Toxicology of Household Detergents to Reef Corals Shai Shafir & I. Halperin & Baruch Rinkevich Received: 10 September 2013 /Accepted: 29 January 2014 # Springer International Publishing Switzerland 2014 Abstract Ecotoxicological impacts (survivorship, growth) of two detergents, the linear alkylbenzene sul- fonates (LAS) and the nonionic surfactants, nonylphenol ethoxylate (NPE), were examined on two branching coral species (Stylophora pistillata and Pocillopora damicornis). Nubbins assays (n =1,890, 24-h exposures, 203-day monitoring) revealed high mortality in 1 and 5 mg/l detergents concentrations (for both species combined, LAS LC 50 =1.99 mg/l; NPE LC 50 =2.16 mg/l). Assays further showed deter- gent as species-specific mortalities (Stylophora LAS LC 50 =1.00 mg/l; NPE=3.03 mg/l; Pocillopora LAS LC 50 =2.21 mg/l; NPE=2.26 mg/l), also influenced by genotype-specific mortalities, phenomena which could downgrade genetic diversity of corals in the field, leav- ing frequently or chronically affected areas with detergent-resistant genotypes. Results revealed that LAS detergents were significantly more detrimental to coral nubbins than NPE detergents, resulting in high mortality and reduced tissue growth on substrates. Sur- prisingly, nubbins exposed to second and third LAS treatments exhibited significant higher survivorship levels than after the first exposure, whereas in all NPE treatments, nubbins’ survivorship did not significantly differ in the repeated exposures as compared to the first set of assays. This outcome, while adding to our knowl- edge for the toxicity of various detergents, highlights the need to reduce repeated sewage spills. Furthermore, it is recommended that reef managers should emphasize dis- parate detergents’ ecotoxicity on corals when establish- ing environmental policies. Keywords Detergents . Coral . Ecotoxicology . Linear alkylbenzene sulfonates . Management . Nonylphenol ethoxylate . Reef 1 Introduction Coral reefs, which are generally considered as being the acme of complexity in the marine environment, are also of prime human interest and at the center of the tourism industry; therefore, their deterioration could undermine global tourist business and, consequently, the liveli- hoods of people in affected regions (Méheux and Parker 2006). This fragile ecosystem is influenced not only by direct global changes (Hoegh-Guldberg et al. 2007; Wild et al. 2011) but also by increasing anthro- pogenic activities (DeGeorges et al. 2010) that include domestic sewage (Mora 2008; Reopanichkul et al. 2010). Concomitant with growing populations along the tropical coasts, increasing amounts of cleaning prod- ucts, such as household detergents and surfactants, are released into the environment (Risk et al. 2009) via sewage spills or partially treated sewage discharges. The worldwide surfactant production in 2006 was 12.5 Water Air Soil Pollut (2014) 225:1890 DOI 10.1007/s11270-014-1890-4 S. Shafir : I. Halperin Oranim Academic College, M.P. Tivon 36006, Israel S. Shafir : B. Rinkevich (*) National Institute of Oceanography, Tel Shikmona, P.O. box 8030, Haifa 31080, Israel e-mail: [email protected]
Transcript
Toxicology of Household Detergents to Reef Corals
Shai Shafir & I. Halperin & Baruch Rinkevich
Received: 10 September 2013 /Accepted: 29 January 2014# Springer International Publishing Switzerland 2014
Abstract Ecotoxicological impacts (survivorship,growth) of two detergents, the linear alkylbenzene sul-fonates (LAS) and the nonionic surfactants,nonylphenol ethoxylate (NPE), were examined on twobranching coral species (Stylophora pistillata andPocillopora damicornis). Nubbins assays (n=1,890,24-h exposures, 203-day monitoring) revealed highmortality in 1 and 5 mg/l detergents concentrations(for both species combined, LAS LC50=1.99 mg/l;NPE LC50=2.16 mg/l). Assays further showed deter-gent as species-specific mortalities (Stylophora LASLC50=1.00 mg/l; NPE=3.03 mg/l; Pocillopora LASLC50=2.21 mg/l; NPE=2.26 mg/l), also influenced bygenotype-specific mortalities, phenomena which coulddowngrade genetic diversity of corals in the field, leav-ing frequently or chronically affected areas withdetergent-resistant genotypes. Results revealed thatLAS detergents were significantly more detrimental tocoral nubbins than NPE detergents, resulting in highmortality and reduced tissue growth on substrates. Sur-prisingly, nubbins exposed to second and third LAStreatments exhibited significant higher survivorshiplevels than after the first exposure, whereas in all NPEtreatments, nubbins’ survivorship did not significantly
differ in the repeated exposures as compared to the firstset of assays. This outcome, while adding to our knowl-edge for the toxicity of various detergents, highlights theneed to reduce repeated sewage spills. Furthermore, it isrecommended that reef managers should emphasize dis-parate detergents’ ecotoxicity on corals when establish-ing environmental policies.
