1
Benthic Habitat Mapping of Cardigan Bay, in
relation to the distribution of the Bottlenose Dolphin
(Tursiops truncatus).
A dissertation submitted in part candidature for the Degree of B.Sc., Institute of
Biological Sciences, University of Wales, Aberystwyth.
By Hannah Elizabeth Vallin
May 2011
© Sarah Perry
i
Acknowledgments
I would like to give my thanks to several people who made contributions to this study being
carried out. Many thanks to be given firstly to the people of Cardigan Bay Marine Wild life
centre who made this project possible, for providing the resources and technological
equipment needed to carry out the investigation and for their wealth of knowledge of
Cardigan Bay and its local wildlife. With a big special thanks to Steve Hartley providing and
allowing the survey to be carried out on board the Sulaire boat. Also, to Sarah Perry for her
time and guidance throughout, in particular providing an insight to the OLEX system and GIS
software. To Laura Mears and the many volunteers that contributed to participating in the
sightings surveys during the summer, and for all their advice and support. I would like to
thank my dissertation supervisor Dr. Helen Marshall for providing useful advice, support, and
insightful comments to writing the report, as well as various staff members of Aberystwyth
University who provided educational support. Finally many thanks to my family and friends
who have supported me greatly for the duration. Thankyou.
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Abstract
The distribution and behaviour of many marine organisms such the bottlenose dolphin Tursiops truncates, are
influenced by the benthic habitat features, environmental factors and affinities between species of their
surrounding habitats. Cardigan Bay along the West coast of Wales is a thriving marine environment. Benthic
habitat mapping of the seabed allows assumptions to be made between particular behaviours such as foraging
and feeding in relation to varying bathymetric characteristics on a fine-scale environment. In addition to
studying the bathymetric layout along Cardigan Bay the extent of the daily oscillating tidal changes were also
investigated. The purpose of this was to see if the spring or neap and ebb or flood of a tide had any effect on the
behaviour and activity level of T. truncates. Data was collected over a three month summer period whilst
onboard a research vessel. Cetacean sightings data were collected, recording exact locations and behaviours of
T. truncates. Following dedicated transect routes from New Quay to Ynys-Lochtyn, using specialised
equipment, the boats own echo-sounder readings and Global Positioning System were used to continuously
collect and calculate depth readings to create a 3-D visual image of the sea floor indicating any bathymetric
features. T. truncatus spent the majority of observational time foraging with over 79% of individuals displaying
this behaviour, and were observed most frequently around New Quay and Ynys Lochtyn headlands as well as
within New Quay bay. Benthic mapping of the area gave rise to two particular features of interest just off New
Quay headland, indicating regions of greater depths and steeper gradients, displaying gully features. However,
these features do not indicate any association with increased foraging or feeding behaviour. The ebb and flood
variation of diurnal tides have a strong influence on the occurrence of T. truncatus displaying foraging and
feeding behaviours within Cardigan Bay. However, there is no significant difference between the monthly
spring and neap tidal oscillations, and effects on the foraging and feeding behaviour of T. truncatus. There was
also no significant difference between the tidal cycle and leaping and milling behaviour of T. truncatus.
Throughout the survey period a high abundance of cetaceans within this coastal region were observed, the
findings and bathymetric features supports the need for the continued conservation for T. truncatus within their
home range of Cardigan Bay.
Key words: Bottlenose dolphin (Tursiops truncates), bathymetric features, Cardigan Bay, tidal cycles, foraging,
feeding.
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Table of Contents
Acknowledgments ................................................................................................... i
Abstract..................................................................................................................... ii
Table of contents...................................................................................................... iii
List of appendices..................................................................................................... iv
List of tables............................................................................................................... v
List of figures............................................................................................................. vi
1. Introduction .......................................................................................................... 1
1.1 Technological advancements............................................................................... 2
1.2 Benthic mapping studies in relation to cetacean distribution and behaviour.. 3
1.3 Tidal influences on cetacean distribution ............................................................ 6
2. Study Area................................................................................................................. 7
2.1 Cardigan Bay........................................................................................................... 7
2.2 Special Areas of Conservation.................................................................................7
2.3 Investigated Area...................................................................................................... 9
2.4 Wild life of Cardigan Bay........................................................................................ 10
3. Aims and Objectives.....................................................................................................12
4. Methods..........................................................................................................................13
4.1 Boat based surveys..................................................................................................... 13
4.2 Survey transect lines.................................................................................................. 13
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4.3 Effort data.................................................................................................................. 16
4.4 Sightings data............................................................................................................. 16
4.5 Data analysis................................................................................................................ 21
4.5.1 OLEX data................................................................................................................ 21
4.5.2 Sightings data analysis.............................................................................................. 21
4.5.3 Statistical analysis..................................................................................................... 22
5. Results............................................................................................................................. 23
5.1 Bathymetric maps......................................................................................................... 23
5.2 Visual display of sightings data................................................................................... 31
5.3 Behaviour and tide analysis.......................................................................................... 33
6. Discussion......................................................................................................................... 38
6.2 tidal influences on Tursiops truncatus........................................................................... 42
7. Conclusion.......................................................................................................................... 45
7.1 limitations and further studies....................................................................................... 46
8. References.......................................................................................................................... 48
List of Appendices
Appendix 1: Additional OLEX and Arc map images.
Appendix 2: Raw sightings information provided on CD and all statistical analysis output
from Minitab of behavioural tide analysis.
v
List of tables
Table 1 Area distances of transect survey area....................................................... 14
Table 2 Ethogram of Tursiops truncatus behaviours ............................................. 17-18
vi
List of figures
Fig. 1 Map of Wales sowing Cardigan bay and the Special Areas of Conservation........ 8
Fig. 2 Map of New Quay and Ynys-Lochtyn...................................................................... 10
Fig. 3 Image of the research boat, the Sulaire.................................................................... 13
Fig. 4 OLEX image of the transect survey area of Cardigan Bay.................................... 15
Image A-H Tursiops truncatus displaying a range of behaviours............................... 18-20
Fig. 5 Image to show seabed features off New Quay headland, with particular interest
looking at a deeper gully feature........................................................................................ 23
Fig.6(A) Image to show in close detail the suspected “trench” extending from New Quay
head land.............................................................................................................................. 24
Fig. 6(B) Image to show in close detail the suspected “trench” extending from New
Quay head land and continuing along the coast line until Cwmtydu, with a marker to
show the deepest point at 16.84m ...................................................................................... 25
Fig. 6(C) Image to show the two intersting features found off New Quay headland..... 26
Fig. 7(A&B) Image to show Ynys Lochtyn headland and a close up image showing the
headland feature extending from Ynys Lochtyn.............................................................. 27
Fig. 8 Screen shot from Arc map to show the variation in depressions of the sea bed
along the New Quay coast line, with an elevation key indicating the vertical
depressions............................................................................................................................ 28
Fig. 9 Arc GIS map showing the contour lines across the surveyed coast line................ 29
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Fig.10 Arc GIS map showing cetacean sightings between June – August 2010 within the
survey and surrounding area along the New Quay coast line......................................... 31
Fig. 11 Arc GIS map image to show only the cetaceans displaying feeding or foraging
behaviour during the survey period and their location.................................................. 32
Fig. 12 Pie chat to indicate the common and most frequent behaviours displayed by T.
truncates during the investigation...................................................................................... 33
Fig.13 Bar chart with standard error bars to show the feeding behaviour of T. truncates
during each tidal state..........................................................................................................35
Fig.14 Bar chart with standard error bars to show the foraging behaviour of T.
truncates during each tidal state........................................................................................ 36
Fig.15 Bar chart with standard error bars to indicate the milling behaviour of T.
truncates, only during the ebb and flow of spring tides..................................................... 37
1
1. Introduction
Biological oceanography offers a wide variety of scientific studies, investigating all aspects
of marine biology. The oceans cover over 71% of the world’s surface, yet it is estimated that
only 5% has been well studied, therefore the world’s oceans are a key environment for further
exploration (Levinton 2009), due to the dynamic liquid medium of the oceans this does cause
some limitations to the extent that these environments can be investigated (Redifern et al.,
2006). The growing need for scientifically based evidence of ocean management has resulted
in many mapping programs with various standards and protocols, such as the Mapping
European Seabed Habitats program (MESH). Such programs assess the health of marine
environments and monitor the biological communities which contribute to the essential
ecosystem (MESH 2007). Mapping the characteristics of the seabed provides an essential
insight for oceanographic, geological, geophysical and marine wildlife analysis investigations
(Jakobsson et al., 2008).
