand surface [36]The equations of the two curves used (aftercorrections) calculated by Jribi et al [19] were used and theexact values of sex ratios were derived
These equations are writen as followsThe equation of sex ratio as a function of temperature
derived fromMrosovsky et al [29] is written as follows
119884 =
10006
1 + Exp (+18878 minus 637 lowast 119883) (1)
where 119884 is the sex ratio and119883 is the temperatureThe equation of sex ratio as a function of incubation
duration derived also from Mrosovsky et al [29] is writtenas follows
119884 =
9988
1 + Exp (minus10334 + 182 lowast 119883) (2)
where 119884 is the sex ratio and119883 is the incubation duration
3 Results
During the 2013 nesting season 22 nests were recorded inKuriat islands 13 in Great Kuriat and 9 in Small Kuriat Thisnumber exceeds slightly the average registered since the startof monitoring in 1997 (average = 168 SD = 88 119873 = 17)All these nests were controlled until their emergence andexcavation Table 1 presents the information on the sevenstudied nests
Emergence success was null in two studied nests In nestGK7 the majority of eggs were unhatched (90 of total) andin nest SK5 almost all embryos were dead at a late stage ofembryonic development for unknown reason
The information on temperature recorded in the studiednests and in adjacent sand is presented in Table 2 Twotemperature data loggers buried in the sand were lost theirdata are lacking in the table
The mean temperature of the whole incubation period(each temperature data point recorded was used) for the7 nests ranged from 2746∘C to 2968∘C The maximumtemperature increase during the incubation period was 6∘C(for nest SK6 minimum of 247∘C and maximum of 307∘C)
The mean temperature in nests during the middle thirdof the incubation ranged from 276∘C (Nest GK7) to 293∘C(Nest GK4) The maximum temperature increase duringthis period was 229∘C (nest SK6 minimum of 2816∘C andmaximum of 3046∘C) The minimum temperature increasewas 099∘C (nest SK4 minimum of 2796∘C andmaximum of2895∘C) ignoring the nest GK7 (increase was 06∘C) wherethe majority of eggs were unhatched
The mean temperature during the incubation periodincreased in the middle third of the incubation period com-paredwith the first third and continued to increase during thelast third This is not the case for the adjacent sand (control)where air temperature controls the increase and decreasein soil temperature This evolution of the temperature isobserved in the case of nests in normal conditions (Figure 2in nest GK4 eg) When the conditions are not normal thepatterns become different Figure 3 shows the temperaturesin nest GK7 where the majority of eggs were unhatched and
The Scientific World Journal 5
24
26
28
30
32170713
270713
060813
160813
260813
T∘in nest GK4 in adjacent sand
(∘C)
T∘in nest
T∘in sand
Figure 2 Temperatures in nest GK4 (normal nest) and in adjacentsand Note the difference between inside and outside the nest due tometabolic heating
Table 3 Mean temperature (∘C) in different parts of the nests GK6andGK8 during the incubation period T topMmiddle B bottomand TSP thermosensitive period
Period Mean temperatureNest GK6 Nest GK8
Incubationperiod
T 2919 2864M 2903 2824B 2819 2796
Before TSPT 2887 2925M 2819 2860B 2744 2833
TSPT 292 2845M 2898 2804B 281 2781
After TSPT 2949 2823M 2988 2808B 2903 2776
in adjacent sand and the Figure 4 shows the case of nestSK5 where the majority of embryos died in a late phase ofdevelopment and in adjacent sand
The study of temperature at different levels of a nestindicates as expected that temperatures decreased withincreasing depth (Table 3)This parameter was studied in twonests (GK6 and GK8) In these two nests no difference wasrecorded between temperature in the middle part of the nest
25
26
27
28
29
30
31
32
33
210713
310713
100813
200813
300813
090913
190913
T∘ in nest GK7 and in adjacent sand
T∘ in sand
T∘ in nest
(∘C)
Figure 3 Temperatures in nest GK7 (with a majority of unhatchedeggs) and in adjacent sand Note the nest temperature is lower thanoutside temperature lacking metabolic heating
and the mean temperature of the three levels of the nest (119905-test 119905 = 276 119875 value = 0125 for nest GK6 and 119905 = minus108 119875value = 0375 for nest GK8)
Recording temperature in both the sand and the nestsallowed us to compare the temperatures at the same depth inboth settings During the total incubation duration the dailymean sand temperatures were 033∘C to 099∘C lower thanin loggerhead nests at the same time and depth During themiddle third of the incubation period when sex is thoughtto be determined the mean temperature difference betweennest and sand was 056∘C (119899 = 4 021ndash144∘C) In nests GK7with majority of unhatched eggs the difference was minus053∘C
The estimated sex ratios of hatchlings for all studied nestsfrom equations are shown in Table 4