Coral reefs, which are generally considered as being theacme of complexity in the marine environment, are alsoof prime human interest and at the center of the tourismindustry; therefore, their deterioration could undermineglobal tourist business and, consequently, the liveli-hoods of people in affected regions (Méheux andParker 2006). This fragile ecosystem is influenced notonly by direct global changes (Hoegh-Guldberg et al.2007; Wild et al. 2011) but also by increasing anthro-pogenic activities (DeGeorges et al. 2010) that includedomestic sewage (Mora 2008; Reopanichkul et al.2010). Concomitant with growing populations alongthe tropical coasts, increasing amounts of cleaning prod-ucts, such as household detergents and surfactants, arereleased into the environment (Risk et al. 2009) viasewage spills or partially treated sewage discharges.The worldwide surfactant production in 2006 was 12.5
Water Air Soil Pollut (2014) 225:1890DOI 10.1007/s11270-014-1890-4
S. Shafir : I. HalperinOranim Academic College,M.P. Tivon 36006, Israel
S. Shafir :B. Rinkevich (*)National Institute of Oceanography, Tel Shikmona,P.O. box 8030, Haifa 31080, Israele-mail: [email protected]
million tons (Ivanković and Hrenović 2010), a substan-tial increase from the 7.2 million tons in 1993 (Di Corcia1998). The growing coral reef tourism industry is an-other culprit for the increasing discharges of detergentsin sewage. Altogether, coral communities are subjectedto increasing concentrations of detergents, reaching ashigh as 5 mg/l levels just a few hours after massivedischarges (Clara et al. 2007).
Detergents are divided into three major groups: non-ionic, anionic, and cationic, which vary in their degreeof biodegradability and ecotoxicity impacts (Lara-Martín et al. 2008; Staples et al. 2004). Within theacknowledged list of anionic surfactants, the linearalkylbenzene sulfonates (LAS) are widely used deter-gents in various household products, abundant in sew-age, and are the topic of detailed concern studies on theireffects on the environment (e.g., European CouncilRegulation [EC] 1488/94). LAS are biodegrading underaerobic conditions on land, but less so in aquatic envi-ronments and under anaerobic conditions (Bakirel et al.2005). Results (Perales et al. 2007) revealed that thebiodegradation time (T50 value) for LAS in seawater is6.67±0.60 days; about twice as long as in freshwaterand that the No Observed Effect Concentration (NOEC)of LAS in seawater (0.25–15 mg/l) is of an order ofmagnitude higher than in freshwater (0.025–0.21 mg/l;Oya et al. 2008). Another widely used group of deter-gents, emulsifiers, and dispersing agents are the nonion-ic surfactants, nonylphenol ethoxylate (NPE). They arethe most widely used members of the larger alkylphenoland alkylphenol ethoxylate family of nonionic surfac-tants, produced in large volumes, with uses that lead towidespread release into the aquatic environment. Inaddition to their various listed impacts, many NPEs areconsidered as endocrine disruptors (with well-documented effects on marine organisms; e.g., Miles-Richardson et al. 1999). NPE production in USA, Eu-rope, Japan, and China reaches 200,000 t/year (Soareset al. 2008). As NPEs are commonly used in householdlaundry detergents, the EPA and the detergent manufac-turers in the USA have cooperated in its reduction.However, NPEs are still widely used in large quantitiesin industrial laundry detergents and have other uses thatlead to their releases into the environment (EPA 2010).Ecotoxicity of different NPE compounds varies in LC50
between 20 and 1,590 μg/l and NOEC of 0.024 mg/l(Soares et al. 2008).