Many marine directives such as the Marine and Coastal Access Act 2009 are proposed to
enforce sustainable management and regulation of marine resources. From this act
established government organisations such as the Marine Management Organisation (MMO)
are responsible for “contributions to sustainable development in marine areas and to promote
the UK government’s vision for a clean, safe, healthy, productive and biologically diverse
oceans, and seas” (MMO). (Web reference 1). Today there is a consortium of organisations
and projects including; Department for Environment Food and Rural Affairs (DEFRA)
marine environment section, Centre for Environment, Fisheries and Aquaculture Science
(CEFAS), UK Sea Map, Irish Sea Pilot, the Joint Nature Conservation Committee (JNCC),
Countryside Council for Wales (CCW) and , European Marine Ecosystem Observatory
(EMECO), all of which rely on the essential information provided via seabed mapping to
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incorporate the marine nature and marine environment management, modelling and research
strategies (JNCC 2006).
1.1 Technological advancements
Seabed mapping began in the 1940’s, using side-scan sonar systems to produce low
resolution images, allowing the detection of large structures within the seabed (Brown et al.,
2002). Rapid development during the 1970’s and 1980’s of acoustic electronics and digital
processing increased the resolution and quality of images (Kenny et al., 2003). Today there
are multiple devices used for seabed mapping, the most common being the combined use of
multi-beam echo-sounders, broad beam acoustic systems and sonar devices that generate high
quality pictures of the seabed. The acoustic backscatter produced can also help to categorise
sediment type and any biological communities such as reefs within an area (Anderson et al.,
2008; Kenny et al., 2003), as well as providing a more detailed understanding of the biotope,
and the topography of benthic habitats (Makie 2007; McGonigle et al., 2009). Multi-beam
eco-sounders such as WASSP manufactured by the New Zealand’s Electronic Navigation
Ltd, were purposely built as a fishing system, able to detect the exact position of schools of
fish and objects such as ropes and cables by scanning and profiling the water column and sea
floor using a wide angle sonar at a high resolution, providing 2-D and 3-D images (web
reference 4). Identification of sediment type via benthic mapping can be monitored over time
and assessed for any changes in the benthic environment due to anthropogenic disturbances
and exploitation of marine areas (Blondel 2008; Kostylev et al., 2001). Optical and acoustic
remote sensing methods are useful to reveal the geophysical characteristics of the seafloor,
which is becoming increasingly important for the management and conservation of marine
areas (Diaz et al., 2004; Kenny 2003).
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As marine habitats are not static and may change over time, integrating benthic mapping and
pelagic conditions is an important area for research and management (Anderson et al., 2008;
Jordan et al., 2005), which can be used to provide evidence to support proposals for new
Marine Protected Areas (MPA’s), for example mapping the seabed habitats around the Kent
Group of Islands has provided distinct zone areas for planning process of MPA’s (Jordan et
al., 2005). It has also been used for the evaluation of fishery management areas (Anderson et
al., 2008). Classifying sediment type and biological communities of the sea bed via benthic
mapping helps to characterize fishing environments in relation to habitat features, indicating
areas of high fish biomass. Anderson (et al., (2008) suggested that the importance of mapping
seabed habitats has the potential to act as proxies, predicting the assemblage and distribution
of a species at a regional environment scale. Analysing the depth and slope of a seabed via
benthic habitat mapping is also crucial for the development and location of pipes, cable routes
and off shore wind farms, as well as regularly updating navigational charts (Andrews 2003).
1.2 Benthic mapping studies in relation to cetacean distribution and behaviour
A study by Baumgartner (1997) investigated the distribution of Risso’s dolphin (Grampus
griseus) in relation to the topography and physical environment, particularly with regard to
the water depth and seafloor gradient of the northern Gulf of Mexico. This area has a
particularly high diversity of cetacean species including Tursiops truncates (Davis et al.,
1998). It was found that along steeper slopes of the continental shelf, where oceanic frontal
systems develop, and in areas where the topography varied such as shelf-edge canyons, -
upwelling causes an influx of nutrients stimulating the increase of planktonic biomass
(Canadas et al., 2002; Davis et al., 1998, 2002; Yen et al., 2004). Approximately nineteen
cetacean species were concentrated near circulatory features such as cyclone-anticyclonic,
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warm and cold-core eddies of the northern Gulf of Mexico, increasing primary productivity
in nutrient rich waters (Davis et al., 2002; Johnston et al., 2005). High levels of ocean
productivity have also been studied adjacent to upwelling regions in the California Current
System (Yen et al., 2004). This association attracts the aggregation of prey species including
fish, such as butterfish (Perprilus burti) and other top predators, Atlantic bluefin tuna
(Thunnus thynnus thynnus), seabirds and cetaceans such as pilot whales (Globicephala
melaena). The abundance of species within this area attracted Risso’s dolphins, found to
forage around the upper continental slopes (Baumgartner 1997). Enhanced feeding
opportunities for higher marine predators such as T. truncatus, are also found in specific areas
where there is vertical stratification of the water column as well as nutrient upwelling (Yen et
al., 2004). Distribution of harbour porpoises (Phocoena phocoena) studied in the Bay of
Fundy, again supports the theory of enhanced foraging and feeding with aggregation of prey
in areas relating to oceanographic features (Johnston et al., 2005).
The distribution of many marine organisms including cetaceans is influenced by the benthic
habitat features, environmental factors and affinities between species (Anderson et al., 2009;
Gutierrez., 2000). Dolphins are one of the most well studied cetaceans (Barros et al., 1998;
Weir et al., 2001), however, for the most part, dolphins are extremely mobile and disperse
greatly across their environment. Many studies have investigated the surface behaviour of
dolphins and little is known of their submarine behaviour. Thus model representations of the
seabed allow assumptions to be made between foraging behaviour and bathymetric
characteristics on a fine-scale environment (Anderson et al., 2009). Hastie (et al. (2004)
demonstrated the relationship between habitat features and the distribution of the bottlenose
dolphin (T. truncatus) in the Moray Firth. In conjunction with Wilson (1997) it was
hypothesised that the distribution of dolphins in relation to bathymetry was due to foraging
benefits. Coastal inlets and deep seabed canyons were believed to cause a bottleneck effect
5
for prey and migrating fish, which is where dolphins were observed foraging and feeding
frequently. Foraging seabirds such as short-tailed shearwaters (Puffinus tenuirostris), and
gannet’s (Morus bassanus) are often found at associated cetacean foraging sites where there
is a degree of bathymetric features (Baumgartner et al., 2001; Hunt et al., 1996; Yen et al.,
2004).