The sex ratio ranged between 0 (with the two methods)and 10 (with the 119879∘ method) or 40 (with the ID method)
All nests were predicted to produce more males With IDmethods only one nest can produce females (40) With 119879∘method only one nest can produce females (10) with threeothers with very low proportion (1 or 2) Comparison ofthe twomethods indicates that sex ratios are not significantlydifferent (119905 = minus08765 119875 value = 043026) Comparison ofthe two methods for Great Kuriat and Small Kuriat takenseparately also shows that there is no significant difference119875 values of the 119905-test for the two beaches were respectively046 and 05
The analysis of the sex ratios estimated by the twomethods shows that there was no difference between the twobeaches of Great Kuriat and Small Kuriat (Kruskal-Wallis test119867 = 0125 119875 value = 0711 for the 119879∘ method and119867 = 0333119875 value = 0414 for the ID method)
6 The Scientific World Journal
Table 4 Information on studied nests with estimated sex ratio (C)
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
Temperatures in seven loggerhead turtle nestswere exam-ined using a Hobo data logger Pendant UA TempAlarm(Prosensor Fr) from July to September 2013 on beaches ofSmall and Great Kuriat (when most clutches are in theirthermosensitive stage for sex determination) In order tocover the entire nesting site so that the study could berepresentative of the area the data loggers were distributedto the beaches according to the nesting densities of previousfour seasons 4 in Great Kuriat and 3 in Small Kuriat Withineach nesting beach nests were selected so that the dataloggers were homogeneously spread along the beach lengthFurthermore the locations of studied nests were also chosenwithin the area of mean distance from the wave line based ondata of nests laid at previous seasons In all cases temperaturedata loggers were placed into the centre of the nests beforethe start of the second third of the incubation period eitherduring the egg-laying in the followingmorning or a few daysafter the discovery of the nest In this latter case to avoiddisturbing the nest a small hole was made adjacent to the eggchamber without excavating the nest 3-4 eggs were carefullyremoved in order to place the data logger and then they werereturned to their initial positions with the exact orientationTemperatures at three levels (top middle and bottom) in twonests were also recorded
In order to study the effect of metabolic heating a secondtemperature data logger was buried adjacent to each nest(approximately 1m from the nest at the same depth and thesame distance from the sea) All loggers were programmed torecord a reading every 15 minutes
Nest contents were excavated within a specific periodafter the first hatchling emergence as suggested by Adam etal [35] nest depths were measured and data loggers wereretrieved The total number of eggs (the number of eggs laidinto the nest) and the hatching success were calculated bycounting unhatched eggs dead hatchlings in eggs and deadhatchlings in nests Empty eggshells (gt50 complete) werecharacterized as successful hatching The hatching success() is calculated as follows (empty eggshellstotal number ofeggs) lowast 100 The middle third of the incubation period wascalculated on the basis of the incubation period mentionedabove
Two methods were used to estimate the sex ratio ofhatched loggerhead turtles The first used the mean tem-perature during the middle third of the incubation periodwhile the second used the incubation duration The curvesused for estimation of sex ratio as functions of incubationduration and temperature during the second third of theincubation duration were those of Mrosovsky et al [29]adapted to the field This choice is based on the fact thatturtles from Greece and those of Tunisia are part of the sameMediterranean population and have the same geographicrange It is also based on the fact that pivotal temperaturein marine turtles is a relatively conservative characteristic[13 30] The sex ratio curve ( of females) as a function ofthe mean temperature during the second third of incubationduration was adapted to the field by adding 04∘C [29] whichcorresponds to the difference between ambient temperatureand egg temperature The sex ratio curve ( of females) as
SK6 19-07 21-07 98 959 65GK Great Kuriat SK Small Kuriat lowastDay of excavating the nest
Table 2 Mean temperature in study nests and adjacent sand during different incubation periods IP incubation period The data loggers insand adjacent to nests 6 and 8 in Great Kuriat were lost
Nest In nest In sandTotal IP First third IP Middle third IP Last third IP Total IP First third IP Middle third IP Last third IP
a function of incubation duration [29] was also adapted tothe field by adding 4 days which corresponds to the intervalbetween hatching and the emergence of hatchlings at thesand surface [36]The equations of the two curves used (aftercorrections) calculated by Jribi et al [19] were used and theexact values of sex ratios were derived