The resilience of coral reefs to global threats (e.g.,seawater warming, ocean acidification) is influenced by
their health status and by their exposure to local anthro-pogenic threats (Carilli et al. 2009; Knowlton andJackson 2008). Although toxicological effects of deter-gents have been tested on various marine organisms(Bakirel et al. 2005; Soares et al. 2008), no data areavailable on their effects on stony corals, the buildingblocks of coral reefs. Previously, we (Shafir et al. 2007)have tested the toxicity and impacts of six oil dispersantson corals and found that even approved-to-use commer-cial compounds damage corals, even at low concentra-tions. Following the same rationale of testing commonlyused anthropogenic-associated compounds on the coralreefs, the research examines here the basic ecotoxico-logical impacts of two essential detergent components(NPE and LAS) on two abundant Red Sea coral species.This was done by employing the coral nubbins assay(Shafir et al. 2006a).
2 Materials and Methods
Three colonies of each of the two coral branching spe-cies, Stylophora pistillata and Pocillopora damicornis(commonly used as model species in the research), werecollected from the coral nursery in Eilat, Red Sea (Shafiret al. 2006b; known as different genotypes) andtransported immersed in seawater within insulated con-tainers to the National Institute of Oceanography, Haifa,where they were maintained under conditions as perdescription (Shafir et al. 2001). Coral nubbins (averagesurface area 31.1±9.7 mm2, approximately 5–10 polypseach) were prepared according to Shafir et al. (2006a). Atotal of 1,890 coral nubbins were used, 840 fromS. pistillata and 1,050 from P. damicornis. Each treat-ment was conducted in a separate aquarium that wassubjected to the tested detergent (type/concentration),containing 20 or 25 nubbins from each of the threegenotypes from either coral species. Nubbins from eachcoral genotype were glued on glass slides and placedwithin a separate rack, five nubbins per slide, four orfive slides per rack. Stock detergent solutions for theanionic detergent (LAS) and the nonionic detergent(NPE) were prepared with filtered seawater at 10 mg/lconcentration, labeled as stock solutions.
To simulate in situ acute ecotoxicological events, thecoral nubbins were exposed for 24 h in 10-l aquariums(no water circulation during detergent administration) tothe following detergent solutions: 5, 1, 0.75, 0.5, 0.25,and 0.1 mg/l (made from the same stock solutions), and
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detergent-free seawater, as control. The solutions wereprepared gently to avoid lathering. Water parameters,including salinity, pH, and detergent concentrations,were checked using HPLC with UV and fluorescentdetection (Pesakh 2010), before and after the 24-h treat-ment duration. Following 24-h acute exposure to deter-gents, the nubbins were washed thoroughly with freshseawater for 1 min and placed in aquariums with con-tinuously running seawater (20 l/h). Every week, theracks with nubbins were haphazardly shifted within theaquaria to reduce site-developing impacts. Nubbins’death (survivorship was used as the statistical variable)was determined when no coral tissue or intact polypswere observed; therefore, partly damaged nubbins wereconsidered as alive. The growth of horizontal coraltissue on the substrate (Shafir et al. 2006a, 2007) wasmonitored as representing the corals’ growth rates.
Second and third exposures to detergents were ap-plied on first treatment survivors using the same proce-dures and detergent concentrations as in the first deter-gent application. In the LAS experiments, the secondexposure was applied on day 115 and the third on day152. In the NPE experiment, the second treatments wereapplied on day 74 and the third on day 125. Statisticalanalyses were conducted using SPSS 16 statistical pro-gram. We performed an independent sample t test tocompare toxicity of the two detergents on the differentgenotypes and linear regression to calculate LC50
values. Repeated measures ANOVAwere conducted tocompare between the treatments, the different geno-types, and the repeated exposures to the detergents.Tukey HSD analyses were conducted to compare deter-gent toxicity on survivorship and tissue growth. Aver-ages and standard deviation bars were made on fivereplicates/coral genotype for two Stylophora genotypesand three Pocillopora genotypes.
Detergent levels in the Mediterranean seawater andexperimental tanks showed background concentrationsof 2.24–2.82 μg/l LAS. Detergent levels in the Gulf ofEilat seawater (from where colonies were brought to thelaboratory) were measured and recorded LAS concentra-tions of 0.19–19.1 μg/l (Pesakh 2010). For the NPEconcentration, the Mediterranean and Gulf of Eilat sea-water background NPE levels were 0.28–0.88 and 0.86–1.65 μg/l, respectively (Pesakh 2010). To evaluate fur-ther the existence of detergent doses in experimentaltanks, water samples that were taken at the beginningand the end of the experiments revealed no diminution indetergent levels along experimentation (Pesakh 2010).