Hastie (2004) observed surface foraging behavioural patterns of the bottlenose dolphins
(T.truncates) to see if the distribution was related to the submarine habitat features. It was
discovered that although dolphins do have a relatively large ranging distribution throughout
their habitats (Redifern et al., 2006), pods returned to the same specific areas for prolonged
foraging. These distinct areas had bathymetric characteristics providing a variety of seabed
gradients and water depths that effectively enhanced the opportunity of foraging. T.truncates
to direct their prey towards vertical slopes, forcing them to face a potential barrier thus
making it easier to catch individuals (Hastie 2004). The same relationship with benthic
topography and T. truncatus feeding behaviour is demonstrated across the Mediterranean and
Black Sea. Not only do these areas experience the Atlantic Oceanic frontal system but also
their seabed’s consist of canyons and deep basins, which T. truncatus have demonstrated
using similar feeding methods as mentioned by Hastie (2004) (Natoli et al., 2005). Hooker
(et al.,(1999) investigated a large canyon known as the Gully off the Nova Scotia coast, and
assessed the distribution of cetacean species including T. truncatus. The distribution of
cetaceans was significantly related to the physical features of the bathymetric environment, as
opposed to the abiotic variables of the environment such as water temperature and salinity.
6
1.3 Tidal influences on cetacean distribution
As previously discussed topographical characteristics of the seabed and hydrographic fronts
have an association with cetacean population distributions (Hastie et al., 2003). Distinctive
fronts to investigate are those associated with tidal currents over shallow seabed topography.
The amplitude and extent of the daily oscillating changes in sea level can vary across
different bathymetric regions. An observational study in the inner Moray Firth indicated that
marine predators such as T.truncates were most commonly seen during the flood tide.
Different behaviours and activities were observed during the ebb and flood of each tide;
however it was more predominant during the flood state that foraging, feeding and most
frequently travelling behaviours were observed. During the ebb tide, milling and resting
behaviour were observed more (web reference 3). Within the Bay of Fundy foraging and
abundance of Phocoena phocoena was significantly greater during the flood tidal phase
(Johnston et al., 2005). Research suggests this association is due to the distribution and
movement patterns of prey species, in particular seasonal abundance of the dolphins in
relation to strong tidal currents (Culloch et al., 2008) near to estuarine channel areas,
coinciding with the seasonal migration of adult Atlantic salmon (Salmo salar) (Wilson et al.,
1997; Mendes et al., 2002). Scott et al., (1990) studied T. truncatus in seagrass meadows off
Florida and found that female dolphins occupied productive feeding seagrass areas during the
flood tide.
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2 Study Area
2.1 Cardigan Bay
Cardigan Bay is a thriving environment, supporting a variety of marine wildlife ranging from
marine mammals, fish, marine plants, and reefs to colonies of sea birds (Beddia 2007). The
bay extends over a broad range of the West coast of Wales (Walton 1913), and encompasses
a large proportion of the Irish Sea (Makie 2007). It is one of the largest bays of the British
Isles (Beddia 2007), stretching over sixty miles (CCW 2009) and encompasses an area of
approximately 5500km² (Gregory & Rowden 2001) , from the Llyn Peninsula to St. David’s.
The sediment type across Cardigan Bay is very heterogeneous, ranging from fine sand, gravel
and broken shell to shingle and muddy sands (Evans, 1995). Cardigan Bay experiences semi-
diurnal tides with a uniform tidal range. This is due to its location and the tides of the Irish
Sea entering via St. George’s Channel in the south and flowing northwards where it meets the
tidal currents from the north surrounding the Isle of Man that flow southwards (Gregory &
Rowden, 2001). This causes the tidal currents to travel northward during the flood and
southward during the ebb of the tidal range (Evans, 1995).
2.2 Special Areas of Conservation
It was in 1992 that the European Union (formerly the European Community) produced the
Habitats Directive to establish areas that are in need of conservation management with each
area to be classed as a special area of conservation (SAC). The aim of each SAC is to
“achieve favourable conservation status of a habitat and species features” (Moore 2009).
Collaborating with the Countryside Council for Wales (CCW), under Regulation 33 of the
Habitats Regulations 1994 (CCW 2009), Cardigan Bay was designated as containing two
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SAC’s in 2004 (Beddia 2007). The two areas were selected due to their wealth of marine
habitats such as reefs, sand banks, sea caves, coastal lagoons, estuaries and multiple bays
with an outstanding variety of marine wildlife (CCW 2005).
The Cardigan Bay SAC site extends from Ceibwr Bay, in northern Pembrokeshire, to
Aberarth in Ceredigion. The site covers an area of over 1000km². The Pen Llyna’r Sarnau
SAC covers approximately 230km of coastline, from Penrhyn Nefyn in the north, down to
Afon Clarach on the west coast of Wales (Fig.1).
Fig 1. Map created using Arc Map GIS to show the location of Pen Llyna’r Sarnau SAC and Cardigan Bay
SAC.
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2.3 Investigated area
A particular site of interest along Cardigan Bay for the investigation was the coastline
between New Quay and Ynys Lochtyn (Fig.2). New Quay is a shallow semi-enclosed fishing
bay with a restricted tidal range. Extending from New Quay headland the seabed topography
gradually slopes down, and is composed of coarse and fine sand sediments (Gregory et al.,
2001). New Quay is a popular harbour and especially busy boating area during the main
tourist summer months, with various fishing boats, recreational boats, and tourists’ boats
taking visitors along the coast line to observe the wildlife and coastal cliffs (Pierpoint et
al.,2009) The high cliff face extending from New Quay headland is home to migrating birds
and the largest colony of Atlantic sea birds such as Razorbills (Alca torda), Guillemot (Uria
aalge), Gannet (Morus bassanus) and Cormorants (Phalacrocorax carbo) (Web reference 2).
The rocky headland extending from Ynys Lochtyn is subject to strong turbulence and tidal
rips during each flood and ebb of the tidal currents. The surrounding area of the shore and
seabed is composed of gravel, rocks and coarse sand (Evans 1995).
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Fig 2. Map taken from Google Earth to show location of New Quay and Ynys Lochtyn on the West Coast of
Wales, Cardigan Bay.
2.4 Wildlife of Cardigan Bay
The prime reasoning for Cardigan Bay to have an established SAC status was due to the
population of semi-resident Bottlenose dolphins (T. truncatus) (Moore 2009). These
cetaceans are the most common marine mammal recorded in Cardigan Bay (Beddia 2007).
There is only one other location within the British Isles that has a population of resident
dolphins. The Moray Firth is home to dolphins all year round with seasonal fluctuations of
their abundance (Weir et al., 2001; Wilson et al., 1997).
T. truncatus belonging to the family Delphinidae, suborder Odontoceti and within the order
Cetacea, they are a protected species under the 1992 EU habitats and Species Directive Act
(92/43/EEC) (CCW, Pesanet et al., 2008). T.truncates were found widely distributed
11
offshore and inshore occupying a variety of marine habitats in tropical and temperate waters.
They are a highly sociable species and can be found in large social groups especially
offshore, with hundreds of individuals in one pod, believed to increase protection to the group
and enhance foraging opportunities. They can also be found in pods of just a few individuals
and some may even be solitary, social groups will change in structure and behaviour
continuously. Often pods will cooperate together during group foraging and feeding hunts,
dolphins use echolocation to locate their prey, using a frequency ranging between 40-130
kHz (Beddia 2007; Connor et al., 2002; Weir et al., 2001). T.truncates diet consists of
different species of pelagic fish such as mackerel (Scomber scombrus), pipefish
(Syngnathoides biaculeatus), salmon (Salmonidae), sea bass (Dicentrarchus Labrax) as well
as crustaceans and squid (Epioteuthis lessoniana) (Beddia 2007).
The biodiversity of Cardigan Bay is more varied than just the dolphins alone; Atlantic grey
seals (Halichoerus grypus), harbour porpoise (Phocoena phocoena), river lampreys
(Lampetra fluviatilis), sea lampreys (Petromyzon marinus), pelagic fish such as dab (Limanda
limanda), mackerel (Scomber scombrus) (Gregory et al., 2001) and honeycomb reef worms
(Sabellaria reefs) also inhabit Cardigan Bay (Boyes et al., 2008).