These equations are writen as followsThe equation of sex ratio as a function of temperature
derived fromMrosovsky et al [29] is written as follows
119884 =
10006
1 + Exp (+18878 minus 637 lowast 119883) (1)
where 119884 is the sex ratio and119883 is the temperatureThe equation of sex ratio as a function of incubation
duration derived also from Mrosovsky et al [29] is writtenas follows
119884 =
9988
1 + Exp (minus10334 + 182 lowast 119883) (2)
where 119884 is the sex ratio and119883 is the incubation duration
3 Results
During the 2013 nesting season 22 nests were recorded inKuriat islands 13 in Great Kuriat and 9 in Small Kuriat Thisnumber exceeds slightly the average registered since the startof monitoring in 1997 (average = 168 SD = 88 119873 = 17)All these nests were controlled until their emergence andexcavation Table 1 presents the information on the sevenstudied nests
Emergence success was null in two studied nests In nestGK7 the majority of eggs were unhatched (90 of total) andin nest SK5 almost all embryos were dead at a late stage ofembryonic development for unknown reason
The information on temperature recorded in the studiednests and in adjacent sand is presented in Table 2 Twotemperature data loggers buried in the sand were lost theirdata are lacking in the table
The mean temperature of the whole incubation period(each temperature data point recorded was used) for the7 nests ranged from 2746∘C to 2968∘C The maximumtemperature increase during the incubation period was 6∘C(for nest SK6 minimum of 247∘C and maximum of 307∘C)
The mean temperature in nests during the middle thirdof the incubation ranged from 276∘C (Nest GK7) to 293∘C(Nest GK4) The maximum temperature increase duringthis period was 229∘C (nest SK6 minimum of 2816∘C andmaximum of 3046∘C) The minimum temperature increasewas 099∘C (nest SK4 minimum of 2796∘C andmaximum of2895∘C) ignoring the nest GK7 (increase was 06∘C) wherethe majority of eggs were unhatched
The mean temperature during the incubation periodincreased in the middle third of the incubation period com-paredwith the first third and continued to increase during thelast third This is not the case for the adjacent sand (control)where air temperature controls the increase and decreasein soil temperature This evolution of the temperature isobserved in the case of nests in normal conditions (Figure 2in nest GK4 eg) When the conditions are not normal thepatterns become different Figure 3 shows the temperaturesin nest GK7 where the majority of eggs were unhatched and
The Scientific World Journal 5
24
26
28
30
32170713
270713
060813
160813
260813
T∘in nest GK4 in adjacent sand
(∘C)
T∘in nest
T∘in sand
Figure 2 Temperatures in nest GK4 (normal nest) and in adjacentsand Note the difference between inside and outside the nest due tometabolic heating
Table 3 Mean temperature (∘C) in different parts of the nests GK6andGK8 during the incubation period T topMmiddle B bottomand TSP thermosensitive period
Period Mean temperatureNest GK6 Nest GK8
Incubationperiod
T 2919 2864M 2903 2824B 2819 2796
Before TSPT 2887 2925M 2819 2860B 2744 2833
TSPT 292 2845M 2898 2804B 281 2781
After TSPT 2949 2823M 2988 2808B 2903 2776
in adjacent sand and the Figure 4 shows the case of nestSK5 where the majority of embryos died in a late phase ofdevelopment and in adjacent sand
The study of temperature at different levels of a nestindicates as expected that temperatures decreased withincreasing depth (Table 3)This parameter was studied in twonests (GK6 and GK8) In these two nests no difference wasrecorded between temperature in the middle part of the nest
25
26
27
28
29
30
31
32
33
210713
310713
100813
200813
300813
090913
190913
T∘ in nest GK7 and in adjacent sand
T∘ in sand
T∘ in nest
(∘C)
Figure 3 Temperatures in nest GK7 (with a majority of unhatchedeggs) and in adjacent sand Note the nest temperature is lower thanoutside temperature lacking metabolic heating
and the mean temperature of the three levels of the nest (119905-test 119905 = 276 119875 value = 0125 for nest GK6 and 119905 = minus108 119875value = 0375 for nest GK8)
Recording temperature in both the sand and the nestsallowed us to compare the temperatures at the same depth inboth settings During the total incubation duration the dailymean sand temperatures were 033∘C to 099∘C lower thanin loggerhead nests at the same time and depth During themiddle third of the incubation period when sex is thoughtto be determined the mean temperature difference betweennest and sand was 056∘C (119899 = 4 021ndash144∘C) In nests GK7with majority of unhatched eggs the difference was minus053∘C
The estimated sex ratios of hatchlings for all studied nestsfrom equations are shown in Table 4
The sex ratio ranged between 0 (with the two methods)and 10 (with the 119879∘ method) or 40 (with the ID method)