3 Results and Discussion
The experiments were performed on 1,680 coral nub-bins, 840 were generated from the three S. pistillatagenotypes and 840 from the three P. damicornis geno-types. Nubbins were exposed for 24 h to six concentra-tions (5, 1, 0.75, 0.5, 0.25, and 0.1 mg/l) of either thenonionic surfactant, nonylphenol ethoxylate (NPE), orthe anionic surfactant, linear alkylbenzene sulfonates(LAS). All nubbins that originated from one of theS. pistillata colonies (in all treatments of both deter-gents, including the controls) died at the beginning ofthe experiment and were excluded from analyses.Unexpected death of 26 % of P. damicornis nubbinsin the NPE experiment control group was recordedat day 8, but this experiment was continued sincethe controls of the LAS treatments were not affect-ed. In another case, death of all nubbins in a single0.5 mg/l LAS-treated aquarium (both S. pistillataand P. damicornis) was observed on day 75, follow-ing a mechanical failure a few days earlier. There-fore, only earlier results from this aquarium wereincluded in the analyses.
Results revealed a clear correlation between elevatedLAS and NPE concentrations and increased coral nub-bins’mortality (Fig. 1). Both species exhibited a similarlevel of sensitivity to the detergents. In the LAS exper-iments, control S. pistillata survivorship 2 weeks afterfirst administration was 88 % (average; n=17.5), a levelthat remained constant during the entire period of115 days (before the second detergent administration).Similar results were obtained from S. pistillata nubbinsin 0.1 and 0.25 mg/l LAS concentrations. In LAS con-centrations of 0.75, 1, and 5 mg/l, survivorship wasreduced to 78, 34, and 3 % (averages; n=15.5, 6.5,and 0.5, respectively), respectively, 28 days after admin-istration and to 65, 32 (averages; n=13 and 6, respec-tively), and 0 % after 115 days (Fig. 1). P. damicorniscontrol nubbins showed 100 % (n=25) survivorshipafter 2 weeks and 96 % (average; n=23.7) survivorshipafter 115 days, whereas 24-h LAS administrations of0.75, 1, and 5 mg/l reduced nubbins survivorship to 97,36, and 1 % (averages; n=24.3, 7.7, and 0.3, respective-ly), respectively, on day 28 and to 38, 29, and 0 %(averages; n=9.3, 4.3, and 0, respectively), respectively,on day 115 (Fig. 1). In the lowest LAS concentrations(0.1 and 0.25 mg/l), the nubbins were not affected andshowed 80 and 91 % survivorship (averages; n=19.7and 21.7, respectively), respectively, on day 28, and 76
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Fig. 1 Long-term survivorship of S. pistillata andP. damicornis nubbins, following 24-h exposures to various LAS andNPE concentrations.Dotted vertical lines indicate second and third exposures to detergents. Standard deviations values are not shown to keep curves clear
Fig. 2 Nubbin survivorship onday 28 as plotted againstdetergents concentrations
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and 91 % survivorship (average; n=19.7 and 21.7,respectively), respectively, on day 115.
Most (91 %; n=17) control S. pistillata nubbins inthe NPE experiment survived 2 weeks after exposureand 79 % (n=15) on day 90 pre-onset of the secondtreatment. Survivorship of nubbins exposed to 0.1 and0.25 mg/l were 79 and 31 % (averages; n=16.5 and 6,respectively), respectively, on day 28 and 68 and 27 %(averages; n=12.5 and 5, respectively), respectively, onday 90. Nubbins’ survivorship in NPE administrationsof 0.75, 1, and 5 mg/l were 74, 85, and 29 % (averages;n=14.5, 16.5, and 5.5, respectively), respectively,28 days from initial and 68, 82, and 24 % (averages;n=12.5, 16, and 4.5, respectively), respectively, on day90 (Fig. 1). Survivorship of control P. damicornis nub-bins was 77% (average n=15.8) after 4 weeks and 60%(average; n=13.3) on day 90. Nubbins’ survivorship in0.1 and 0.25mg/l NPE concentrations were 85 and 82%(averages; n=20.3 and 18.7, respectively), respectively,on day 28. On day 90, nubbins survivorship was still
high, 77 and 75 % (averages; n=17.7 and 16.3, respec-tively), respectively. Under concentrations of 0.75, 1,and 5 mg/l, nubbins survivorship was 76, 70, and 5 %(averages; n=16.3, 15, and 1.3, respectively), respec-tively, on day 28 and it dropped to 67, 61, and 5 %(averages n=13.3, 13, and 1.3, respectively), respectively,on day 90 (Fig. 1).