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3. Aims & Objectives
The main aims of this investigation were to determine if there was any relationship in the
distribution of T.truncatus and to successfully map the bathymetric layout of the seabed,
along the coastal region extending from New Quay to Ynys Lochtyn, along the Cardigan Bay
coastline off the west coast of Wales.
Questions to consider for the investigation;
Are there certain points along the coast line that show higher areas of feeding and foraging
behaviour by T.truncatus. If so, do these areas relate to structural points or depth variety of
the seabed topography?
Do dolphins show any foraging or behavioural patterns with tidal cycles or time of day?
Null hypothesis (H0): There is no relationship between the behaviour of T. truncatus and the
tidal cycles.
Alternative hypothesis (H1): There is a clear relationship between the behaviour of
T.truncates and the tidal cycles.
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4. Methods
4.1 Boat based surveys
This particular investigation was carried out whilst on board the Sulaire during June-August
2010 working alongside the Cardigan Bay Marine Wild Life Centre (CBMWC). The Sulaire,
a 33ft turbo diesel charter vessel (Fig 3) was used as the research survey vessel.
4.2 Survey transect lines
Before the investigation began a transect line grid system was developed on the OLEX
system outlining the investigation area from New Quay to Ynys Lochtyn (Fig. 4). The OLEX
combines the boats own echo-sounder readings and Global Positioning System (GPS) to
collect continuously calculated depth readings to display a 3D visual image on screen of the
sea floor. Producing transect lines provided a set linear route which the boat would follow,
during this time the effort data collected was classed as a “transect survey”. There were
Fig 3. Picture of the Sulaire vessel, source by Hannah Vallin.
14
seventy transect lines in total with a distance of twenty-five metres between each one.
However due to the time period in which this investigation was carried out it was decided that
only the odd transect numbers would be followed as this was deemed to provide enough
information to give a detailed image of the seafloor.
Table 1. In comparison with fig.4, area distances out lining the entire survey area.
Site Area Area Distance, Nautical Mile (nm)
Outside transect line of study area from New Quay Ynys Lochtyn.
5.06
Inside transect line of study area from New Quay to Ynys Lochtyn.
4.98
Vertical transect line at Ynys Lochtyn headland.
0.70
Vertical transect line at New Quay headland.
0.27
At the beginning of each boat trip an odd numbered transect line was chosen at random to
follow, which was started once the boat had left the main harbour and was in the study area.
The boat had to stay on a constant line for the entire trip to obtain accurate depth reading
points. Transects lines and depth data collection were only carried out when the sea and
weather states were calm, as a rough sea state would cause the boat to deviate from the route
chosen.
15
16
Fig 4. Screen shot taken directly from the OLEX screen to show the transect lines of the study area.
4.3 Effort Data
On every boat trip at least two trained volunteers were on board to record the effort and
sightings data. Environmental factors “Effort lines” (example in Appendix 1) were recorded
every fifteen minutes, when conditions remained the same or a new effort line was started if
there was a change in any of the following survey conditions; speed, boat course, effort time,
precipitation, sea state, wind direction and/ or wind force. As soon as the boat survey began
effort data was recorded throughout the period of the trip. The use of a hand held GPS
provided most of the information needed to fill out effort lines recording; time, latitude,
longitude of boat location (˚), boat speed (knots), boat course. Additional physical weather
conditions of each survey day were recorded including; precipitation type, visibility (km),
swell height (light 0-1m, moderate 1-2m or high >2m), wind direction, wind force (according
to the Beaufort Scale), cloud cover (amount of sky covered by clouds, measured in eighths),
sea state (0= mirror calm, 1= small ripples, 2= small waves, 3= occasional whitecaps, 4=
frequent whitecaps.) The effort type of each survey was recorded depending if the trip was a
casual watch (CW) (nobody sat observing from the roof of the boat), dedicated search (DS)
(observer on the roof, but not a line transect survey), line transect (LT) (observer on the roof
and following a predefined route through SAC), photo identification work (ID) and it was
noted it there were any other boats in the vicinity.
4.4 Sightings Data
During the survey CBMWC team members observed and scanned the study area for any
cetacean sightings using the naked eye and binoculars. When there was a sighting of T.
truncatus, Phocoena phocoena or Halichoerus grypus, it was recorded on the “sightings data
17
form” (example in appendix 1). Once an animal was sighted the following information was
recorded on the sightings form; time, latitude and longitude from GPS at point of encounter,
angle from boat (either port left (P) or starboard right (S), and the angle obtained from the
protractor 0-180˚), distance in meters of the animal away from the boat, species seen (BND=
bottlenose dolphin, HP = harbour porpoise, GS = Grey Seal), numbers seen (and estimate of
number of adults, juveniles, calves and new born), any additional congregations of birds in
close proximity to sighting ( HG = herring gull, K = kittiwake, GT = gannet, MS = Manx
shearwater, R = razorbill, G = guillemot, MG = mixed gulls, O = other species), number of
birds seen and bird behaviour (T = travelling/flying, R = resting, F = feeding, A= association
with cetacean), and cetacean behaviour/direction of travel. The cetacean behaviours were
recorded as follows; travel (T), fast travel (FT), foraging (FO), feeding-fish seen (FF), leaping
(L), tail slap (TS), rest (R), milling at the surface (M), bow ride (BR), wake ride (WR),
socialising (SO), close contact (CC) loose group (LG), unknown (U), other (O). For
Halichoerus grypus behaviours included; hauled out (H), in water (W), swimming (S), and
other (O). The direction of travel of the T. truncatus were recorded via a compass, VAR =
variable direction. The cetacean behaviours recoded were based on the following ethogram of
behavioural characteristics as dedicated by the CBMWC, with further descriptions discussed
in Muller et al.,(1998) (Table 2).
Table 2. Ethogram describing common behaviours seen and recorded by T.truncatus.
Behaviour Description
Travel Regular surfacing at a fairly constant speed, no associated splashes
Fast travel Rapid swimming, with frequent surfacing creating splashes at a speed >3 knots
Foraging Same behaviour as feeding but no evidence of predator prey contact.
Feeding
Evidence of fish seen either in dolphin’s mouth or being thrown out of the
water, rapid changes of dolphin movement in pursuit of prey and predatory
dives associated with flukes up.
18
Leaping
Forward airborne leap out of the water, progressing forward whilst in the dorsal
position, with a slight concave arch of the body axis.
Tail slap
The fluke is raised about the surface of the water and brought down flat hitting
the surface of the water, maybe done during travel or while the dolphin is
stationary.
Rest
Same as milling however dolphins may lie motionless at the surface for a
prolonged length of time.
Milling
Very slow swimming around the surface waters <3 knots, no geographic
movement in direction of travel.
Bow ride Swimming in close contact to the boat and riding in bow wave
Wake ride
Fast swimming and forward progress associated with repeated leaps occurring
when an individual emerges from the back of a wave, often performed by
multiple individuals simultaneously.
Socialising
Two or more dolphins in close/physical contact. Multiple activities seen
possible mating or aggression with flukes breaking the surface of the water.
Close
contact Individual dolphins in school are less than one body length from other members
Loose
group
Dolphins more irregularly spread over an area with individuals >five body
lengths from each other.
Unknown Behaviour unable to be verified and may be described in additional notes
©Sarah Perry
A
B
19
©Sarah Perry
©Kate Redman
C
D
E
©Sarah Perry
20
©Sarah Perry
©Steve Hartley
F
G
Images A-H Represent common T.truncatus behaviours, pictures sourced by Steve Hartley, Sarah Perry, Kate Redman CBMWC and Hannah Vallin . A-fast travel, B-travel, C-leaping, D-milling, E-feeding, F-tail slap, G-mother and calf foraging.