All nests were predicted to produce more males With IDmethods only one nest can produce females (40) With 119879∘method only one nest can produce females (10) with threeothers with very low proportion (1 or 2) Comparison ofthe twomethods indicates that sex ratios are not significantlydifferent (119905 = minus08765 119875 value = 043026) Comparison ofthe two methods for Great Kuriat and Small Kuriat takenseparately also shows that there is no significant difference119875 values of the 119905-test for the two beaches were respectively046 and 05
The analysis of the sex ratios estimated by the twomethods shows that there was no difference between the twobeaches of Great Kuriat and Small Kuriat (Kruskal-Wallis test119867 = 0125 119875 value = 0711 for the 119879∘ method and119867 = 0333119875 value = 0414 for the ID method)
6 The Scientific World Journal
Table 4 Information on studied nests with estimated sex ratio (C)
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
SK6 19-07 21-07 98 959 65GK Great Kuriat SK Small Kuriat lowastDay of excavating the nest
Table 2 Mean temperature in study nests and adjacent sand during different incubation periods IP incubation period The data loggers insand adjacent to nests 6 and 8 in Great Kuriat were lost
Nest In nest In sandTotal IP First third IP Middle third IP Last third IP Total IP First third IP Middle third IP Last third IP
a function of incubation duration [29] was also adapted tothe field by adding 4 days which corresponds to the intervalbetween hatching and the emergence of hatchlings at thesand surface [36]The equations of the two curves used (aftercorrections) calculated by Jribi et al [19] were used and theexact values of sex ratios were derived
These equations are writen as followsThe equation of sex ratio as a function of temperature
derived fromMrosovsky et al [29] is written as follows
119884 =
10006
1 + Exp (+18878 minus 637 lowast 119883) (1)
where 119884 is the sex ratio and119883 is the temperatureThe equation of sex ratio as a function of incubation
duration derived also from Mrosovsky et al [29] is writtenas follows
119884 =
9988
1 + Exp (minus10334 + 182 lowast 119883) (2)
where 119884 is the sex ratio and119883 is the incubation duration
3 Results
During the 2013 nesting season 22 nests were recorded inKuriat islands 13 in Great Kuriat and 9 in Small Kuriat Thisnumber exceeds slightly the average registered since the startof monitoring in 1997 (average = 168 SD = 88 119873 = 17)All these nests were controlled until their emergence andexcavation Table 1 presents the information on the sevenstudied nests
Emergence success was null in two studied nests In nestGK7 the majority of eggs were unhatched (90 of total) andin nest SK5 almost all embryos were dead at a late stage ofembryonic development for unknown reason
The information on temperature recorded in the studiednests and in adjacent sand is presented in Table 2 Twotemperature data loggers buried in the sand were lost theirdata are lacking in the table
The mean temperature of the whole incubation period(each temperature data point recorded was used) for the7 nests ranged from 2746∘C to 2968∘C The maximumtemperature increase during the incubation period was 6∘C(for nest SK6 minimum of 247∘C and maximum of 307∘C)
The mean temperature in nests during the middle thirdof the incubation ranged from 276∘C (Nest GK7) to 293∘C(Nest GK4) The maximum temperature increase duringthis period was 229∘C (nest SK6 minimum of 2816∘C andmaximum of 3046∘C) The minimum temperature increasewas 099∘C (nest SK4 minimum of 2796∘C andmaximum of2895∘C) ignoring the nest GK7 (increase was 06∘C) wherethe majority of eggs were unhatched
The mean temperature during the incubation periodincreased in the middle third of the incubation period com-paredwith the first third and continued to increase during thelast third This is not the case for the adjacent sand (control)where air temperature controls the increase and decreasein soil temperature This evolution of the temperature isobserved in the case of nests in normal conditions (Figure 2in nest GK4 eg) When the conditions are not normal thepatterns become different Figure 3 shows the temperaturesin nest GK7 where the majority of eggs were unhatched and
The Scientific World Journal 5
24
26
28
30
32170713
270713
060813
160813
260813
T∘in nest GK4 in adjacent sand
(∘C)
T∘in nest
T∘in sand
Figure 2 Temperatures in nest GK4 (normal nest) and in adjacentsand Note the difference between inside and outside the nest due tometabolic heating
Table 3 Mean temperature (∘C) in different parts of the nests GK6andGK8 during the incubation period T topMmiddle B bottomand TSP thermosensitive period
Period Mean temperatureNest GK6 Nest GK8
Incubationperiod
T 2919 2864M 2903 2824B 2819 2796
Before TSPT 2887 2925M 2819 2860B 2744 2833
TSPT 292 2845M 2898 2804B 281 2781