In detergent concentrations of 0.1, 0.25, and 0.75mg/l, nubbins of the two studied coral species showed,28 days from exposure, similar levels of vulnerabilityto both types of detergents, with similar mortality rates(t test p>0.05). In the higher detergents concentrations(1 and 5 mg/l), in which the main acute ecotoxicologicaloutcome developed, significant difference was foundbetween both species responses (28 days, t testp<0.05). Average nubbins’ survivorship on day 28 cor-related linearly to the dosage of exposure (LAS r2=76 %; NPE r2=79 %; Fig. 2).
Results further revealed that corals display moresensitivity to detergent pollution than some other marineorganisms tested. The calculated corals LC50/24-h treat-ment for LAS is 1.99 mg/l (Table 1), two times highersensitivity than the 4.3 mg/l value recorded for pelagicorganisms (Temara et al. 2001). However, the 2.16 mg/lNPE LC50 calculated for both studied coral species(Table 1) is less sensitive than the 1.59 mg/l recordedfor adult invertebrates (Soares et al. 2008). Above re-sults demonstrated, therefore, that exposure to high con-centrations of LAS (5 and 1 mg/l) and NPE (5 mg/l)detergents have caused significant mortality in bothtested common Indo-Pacific coral species within shortperiods of 28 days from exposure. As LAS is the main
Table 1 Calculated LC50 values for each coral species under LASand NPE administrations
Treatment r2 Equation LC50
LAS-Stylophora 0.777 y=−0.1545x+0.7549 1.00
LAS-Pocillopora 0.762 y=−0.1864x+0.9119 2.21
Total LAS 0.763 y=−0.1814x+0.8607 1.99
NPE-Stylophora 0.699 y=−0.0773x+0.7342 3.03
NPE-Pocillopora 0.922 y=−0.1571x+0.8554 2.26
Total NPE 0.793 y=−0.1195x+0.7586 2.16
Table 2 Nubbins (all genotypes/coral species) at onset of second and third LAS and NPE administrations
Detergent Coral species Treatment
0 0.1 0.25 0.75 1 5
LAS
Second administration Stylophora 17.5±2.1 17.5±3.5 18.0±1.4 13.0±7.1 6.0±8.5 0.0
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component in many household detergents, reef man-agers should pay more attention to its toxicity to coralsin environmental evaluations, monitoring schemes, andpolicies.
The second and third detergent administrations wereapplied on survivors of the first administration and onsurvivors of the second detergent administration, respec-tively, where survivors for each group were consideredas the 100 % values for the follow-up detergent admin-istration (Table 2). These exposure assays were per-formed to examine the influence of repeated detergentfluxes (from sewage spills) on corals, by conducting thesame exposure protocol as in the first acute exposureassay. Surprisingly, nubbins exposed to second and third
LAS treatments exhibited significant higher survivor-ship levels than after the first exposure (repeated mea-sures ANOVA F=7.5; p<0.05; Fig. 3a), whereas in allNPE treatments, nubbins’ survivorship did not signifi-cantly differ in the repeated exposures (repeated mea-sures ANOVA F=0.88; p>0.05; Fig. 3b). As detergentsbiodegrade more slowly in seawater than in freshwater(Perales et al. 2007), it is probable that higher chroniclevels of detergents exist in sewage-polluted areas withhigher detrimental impacts on reef corals. However,repeated acute exposures to the same detergent showeddifferent toxicological effects of both detergent types.LAS treatments had similar toxicological affects in eachexposure, but NPE treatments did not. This adds to the
Fig. 3 Average (±SD) nubbinsurvivorship about 1 month afterfirst, second, and third exposuresto LAS detergent dose (a) andNPE detergent dose (b)
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elevated toxicity influence of LAS and emphasizes onthe need to reduce repeated sewage spills.
Results (Fig. 4) also indicated (statistical analysescould not be performed) genotype-specific mortalities.For example, survivorship of P. damicornis genotypenumber 2 (P2) on day 28 was twice as high as those ofgenotypes 1 and 3, while P1 and P3 showed the samesurvivorship. It is interesting to note that in the NPE-treated nubbins, a genotype that survived the first acutedetergent exposure also survived the repeated expo-sures, a fact that should be reflected in the managementactivities as revealing probable epigenetic outcomesand/or genotypes-specific susceptibility. The differencein physiological resistance of nubbins to repeated LASand NPE treatments may suggest buildup resistance bycorals (possibly by HSP expressions; Mayfield et al.2011) against NPE but not against LAS. This can ex-plain the differences in mortality and tissue growth ratesbetween the detergent-treated nubbins. Another pointfor consideration is genotypic impacts on survivorship.Coral reef resilience depends on biodiversity richness,including high intraspecific genetic diversity. Detergentsthat have different ecotoxicological impacts on differentgenotypes may lower this genetic diversity, leavingareas frequently or chronically affected by detergentpollution with detergent-resistant genotypes, thus reduc-ing reef resilience.