©Hannah Vallin
21
4.5 Data Analysis
4.5.1 OLEX Data
One of the objectives of this study was to develop bathymetric maps of the seabed off New
Quay coastline. This was done using the OLEX system, collecting the boats echo-sounder
readings and GPS locations throughout the study area over a three month period and
automatically calculating the depth allowed 3D visual images to be produced, showing
interesting features of the sea bed topography. The data readings from the OLEX were
exported as a text file and edited in Excel, ready to be used in Arc map Geographic
Information System (GIS) version 9.3, which allows multiple layers to be built up and
displayed in a two or three dimensional view. The data was sorted into longitude, latitude and
depth (metres), this was then inputted into Arc map to produce a visual image to show each
transect line and exact position that was being investigated within the study area. In Arc map
it was possible to create a map showing the topography contours, and elevation across the
study area from New Quay to Ynys Lochtyn.
4.5.2 Sightings Data
Over the three month investigation 241 sightings of cetaceans were recorded. The latitude
and longitude of each sighting had to be converted from decimal minutes into decimal
degrees. This was done in Excel, then integrated into Arch map, showing the position of the
boat at times of an encounter. This gave the position of the boat, however to work out the
exact position of the cetacean the recorded position of the boat; latitude, longitude, boat
bearing, and distance of encounter from boat (km) were converted using a bearing and
22
distance calculator. By inputting these values an accurate geographic position of each
cetacean was obtained and put into Arc map along with the previous maps (as discussed in
4.5.1), to visually show the distribution of cetaceans . Looking to see if there were certain
points along the coast line that show higher areas of feeding and foraging behaviour by
T.truncatus, and if these areas relate to topographical features of the seabed. All the sightings
that included either feeding or foraging were separated from the main data sets and added as
another layer into Arc map.
4.5.3 Statistical Analysis
To determine whether the behaviour of T. truncatus is influenced by the tide cycles during
spring or neap cycles, statistical analysis was performed using the statistics software package
Minitab 15. The data was sorted so that only sightings of T. truncatus showing foraging and
feeding behaviours were evaluated. Using the timing of the sighting along with the use of a
tide table of New Quay; it was possible to determine for each individual sighting if it was
during the ebb or flood of a spring or neap tide. Statistical analysis of this data included the
test for equal variances to test the data for normality, followed by a non parametric Kruskal
Wallis test and a general linear model representing a parametric 2-way Analysis Of Variance
(ANOVA), this was done to compare the feeding and foraging behaviour separately.
Additionally a non-parametric Mann- Whitney U test was carried out on the milling and
leaping behaviour of T. truncatus.
23
5. Results
5.1 Bathymetric Maps
The following screen shot images were developed on the OLEX system, showing detailed
topography of the sea bed within the investigated area (all other additional maps and images
provided in Appendix 2).
Fig. 5 Image to show seabed features off New Quay headland, with particular interest looking at a deeper gully
feature indicated via the dark blue line.
24
Fig. 6 (A) Image to show in close detail the “gully” extending from New Quay head land.
25
Fig. 6 (B) Image to show in close detail the “gully” extending from New Quay head land and continuing along
the coast line until Cwmtydu, with a marker to show the deepest point at 16.84m .
26
Fig. 6 (C). Image to show the two intersting features found off New Quay headland, located within the red
circles.
27
Fig 7 (A). Image to show Ynys Lochtyn headland, darker blue areas represent deeper sea bed regions.
Fig 7 (B). Close up image showing the headland feature extending from Ynys Lochtyn.
28
The depth contours of the sea bed were incorporated into Arc map GIS to create the
following images to show the elevation of the sea bed and contour lines.
Fig 8. Screen shot from Arc map to show the variation in depth of the sea bed along the New Quay coast line,
with an elevation key indicating the vertical depressions with a minimum of 0.16m, and maximum of 29.34m.
Ynys Lochtyn
New Quay
29
Fig 9. Screen shot from Arc map GIS showing the contour lines across the surveyed coast line.
The bathymetric maps developed on the OLEX (Figs. 5-7) have successfully provided good
visual images of the topography of the seabed, indicating a variety of depths and determining
a range of sedimentary compositions such as fine sands, gravel and rocks (closer detail of this
provided in appendix 2). Particular topographical interests are that seen directly off New
Quay head land, (Fig. 5). The darker blue areas indicate regions of considerable depth on the
sea bed compared to the surrounding area, as outlined in Fig. 6C a smaller feature
approximately 0.23 nm off the headland suddenly drops from 11.04m at the perimeter of the
feature down to 29.34m. (Fig. 6A) shows a clear image of how the seabed gradually slopes
down extending from New Quay headland to a significant gully. Adjacent to this is a linear
Ynys Lochtyn
New Quay
30
gully continuing along the coast line down to Cwmtydu also outlined in Fig .6C, Fig. 6B
suggests this feature to show characteristics of a shallow ocean gully. The progressive decline
of the seabed down to approximately 10.88m is clearly evident. The deepest part of the gully
is 16.84m, and the depth of this remains fairly constant from its origin, 0.39nm off New Quay
headland down to Cwmtydu where it is roughly 0.60nm from the shore coastline.
The alternative headland region of the investigated area at Ynys-lochtyn (Fig. 7 A&B) does
not suggest any particular depression features of the seabed, other than the gradual decline of
the slope extending to deeper waters further off shore, again indicated by darker blue regions.
As suspected the gradient directly surrounding the Ynys-lochtyn headland is greater (Fig.
7B), with depths ranging from approximately 6.12m to greater than 10m, and the sediment is
less varied than New Quay headland mainly being composed of only fine sands.
Additional maps created in Arc map support the varying topography depths and features of
the seabed as seen in the OLEX images. In comparison to (Fig. 8) the deeper depressions
ranging between 16.371- 26.098m correlate with the suspected features around each headland
and the potential gully. Further evidence of the bathymetric layout is also displayed via the
contour lines of the sea bed (Fig. 9), closer lines represent greater gradients of depths, again
correlating to the features as previously described.
31
5.2 Visual display of sightings data.
From the sightings data the following maps were created on Arc map GIS to show the
distribution of cetacean sightings within the survey area.
Fig.10 Image shows all the cetacean sightings represented via the yellow crosses, between June – August 2010
within the survey and surrounding area along the New Quay coast line, image developed in Arc map GIS.
32
Fig.11. Arc map GIS image to show only the cetaceans displaying feeding or foraging behaviour during the
survey period and their location, represented by yellow diamonds.
T. truncatus were abundantly sighted within the survey area (Fig.10), showing high densities
particularly surrounding New Quay headland. Upon investigating whether T. truncatus
feeding and foraging behaviour had any relation to bathymetric depth (Fig. 11), it was clearly
evident that these particular behaviours were concentrated around each headland in shallower
regions, and fairly dispersed throughout the survey region . However upon closer analysis
(images provided in appendix 2) there were fewer foraging and feeding encounters within the
deeper topography regions highlighted in fig.6C.
33
5.3 Behavioural and tide analysis.
During July – August 2010 there were 520 cetacean sightings, of which 487 were T.
truncatus, and the remaining 33 were P.phocoena. (full sightings information and data
analysis output provided in appendix 3.)
Fig. 12. Pie chat to indicate the common and most frequent behaviours displayed by T. truncatus during the
investigation.
34
The results from the statistical analysis for the feeding behaviour alone, demonstrated that it
was not normally distributed and that the data came from populations of different variance,
on the assumption of t he Bartlett’s (P-value of 0.000), when carrying out the test for equal
variances at the 95% Bonferroni confidence interval with feeding and spring/ neap and
feeding with ebb/ flow tide states. Transformation of the data was attempted using the
Logarithm base 10, square root and Natural Logarithm to try and transform the data so that it
was normally distributed. However this was unsuccessful.