After TSPT 2949 2823M 2988 2808B 2903 2776
in adjacent sand and the Figure 4 shows the case of nestSK5 where the majority of embryos died in a late phase ofdevelopment and in adjacent sand
The study of temperature at different levels of a nestindicates as expected that temperatures decreased withincreasing depth (Table 3)This parameter was studied in twonests (GK6 and GK8) In these two nests no difference wasrecorded between temperature in the middle part of the nest
25
26
27
28
29
30
31
32
33
210713
310713
100813
200813
300813
090913
190913
T∘ in nest GK7 and in adjacent sand
T∘ in sand
T∘ in nest
(∘C)
Figure 3 Temperatures in nest GK7 (with a majority of unhatchedeggs) and in adjacent sand Note the nest temperature is lower thanoutside temperature lacking metabolic heating
and the mean temperature of the three levels of the nest (119905-test 119905 = 276 119875 value = 0125 for nest GK6 and 119905 = minus108 119875value = 0375 for nest GK8)
Recording temperature in both the sand and the nestsallowed us to compare the temperatures at the same depth inboth settings During the total incubation duration the dailymean sand temperatures were 033∘C to 099∘C lower thanin loggerhead nests at the same time and depth During themiddle third of the incubation period when sex is thoughtto be determined the mean temperature difference betweennest and sand was 056∘C (119899 = 4 021ndash144∘C) In nests GK7with majority of unhatched eggs the difference was minus053∘C
The estimated sex ratios of hatchlings for all studied nestsfrom equations are shown in Table 4
The sex ratio ranged between 0 (with the two methods)and 10 (with the 119879∘ method) or 40 (with the ID method)
All nests were predicted to produce more males With IDmethods only one nest can produce females (40) With 119879∘method only one nest can produce females (10) with threeothers with very low proportion (1 or 2) Comparison ofthe twomethods indicates that sex ratios are not significantlydifferent (119905 = minus08765 119875 value = 043026) Comparison ofthe two methods for Great Kuriat and Small Kuriat takenseparately also shows that there is no significant difference119875 values of the 119905-test for the two beaches were respectively046 and 05
The analysis of the sex ratios estimated by the twomethods shows that there was no difference between the twobeaches of Great Kuriat and Small Kuriat (Kruskal-Wallis test119867 = 0125 119875 value = 0711 for the 119879∘ method and119867 = 0333119875 value = 0414 for the ID method)
6 The Scientific World Journal
Table 4 Information on studied nests with estimated sex ratio (C)
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
Figure 2 Temperatures in nest GK4 (normal nest) and in adjacentsand Note the difference between inside and outside the nest due tometabolic heating
Table 3 Mean temperature (∘C) in different parts of the nests GK6andGK8 during the incubation period T topMmiddle B bottomand TSP thermosensitive period
Period Mean temperatureNest GK6 Nest GK8
Incubationperiod
T 2919 2864M 2903 2824B 2819 2796
Before TSPT 2887 2925M 2819 2860B 2744 2833
TSPT 292 2845M 2898 2804B 281 2781
After TSPT 2949 2823M 2988 2808B 2903 2776
in adjacent sand and the Figure 4 shows the case of nestSK5 where the majority of embryos died in a late phase ofdevelopment and in adjacent sand
The study of temperature at different levels of a nestindicates as expected that temperatures decreased withincreasing depth (Table 3)This parameter was studied in twonests (GK6 and GK8) In these two nests no difference wasrecorded between temperature in the middle part of the nest
25
26
27
28
29
30
31
32
33
210713
310713
100813
200813
300813
090913
190913
T∘ in nest GK7 and in adjacent sand
T∘ in sand
T∘ in nest
(∘C)
Figure 3 Temperatures in nest GK7 (with a majority of unhatchedeggs) and in adjacent sand Note the nest temperature is lower thanoutside temperature lacking metabolic heating
and the mean temperature of the three levels of the nest (119905-test 119905 = 276 119875 value = 0125 for nest GK6 and 119905 = minus108 119875value = 0375 for nest GK8)
Recording temperature in both the sand and the nestsallowed us to compare the temperatures at the same depth inboth settings During the total incubation duration the dailymean sand temperatures were 033∘C to 099∘C lower thanin loggerhead nests at the same time and depth During themiddle third of the incubation period when sex is thoughtto be determined the mean temperature difference betweennest and sand was 056∘C (119899 = 4 021ndash144∘C) In nests GK7with majority of unhatched eggs the difference was minus053∘C
The estimated sex ratios of hatchlings for all studied nestsfrom equations are shown in Table 4
The sex ratio ranged between 0 (with the two methods)and 10 (with the 119879∘ method) or 40 (with the ID method)