The nubbins that had survived the first treatmentstarted to grow new horizontal tissues on the substrates(followed by deposition of calcium carbonate material)
as expected from the typical growth pattern recorded inprevious laboratory studies (Shafir et al. 2006a). Thepercentages of horizontal growth were calculated fromthe surviving nubbins (Fig. 5). At concentrations of0.75, 1, and 5 mg/l, LAS treatments (for both coralspecies) showed a significant lower percentage of sur-vivorship and horizontal growth at day 115 (TukeyHSDp<0.01; Fig. 5a). Most of the nubbins did not survivethe treatment and those that did survived, failed todevelop horizontal tissues (Fig. 5a). At lower doses of0.1 and 0.25 mg/l, there was no significant differencefrom the controls (Tukey HSD p>0.05; Fig. 5a). NPEtreatments revealed no significant differences at day 74,disclosing high survivorship at concentrations 0, 0.1,0.25, and 0.75 mg/l and significant lower survivorshiponly at 5 mg/l concentration (Tukey HSD p<0.01;Fig. 5b). Horizontal growth under NPE treatment showno significant difference among all treatments (TukeyHSD p>0.05; Fig. 5b).
The no observed adverse effect level (NOAEL) ofLAS is 0.25 mg/l and of NPE 0.75 mg/l (Figs. 3, 4 and5). We are aware of the NOAEL values being muchabove ambient concentrations; however, in sanitarysewer overflows in vicinity of reef areas, detergentconcentrations in seawater can reach lethal levels (Oyaet al. 2008), further supporting the aim of this study toelucidate lethal levels and associated sublethal impacts.
The recent focus on the future of coral reefs world-wide in response to global climate change (Carilli et al.2009; Knowlton and Jackson 2008; Pandolfi et al. 2005)
Fig. 4 Genotype-related averagesurvivorship of S. pistillata (S1,S2) andP. damicornis (P1, P2, P3)nubbins. Values represent averageresults for LAS and NPEconcentrations of 0.75, 1, and5 mg/l on day 28 followingdetergents exposures
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has demonstrated the need to immediately and effective-ly address local anthropogenic stressors to coral reefhealth in order to gain time to address the larger scaleproblems of ocean acidification and mass bleachingevents (van Dam et al. 2011; White and Strychar2011). The growing exposure of corals to domesticsewage (Reopanichkul et al. 2010) is one example ofthe connection between local and global level changescaused by growing human populations near coral reefs(Lewis et al. 2009) and increasing tourism activities.Sewage discharges contain detergents and other pollut-ants (Ivanković and Hrenović 2010), adding to the over-all toxicity. The scenario for 24-h acute detergent spill-age that was tested in this study mimicked recurring
accidental sewage spills (Temara et al. 2001). Clearly,the acute nature of detergents influences may lessencoral population sizes and influence genotypic diversi-ties, diminishing corals’ ability to successfully resistother hazards, of local or of global changes (Carpenteret al. 2008). Such slow degradation of stony corals (asrecorded in Eilat, the Red Sea; Rinkevich 2005), thebuilding blocks of coral reefs, may lead to phase shift ofcoral reef communities (Knowlton and Jackson 2008).This work results emphasize, therefore, the extremeimportance of managing local sewage spills and mini-mizing detergent runoffs from urban/industrial areas andare highly valuable in guiding the development of newproducts (from cosmetic products like shampoos to
Fig. 5 Average survivorship andhorizontal tissue growthpercentages for all nubbins(a LAS, b NPE) subjected todifferent detergentconcentrations, 115 and 74 daysfor LAS and NPE, respectively,following detergentadministrations. Letters a, b (forsurvivorship) and c, d (for tissuegrowth) denote the differentsignificant subgroups followingTukey HSD tests
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industrial detergents), and legislation relating to theseproducts, when considering their release into the marineenvironment.
Acknowledgement This study was supported by a fund fromthe Israeli Ministry of Infrastructure.
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