The results of a Kruskal- Wallis (KW) test for the feeding behaviour between spring and neap
tides were not significant (H=0.02, DF=1, P-value = 0.896.) The P – value is too high above
the level of significance (>0.05) therefore it is appropriate to accept the H0 that there is no
significant difference between the T. truncatus feeding behaviour during the spring and neap
tidal cycles. The results of a Kruskal- Wallis test for the feeding behaviour between ebb and
flow states of the tide were significant (H=39.28, DF=1, P- value = 0.000).
A parametric general linear (GLM) model test was carried out on the feeding data, at a 1%
(0.01) significance level for the reason that it is a parametric test being used on non-
parametric data. The GLM results for T. truncatus feeding during the ebb and flow tide states
were significantly different (DF= 1, F=46.70, P- value = 0.000). However GLM results of
feeding behaviour during the spring and neap tides were not significantly different (DF= 1,
F=0.04, P- value = 0.834 > 0.01). Analysing all three factors together Feeding vs. spring/
neap and ebb/ flow, the GL indicates there is a significant difference at the 1% significance
level (DF=1, F= 2.73, P- value = 0.100)
35
Fig 13. A bar chart with standard error bars to show the feeding behaviour of T. truncatus during each tidal
state.
The test for equal variances statistical analysis for the foraging behaviour, similarly to the
feeding behaviour confirmed that it was not normally distributed and that the data came from
populations of different variance; on the assumption of t he Bartlett’s test (P-value = 0.000).
Again the data was transformed in the same way as explained for the feeding behaviour but
showed no alteration of the P- value result (0.000).
The results of a Kruskal- Wallis test for T. truncatus foraging during the spring and neap tides
was not significant (H=0.33, DF= 1, P- value = 0.566). However, the results of a Kruskal-
Wallis test on the foraging behaviour during the ebb and flow of each tide cycle was
significantly different (H=0.33, DF= 1, P- value = 0.000).
Results from a general linear model, analysis foraging behaviour during the ebb and flow is
significantly different (DF=1, F=17.31, P- value = 0.000 <0.01). The result for foraging
behaviour during the spring and neap tides from a general linear model were not significant
(DF=1, F=4.77, P- value = 0.030 > 0.01). Analysing all three factors together Foraging vs.
36
spring/ neap and ebb/ flow, the results from a general linear significant model were
significant (DF= 1, F= 12.75, P- value = 0.000 <0.01).
Fig 14. A bar chart with standard error bars to show the foraging behaviour of T. truncatus during each tidal
state.
Foraging and feeding behaviours were the main behaviours taken into account when
analysing T. truncatus behaviour with tidal cycles; however similar statistical analysis was
also carried out on two additional activities; milling and leaping.
An Anderson Darling test for normality was carried out on each behaviour data set. P- values
both less than 0.05 indicated the data does not follow a normal distribution, thus it was
appropriate to carry out the non-parametric Mann- Whitney-U test (MWU) on both the
milling and leaping behaviour. Results from a MWU test on T. truncatus leaping behaviour
during the spring and neap tides were not significant (W= 422.0, P- value = 0.2634), as were
the results for leaping behaviour during the ebb and flow tide states (W= 441.5, P- value =
0.1457). Results of the MWU test for T. truncatus milling behaviour during the ebb and flow
tides was not significantly different (W=28.0, P- value = 0.0509). (Note there was no
37
analysis of milling during the spring and neap tidal states as all observations of milling
behaviour were seen only during the neap tides.)
Fig 15. A bar chart with standard error bars to indicate the milling behaviour of T. truncatus, only during the
ebb and flow of spring tides.
38
6. Discussion
During this investigation, within the transect survey area T. truncatus spent the majority of
observational time foraging with over 79% of individuals displaying this behaviour (Fig 12),
foraging was most frequently seen around New Quay and Ynys Lochtyn headlands and with
in New Quay bay (Fig 10). T. truncatus displaying foraging behaviour around and within
bays is a common characteristic evident in other studies (Barros et al., 1998;Bearzi 2005;
Chilvers et al., 2001; Fragaszy et al., 2003.) It has been suggested that shallower bay regions
provide safer locations to forage especially for mothers with calves, specifically during
periods of nursing and calves learning how to forage during early spring and the summer
months (Fernandez 1998; Fragaszy et al., 2003). Clear relationships show that foraging and
feeding behaviours by T. truncatus are primarily abundant over particular submarine areas,
with varying topographic features such as steep gradients of the seabed and submarine
canyons (Bearzi 2005; Hastie et al., 2004; Ingram et al., 2002). However this was not seen
during this investigation. The varying gradient of the sea bed gave rise to two particular
features of interest, just off the New Quay headland, indicating regions of greater depths and
steeper gradients. In contrast to previous studies, few foraging and feeding occurrences were
observed directly over these submarine features, yet were abundant within the surrounding
regions and gentle gradients of the bay (Fig 11).
It is known that the distribution and abundance of T. truncatus can be influenced by the
relationship with prey, related to bathymetric characteristics (Hastie et al., 2004). Without
further investigation it is inconclusive from this study that T. truncatus were highly abundant
around the headlands due to the bathymetric layout or aggregation of prey species. A factor to
take into consideration along with the bathymetric topography would be additional
environmental conditions such as, sea surface temperature, salinity and benthic composition
39
and possible distribution mapping of common prey species of T. truncatus, to see further
influences on the distribution and abundance of T. truncatus. As demonstrated by Selzer (et
al., 1998), two different cetacean species, the white-sided dolphin (Lagenorhynchus acutus),
and the common dolphin (Delphinus delphis) were commonly found along deeper nutrient
upwelling regions of continental shelves, this was the primary influencing factor on their
distribution. Both species also indicated secondary influences of their distribution in relation
to sea surface temperatures and salinity levels. From the use of an echo sounder on board the
survey boat it was possible to determine the benthic composition via the OLEX system. New
Quay headland had the greatest variation of sediment including gravel, fine sand, rock and
shells (sediment map available in appendix 2). This correlates with findings from Evans
(1995), who stated this coastal region having a heterogeneous sediment composition.
However the relationship between sediment composition and the distribution and behaviour
of T. truncates requires further investigation to reflect the variation of benthic and pelagic
organisms found associated with each sediment type, further affecting occurrence of prey
species. Cetacean species such as P.phocoena have been found to be more abundant over fine
sandy regions as opposed to rock and gravel sediments, thought to be due to the abundance of
preferred prey species (Bailey et al., 2006, 2009). Additional cetacean species such as the
Minke whale (Balaenoptera acutorostrata acutorostrata) also displayed a preference of their
distribution to benthic areas with sandy gravel sediments, due to the association with sandeels
(Ammodytes marinus) being more abundant buried in soft sediments (Tetley, 2004). This
could be a possible theory to the high occurrence of T. truncatus around the New Quay
headland within the fine sandy benthic regions and possible association with underlying prey
species, although further investigation is needed to determine this.