All nests were predicted to produce more males With IDmethods only one nest can produce females (40) With 119879∘method only one nest can produce females (10) with threeothers with very low proportion (1 or 2) Comparison ofthe twomethods indicates that sex ratios are not significantlydifferent (119905 = minus08765 119875 value = 043026) Comparison ofthe two methods for Great Kuriat and Small Kuriat takenseparately also shows that there is no significant difference119875 values of the 119905-test for the two beaches were respectively046 and 05
The analysis of the sex ratios estimated by the twomethods shows that there was no difference between the twobeaches of Great Kuriat and Small Kuriat (Kruskal-Wallis test119867 = 0125 119875 value = 0711 for the 119879∘ method and119867 = 0333119875 value = 0414 for the ID method)
6 The Scientific World Journal
Table 4 Information on studied nests with estimated sex ratio (C)
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
Figure 4 Temperatures in nest SK5 (majority of eggs with embryosdied in late phase of development) and in adjacent sand Note thelower difference between inside andoutside of the nest after embryosdied on 04092013
Furthermore the analysis of the results of the sex ratiofor the nests laid in early July (1ndash15 July) and those laid in lateJuly (16ndash31 July) showed no significant differences (Kruskal-Wallis test 119867 = 02813 119875 value = 05784 for the 119879∘ methodand119867 = 075 119875 value = 02207 for the ID method)
4 Discussion
Nest temperature and incubation duration are the twoapproaches used for estimating the sex ratios of hatchlingsborn in the minor nesting site of Kuriat islands Tunisiaduring the 2013 nesting season Although the results arecomparable and close the temperature method was moreaccurate because the incubation duration method was based
on the relationship between incubation duration and the tem-perature during the entire development period Therefore itis less accurate as it is indirect and based not only on themiddle third of the incubation duration when sex is thoughtto be determined The other thirds may confound results incase ofwithin clutch heterogeneous temperature regimes [19]
Temperatures from pilot experiments in two nests weremeasured at different parts (topmiddle and bottom) Resultsallowed us to claim that the mean temperature in the centralpart of the nest is representative of the whole nest sectionsRecording only central parts of the nests therefore yielded thebest estimation of sex ratios [8 37] and allowed us to savemore data loggers to be used at other nests
During our study we had the opportunity to monitorthe temperature in nests at different states (i) nests innormal conditions (Figure 2) (ii) nest with majority ofunhatched eggs (Figure 3) and (iii) nest with majority ofdead embryos at late stage of development (Figure 4) Thesethree figures illustrate well the metabolic heating in thenest Clutch temperatures closely followed the course ofsand temperatures during the first third of incubation Theincreasing discrepancy between nest and sand temperatureafterwards is attributed to metabolic heating In the absenceof live embryos there is no metabolic heating Duringthe middle third of incubation duration this increase isestimated to be 056∘C Knowing that we measured the nesttemperature at the centre of the clutch and that it has beenshown however that temperature in loggerhead clutches isnot evenly distributed [8 37ndash41] and that the amount ofmetabolic heating is higher in the centre than at the sides ofthe clutch [39 40] our results are likely to have overestimatedthe amount of metabolic heating experienced by the averageegg This potential bias is not likely to affect the sex ratio inKuriat islands as this heat increase is negligible [18]
The results of our study indicate that the primary sexratio of hatchlings in 2013 was strongly male-biased inKuriat islands (Tunisia) These results are in agreement withthose of Casale et al [32] in Sicily (a minor nesting sitein Italy) and differ from the general pattern of producingfemale dominated sex ration in loggerhead marine turtle ofthe Mediterranean region and globally [7 8 12 16 17 1930 31 37 38] These results confirm also the importanceof studying minor nesting sites because they can give an
The Scientific World Journal 7
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
appreciable contribution to male hatchlings number (sexratio) and genetic diversity [24] At first glance and takinginto account the small area of minor nesting sites in theMediterranean like Kuriat islands it can be assumed thatthey have no significant effect on the Mediterranean female-biased hatchlings production but knowing that majority ofpublished studies concentrated only on major nesting sitesthat attract more attention for protection effort and smallnumber of studies investigated this phenomenon in smallernesting sites and the fact that both sexes of juvenile andadult in Mediterranean foraging grounds in the open seahave approximately equal proportions 50 50 [21] resultsfrom minor nesting sites can be important and can givesome elements of answer to the difference recorded in sexratio among the different life stages of Caretta caretta in theMediterranean which provoke their study more
Taking into account that only females come to beach tolay and show a certain fidelity to their natal nesting sites andthat major nesting sites are producingmainly females we caninfer thatmajor nesting sites remain usuallymajor andminornesting sites with male-biased sex ratios remaining usuallyminor
It would be then very important to continue the esti-mation of sex ratio in Kuriat islands to see if 2013 nestingseason was exceptional or if the male-biased sex ratio is acharacter of the site It is also very important to extend theestimations of sex ratio in order to cover the minor nestingsites even if scattered over long coastal tracts because theymay contribute to a better understanding of the sex ratiopatterns and may also represent important areas in futurescenarios of climate change [11]
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank Directors and staffs ofthe National Institute of Sea Sciences and Technologies(INSTM) the Agency of Protection and Management ofthe Littoral (APAL) and the Regional Activity Centre forSpecially Protected Areas (RACSPA) for support of theconservation program on Kuriat islands Thanks are also dueto the team of volunteers who presented their best to achievethis conservation program The authors would particularlylike to thank the two anonymous reviewers for correctionsand constructive comments All thanks are also addressedto Abdelmaula Hamza and Nadege Zaghdoudi-Allan for therevision of English
References
[1] R A FisherThe Genetical Theory of Natural Selection Claren-don Press Oxford UK 1930
[2] J M Smith and G R Price ldquoThe logic of animal conflictrdquoNature vol 246 no 5427 pp 15ndash18 1973
[3] J A Zbinden C Davy DMargaritoulis and R Arlettaz ldquoLargespatial variation and female bias in the estimated sex ratio ofloggerhead sea turtle hatchlings of a Mediterranean rookeryrdquoEndangered Species Research vol 3 no 3 pp 305ndash312 2007
[4] NMrosovsky ldquoSex ratios of sea turtlesrdquo Journal of ExperimentalZoology vol 270 pp 16ndash27 1994
[5] C L Yntema and N Mrosovsky ldquoCritical periods and pivotaltemperatures for sexual differentiation in loggerhead sea turtles(Caretta caretta)rdquo Herpetologica vol 36 no 1 pp 33ndash36 1980
[6] T Wibbels J J Bull and D Crews ldquoChronology and morphol-ogy of temperature-dependent sex determinationrdquo Journal ofExperimental Zoology vol 260 no 3 pp 371ndash381 1991
[7] T Wibbels ldquoCritical approaches to sex determination in seaturtlesrdquo in The Biology of Sea Turtles P L Lutz J A Musickand J Wyneken Eds pp 103ndash134 CRC Press Boca Raton FlaUSA 2003
[8] J Hanson T Wibbels and R E Martin ldquoPredicted female biasin sex ratios of hatchling loggerhead sea turtles from a floridanesting beachrdquo Canadian Journal of Zoology vol 76 no 10 pp1850ndash1861 1998
[9] P Casale B Lazar S Pont et al ldquoSex ratios of juvenileloggerhead sea turtlesCaretta caretta in theMediterranean SeardquoMarine Ecology Progress Series vol 324 pp 281ndash285 2006
[10] M Hamann M H Godfrey J A Seminoff et al ldquoGlobalresearch priorities for sea turtles informing management andconservation in the 21st centuryrdquo Endangered Species Researchvol 11 no 3 pp 245ndash269 2010
[11] L A Hawkes A C Broderick M H Godfrey and B J God-ley ldquoClimate change and marine turtlesrdquo Endangered SpeciesResearch vol 7 no 2 pp 137ndash154 2009
[12] M J Witt L A Hawkes M H Godfrey B J Godley and AC Broderick ldquoPredicting the impacts of climate change on aglobally distributed species the case of the loggerhead turtlerdquoJournal of Experimental Biology vol 213 no 6 pp 901ndash911 2010
[13] N Mrosovsky S J Kamel C E Dıez and R P van DamldquoMethods of estimating natural sex ratios of sea turtles fromincubation temperatures and laboratory datardquo EndangeredSpecies Research vol 8 no 3 pp 147ndash155 2009
[14] M A Ewert D R Jackson and C E Nelson ldquoPatterns oftemperature-depentdent sex determination in turtlesrdquo Journalof Experimental Zoology vol 270 pp 3ndash15 1994
[15] GIEC ldquoBilan 2007 des changements climatiques Contributiondes Groupes de travail I II et III au quatrieme Rapportdrsquoevaluation du Groupe drsquoexperts intergouvernemental surlrsquoevolution du climatrdquo in Equipe de redaction principale RK Pachauri and A Reisinger Eds p 103 GIEC GenevaSwitzerland 2007
[16] B J Godley A C Broderick and N Mrosovsky ldquoEstimatinghatchling sex ratios of loggerhead turtles in Cyprus fromincubation durationsrdquo Marine Ecology Progress Series vol 210pp 195ndash201 2001