In addition to foraging, travelling predominately made up the behaviour of T. truncatus, with
over 35% of time spent moving within the Cardigan Bay home range. Bearzi (2005) found
40
that a significant amount of time was spent by T. truncatus foraging, and travelling at slower
speeds within Santa Monica Bay, with occasional surface feeding. It was suggested this was
due to a plentiful prey supply throughout the year. Due to the high abundance of T. truncatus
particularly off New Quay head land this may indicate a favoured region for frequent
prolonged foraging of prey species (Pesante et al., 2008). Also suggested by Defran (et al.,
1999) T. truncatus indicate favoured passages and regions within their home range where
extensive hunting of prey is commonly observed. In a report by the CCW (2008) T.
truncatus in the Cardigan bay SAC were found to have preferred feeding and foraging areas
of New Quay bay within 5km of the coast line, and were not randomly distributed along the
coast, which can relate to the findings of this investigation, although T. truncates were
concentrated around the headlands, they were also commonly sighted across the entire survey
area within close distance to the coast line. Similar results were also found in a study of T.
truncatus within the same region of Cardigan Bay, finding predominately the most common
behaviour was travelling followed by foraging and feeding in shallower waters (Beddia
2007). Although T. truncatus have a large home range moving between a range of depths
and distances from the coast, in general T. truncatus indicate a preference for shallower
waters between 5-15m (Pesante et al., 2008). This could be an explanation as to why
abundant sightings have been seen close to New Quay headland. However one issue to take
into consideration is that within New Quay harbour was the starting and ending location of
each boat based survey; therefore this may have biased the results in that the boat was more
frequently based around the surrounding area.
The location of New Quay’s fishing factory is positioned to the west of the harbour and
deposits the shells from processing whelks and crabs into the sea, licensed by the Marine and
Fisheries Agency. In 2007 it was recorded that within the surrounding area of these deposits
there was an increase in the accumulation of organic matter on the seabed, affecting the levels
41
of productivity and possibly the turbidity of the water column (Evans 2008). As it is within
the area where foraging and feeding sightings were greatly observed this may suggest that
areas of excess organic matter is increasing the abundance of lower prey species leading to
greater fish abundance for T. truncatus to forage on (Pesante et al., 2008).
Multiple reports (Arcangeli et al., 2009; Constantine et al., 2004; Lusseau 2004; Weir et al.,
2001) suggest that the interaction of tourist boats with T. truncatus can deter them and affect
their behaviour. Arcangeli (et al., (2009) reported that tourist boats not only influenced the
type of behaviour but also the duration of resting and feeding behaviours. Overall increased
interactions of boats lead to a significant decrease of the duration spent by individuals resting
and feeding, however, travelling increased and behavioural changes were more frequent. Boat
encounters were found to further influence the population structure of T. truncatus, causing
groups of fewer individuals to spread out further apart in areas of high boat activity. Within
the transect survey area of this investigation, it is also the dedicated route for multiple tourist
boats following the same courses; never the less sightings were still frequent and abundant
throughout the area. This suggests that resident populations of T. truncatus indicate a level of
tolerance to boat traffic (Bristow et al., 2001), other studies indicate that T. truncatus have
been known to associate with boats displaying bow riding and leaping socialising behaviours
(Berrow et al.,1996; Wursig et al., 1979). Arcangeli (et al., 2009) recorded that on close
contact to boats 20% of T. truncatus during the study were attracted to the boats, 28% were
deterred and the remainder remained neutral. During this investigation there were several
occasions of close encounters with the boat, yet social displays such as bow riding were less
frequently displayed (7%). Other common behaviours excluding travelling and foraging,
included leaping (14%), fast travelling in various directions (5%) and feeding (5%).
42
6.2 Tidal influences on T. truncatus
The monthly oscillations of the spring and neap tides and the diurnal changes of ebb and flow
tides subjects marine animals to regular changes of their environment. Crustacean and pelagic
fish species commonly display horizontal and vertical tidal migrations in shallow marine
areas (Gibson, 2003). With particular reference to foraging and feeding behaviours, tidal
variation was shown to have a strong influence on the occurrence of T. truncatus displaying
these behaviours (Acevedo, 1991; Berrow et al., 1996; Gibson, 2003; Harzen, 1998; Mc
Bride et al., 1948; Norris et al., 1961; Wursig et al., 1979). During this investigation the
monthly spring and neap state of a tide showed no significant effect on the feeding and
foraging behaviour of T. truncatus. However, statistically both behaviours appeared to be
strongly influenced by the ebb and flood state of each diurnal tide. The statistical results for
feeding during the neap and ebb tides, concludes that there is no significant difference
between each diurnal tide state. It is clear to see that feeding behaviour is greater during the
flood flow of the diurnal tides, with a greater average number of cetaceans being sighted with
prey. The foraging behaviour of T. truncatus, was not significantly different comparing
spring and neap tide states, Fig .14 indicates that foraging behaviour overall was more
frequent during the ebb flow of the diurnal tides. In comparison to a study by Wursig (et al.,
(1979) particular behaviours such as feeding and foraging were also shown to be influenced
by the tidal states. Wursig found T. truncatus milling and foraging in near shore waters for
several hours and often moved parallel to the coast line in relatively constant depths of water.
Characteristics of milling behaviour is very slow swimming around the surface waters (<3
knots), with varied geographic direction of movement (Muller et al., 1998). During the flood
tide T. truncatus swam into the progressively deeper waters, associated with the movement of
schooling fish. Wursig suspected that flood feeding occurrences were due to the tidal currents
and rising waters, causing an abundance of fish from deeper waters in near shore areas as a
43
potential food source for T. truncatus. This theory could also be the reason as to why feeding
by T. truncatus was more frequent during the flood for this investigation.
The foraging behaviour of T. truncatus during this investigation was more frequent during the
ebb tides, this has also been shown in previous studies (Berrow et al., 1996; Harzen 1998).
Abundance of T. truncatus varies throughout the day, although there are clear correlations to
show the occurrence of T. truncatus is more frequent during mid-ebb tide states, during
which T. truncatus did engage more foraging and additional social behaviours including
milling and socialising (Berrow et al., 1996) . Berrow (et al., (1996) investigated T.
truncatus within the Shannon estuary and concluded that foraging was most frequent during
the ebb tides in narrow regions of the estuary and feeding behaviour commenced during
stronger currents when the tides were coming in.
The associated behaviour of leaping and other aerial displays of activity such as tail slapping
often increase in the level of activity during late afternoon periods, however, there is an
uncertainty to the precise reasoning behind T. truncatus displaying this behaviour (Harzen et
al., 1998). It has been suggested that T. truncatus use leaping as a possible way of
communication when pods are largely separated (Wursig et al., 1979), and tail slapping is an
behaviour associated with the aggression of cetaceans (Shane 1995), or displayed by leaders
of a pod (Wursig et al., 1979). As yet there has been no evidence that this level of activity is
influenced by tidal cycles, as found in this investigation there was no significance between
either the spring, neap, ebb or flow of the tidal cycles.
Particular studies on T. truncatus found that they use sheltered bays during the day as areas
for resting and milling, and ventured out into deeper waters during the night to forage and
feed (Harzen 1998; Norris et al., 1980). The high abundance of T. truncatus within New
Quay bay indicating a favoured region for prolonged foraging was also a common site for
44
resting and milling. On analysis of the milling behaviour (Fig.15) indicates that there is a
tendency for a greater number of cetaceans to display milling behaviour during the flow of a
tide when feeding was more commonly seen. However, the results contradict this and only
just accept the null hypothesis, in that there is no relationship between the milling behaviour
of T. truncatus and the tidal cycles, indicated by the MWU results. Wursig (et al.,(1979),
associated milling behaviour with feeing on solitary prey species as well as benthic organisms
in near shore regions, yet further analysis determining benthic species and prey abundance
will be needed to support this theory.
45
7. Conclusion
This investigation has successfully identified the bathymetric layout of the seabed ranging
from New Quay to Ynys Lochtyn across Cardigan Bay, using GIS to indicate a gradual
sloping topography with two particular sites of deeper gradient variation and substrate
composition. The original questions considered at the beginning of this investigation have
concluded that there are potential areas along the Cardigan coastline which indicate higher
areas of feeding and foraging behaviour by T. truncates, indicated via mapping of cetacean
sightings between New Quay and Ynys-Lochtyn. However it is not possible to conclude the
specific association with benthic features and this behavioural distribution. On determining
the effects of tidal state on particular behaviours, it is possible to state that the most frequent
ebb and flow tidal changes have the greatest affect on foraging and feeding behaviours in
particular. It was possible to accept the null hypothesis in relation to the spring and neap tidal
cycles; however, on relating behavioural occurrences during the ebb and flow tides the null
hypothesis was rejected. The high abundance of cetaceans sighted within this coastal region
during the duration of this investigation, supports the need for the continued conservation
measurements of Cardigan Bay (CCW 2009), for the protection of the cetacean species and
their habitat.