[17] M Oz A Erdogan Y Kaska et al ldquoNest temperatures andsex-ratio estimates of loggerhead turtles at Patara beach on theSouthwestern coast of Turkeyrdquo Canadian Journal of Zoologyvol 82 no 1 pp 94ndash101 2004
[18] J A Zbinden D Margaritoulis and R Arlettaz ldquoMetabolicheating in Mediterranean loggerhead sea turtle clutchesrdquo Jour-nal of Experimental Marine Biology and Ecology vol 334 no 1pp 151ndash157 2006
[19] I Jribi A Hamza A Saied and A Ouergui ldquoSex ratio esti-mations of loggerhead marine turtle hatchlings by incubation
8 The Scientific World Journal
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
duration and nest temperature at Sirte beaches (Libya)rdquo ScientiaMarina vol 77 no 4 pp 617ndash624 2013
[20] W Fuller B Godley D Hodgson S E Reece M Witt and ABroderick ldquoImportance of spatio-temporal data for predictingthe effects of climate change onmarine turtle sex ratiosrdquoMarineEcology Progress Series vol 488 pp 267ndash274 2013
[21] P Casale D Freggi F Maffucci and S Hochscheid ldquoAdultsex ratios of loggerhead sea turtles (Caretta caretta) in twoMediterranean foraging groundsrdquo Scientia Marina vol 78 no2 2014
[22] I Jribi M N Bradai and A Bouain ldquoQuatre ans de suivide la nidification de la tortue marine Caretta caretta auxılesKuriat (Tunisie)rdquo Rapport de la Commission Internationalepour lrsquoExploration Scientifique de la Mer Mediterranee 2001
[23] I Jribi M N Bradai and A Bouain ldquoMarine Turtles nesting inKuriat islands (Tunisia) in 2000rdquoMarine Turtle Newsletter vol96 pp 4ndash6 2002
[24] I Jribi M N Bradai and A Bouain ldquoLoggerhead turtle nestingactivity in Kuriat Islands (Tunisia) assessment of nine yearsmonitoringrdquoMarine Turtle Newsletter vol 112 pp 12ndash13 2006
[25] L P Knoepffler ldquoUne curieuse anomalie de la carapace chezCaretta caretta Lrdquo Vie et Milieu vol 13 no 2 pp 237ndash331 1962
[26] R Argano ldquoPreliminary report on western Mediterranean seaturtlesrdquo WWF Project 1474 1979
[27] G H Parent ldquoQuelques observations ecologiques sur lrsquoherpetofaune de lrsquoıle de Djerbardquo Naturel Belg vol 62 pp 122ndash150 1981
[28] L Laurent S Nouira A Jeudy de Grissac and M N BradaildquoLes tortuesmarines de Tunisie premieres donneesrdquo Bulletin dela Societe Herpetologique de France vol 53 no 1 pp 1ndash17 1990
[29] N Mrosovsky S Kamel A F Rees and D MargaritoulisldquoPivotal temperature for loggerhead turtles (Caretta caretta)from Kyparissia Bay Greecerdquo Canadian Journal of Zoology vol80 no 12 pp 2118ndash2124 2002
[30] A F Rees and D Margaritoulis ldquoBeach temperatures incuba-tion durations and estimated hatchling sex ratio for loggerheadsea turtle nests in southernKyparissia Bay GreecerdquoTestudo vol6 pp 23ndash36 2004
[31] Y Kaska C Ilgaz A Ozdemir et al ldquoSex ratio estimationsof loggerhead sea turtle hatchlings by histological examinationand nest temperatures at Fethiye beach Turkeyrdquo Naturwis-senschaften vol 93 no 7 pp 338ndash343 2006
[32] P Casale G Palilla A Salemi et al ldquoExceptional sea turtle nestrecords in 2011 suggest an underestimated nesting potential inSicily (Italy)rdquo Acta Herpetologica vol 7 no 1 pp 181ndash188 2012
[33] UNEP MAP RACSPA Action Plan for the Conservation ofMediterranean Marine Turtles RACSPA Tunis Tunisia 2007
[34] S Karaa I Jribi A Bouain M Girondot and M N BradaildquoOn the occurrence of leatherback turtlesDermochelys coriacea(Vandelli 1761) in Tunisian waters (Central mediterranean sea)(Testudines dermochelydae)rdquoHerpetozoa vol 26 no 1 pp 65ndash75 2013
[35] V Adam C Tur A F Rees and J Tomas ldquoEmergence patternof loggerhead turtle (Caretta caretta) hatchlings fromKyparissiaBay GreecerdquoMarine Biology vol 151 no 5 pp 1743ndash1749 2007
[36] MHGodfrey andNMrosovsky ldquoEstimating the time betweenhatching of sea turtles and their emergence from the nestrdquoChelonian Conservation and Biology vol 2 pp 581ndash585 1997
[37] Y Kaska R Downie R Tippett and R W Furness ldquoNaturaltemperature regimes for loggerhead and green turtle nests inthe Eastern Mediterraneanrdquo Canadian Journal of Zoology vol76 no 4 pp 723ndash729 1998
[38] A F Rees D Margaritoulis R Newman et al ldquoEcology ofloggerhead marine turtles Caretta caretta in a neritic foraginghabitat movements sex ratios and growth ratesrdquo MarineBiology vol 160 no 3 pp 519ndash529 2013
[39] M H Godfrey R Barreto and N Mrosovsky ldquoMetabolically-generated heat of developing eggs and its potential effect on sexratio of sea turtle hatchlingsrdquo Journal of Herpetology vol 31 no4 pp 616ndash619 1997
[40] D T Booth and K Astill ldquoTemperature variation within andbetween nests of the green sea turtleCheloniamydas (CheloniaCheloniidae) on Heron Island Great Barrier Reefrdquo AustralianJournal of Zoology vol 49 no 1 pp 71ndash84 2001
[41] J D R Houghton and G C Hays ldquoAsynchronous emergenceby loggerhead turtle (Caretta caretta) hatchlingsrdquo Naturwis-senschaften vol 88 no 3 pp 133ndash136 2001