46
7.1 limitations and further studies
It is important to note that this investigation was based on only the diurnal observations of T.
truncates during three months of summer between 9am -7pm, therefore cannot take account
of seasonal or nocturnal variations of behaviour. Other limitations of this investigation are
that over the three month boat surveys different volunteers were used to collect the effort and
sightings data, although all volunteers were given the same training before hand, variations of
individuals surveying techniques may account for inaccurate sightings data. The weather was
a continuous influence as the boat was unable to go out some days due to a rough sea state.
Therefore the amount of time spent observing cetaceans and mapping of the sea bed was not
equally spread across the time period. Timings of surveying periods was not even across the
whole transect area, as previously explained the boat spent a greater amount of time in and
around New Quay harbour, and duration of stopping the boat during cetacean encounters
varied greatly. An error to account for with the statistical analysis of tidal states and
behaviours is that unequal amounts of spring and neap tides were reviewed; there were more
neap occurrences during the survey. Although this study mapped the bathymetric features
over the study site, further investigation is needed to determine the exact association with T.
truncates.
Further studies to carry out from this investigation include; incorporating photo identification
of cetaceans to build up an accurate population structure of individuals with in Cardigan Bay.
Assessing boat interactions with cetaceans in the same region to see the effects on
distribution and behaviour, either by direct associations with the boats or the noise pollution
produced by them. The use of further GIS and synoptic satellite mapping to determine
possible oceanic frontal features that can influence a number of environmental and physical
aspects in relation to cetacean distribution. To help determine the influence of bathymetric
features it would be important to assess the benthic species found across the survey area.
47
Using a drop down camera, and grab sampling to find out exactly what species are present
across a range of varying gradients and benthic substrates can build up knowledge of organic
matter and potential prey species available to cetaceans within Cardigan Bay. Further
investigations for prolonged term monitoring, and research will help to understand the
environmental aspects that influence cetacean behaviour and distribution within their home
range of Cardigan Bay, and support the conservation of such a species across this
environmental region.
48
8. References
Web reference 1: http://www.marinemanagement.org.uk/protecting/conservation/index.htm
(Accessed October 2010.)
Web reference 2: http://www.cbmwc.org/about/what_lives_here.asp (Accessed October
2010)
Web reference 3: http://www.crru.org.uk/cust_images/pdfs/mitcheson_etal_ECS2008.pdf
(Accessed February 2011)
Web reference 4: http://www.olex.no/nyheter_e.html (Accessed October 2010)
Acevedo.A. (1991) Behaviour and movements of bottlenose dolphins (Tursiops truncatus) in
the entrance to Ensenada De La Paz, Mexico. Aquatic Mammals. 17.3, 137-147
Acevedo.A, Wursig.B. (1991). Preliminary observations on bottlenose dolphins (Tursiops
truncatus) at Isla del Coco, Costa Rica. Aquatic Mammals. 17.3, 148-151.
Anderson.J.T, Van-Holliday.D, Kloser.R, Reid.D.G, Simard.Y. (2008). Acoustic seabed
classification: current practice and future directions. Journal of Marine Science. 65, 1004-
1011.
Anderson.J.T, Syms.C, Roberts.D.A, Howard.D.F. (2009). Multi scale fish habitat
associations and the use of habitat surrogates to predict the organisation and abundance of
deep water fish assemblages. Journal of Experimental Marine Biology and Ecology. 379, 34-
42.
Andrews.B. (2003). Techniques for spatial analysis and visualization of benthic mapping
data. Report for National Oceanic and Atmospheric administration Coastal services
centre.623.
Arcangel.A, Crosti.R. (2009). The short term impact of dolphin watching on the behaviour of
bottlenose dolphins (Tursiops truncatus) in western Australia. Journal of Marine Animals
and Their Ecology. 2,
Bailey.H, Thompson.P. (2006). Quantitative analysis of bottlenose dolphin movement
patterns and their relationship with foraging. Journal of Animal Ecology. 75, 456-465.
49
Bailey.H, Thompson.P.M. (2009). Using marine mamal habitat modelling to identify priority
conservation zones within a marine protected area. Marine Ecology Progress Series. 378,
279-287.
Barros.N.B, Wells.R.S. (1998). Prey and feeding patterns of resident bottlenose dolphins
(Tursiops truncatus) in Sarasota bay, Florida. Journal of Mammalogy. 79, 1045-1059.
Baumgartner.M.F. (1997). The distribution of Risso’s dolphin (Grampus griseus) with
respect to the physiography of the northern Gulf of Mexico. Marine Mammal Science. 13,
614-638.
Bearzi.M. (2005). Aspects of the ecology and behaviour of bottlenose dolphins (Tursiops
truncatus) in Santa Monica Bay, California. Journal of Cetacean research and management.
7, 75-83.
Beddia.L. (2007). Diurnal behaviour of bottlenose dolphins (Tursiops truncatus) in the
Cardigan Bay, west Wales. Dissertation, University of Wales, Bangor.
Berrow.S.D, Holmes.B, Kiely.O.R. (1996). Distribtuion and abundance of bottlenose
dolphins (Tursiops truncatus) (Montagu) in the Shannon Estuary. Biology and Environment.
96B, 1-9.
Blondel.P.(2008). A review of acoustic techniques for habitat mapping. Ph.D thesis
Department of Physics, University of Bath.
Boe.R, Rise.L, Ottsesn,G. (1998). Elongate depressions on the southern slope of the
Norwegian trench (Skagerrak): morphology and evolution. Marine Geology. 146, 191-203.
Boyes.S, Mazik.K, Burdon.D. (2008). Intertidal monitoring of Sabellaria alveolata in
Cardigan BaySAC. CCW Marine monitoring report. 43, 1-35.
Boyes.S, Hemingway.K,Mazik.K. (2009). Intertidal monitoring of a sand-scoured
rockpools in the Cardigan Bay SAC. CCW Marine Monitoring Report .55, 1-27.
Bristow.T, Rees.E.I.S. (2001). Site fidelity and behaviour of bottlenose dolphins (Tursiops
truncatus) in Cardigan bay, Wales. Aquatic Mammals. 27.4, 1-10.
50
Brown.C.J, Cooper.K.M, Meadows.W.J, Limpenny.D.S, Rees.H.L. (2002). Small scale
mapping of sea-bed assemblages in the eastern English Channel using sidescan sonar and
remote sampling techniques. Estuarine, Coastal and Shelf Science. 54, 263-278.
Canadas.A, Sagarminaga.R, Tiscar.S.G. (2002). Cetacean distribution related with depth and
slope in the Mediterranean waters of southern Spain. Deep Sea Research. 49, 2053-2073.
CCW.Moore. J. (2009). Intertidal SAC monitoring, Cardigan Bay SAC, May 2007. CCW
MarineMonitoring Report, 57, 1-79.
Chilvers.B.L, Corkeron.P.J. (2001). Trawling and bottlenose dolphins’ social structure.
Proceedings of the Royal Biological Society. 268, 1901-1905.
Constantine.R, Burnton.D.H, Dennis.T. (2004). Dolphin watching boats change bottlenose
dolphin (Tursiops truncatus) behaviour. Biological Conservation. 117, 299-307.
Culloch.R.M, Robinson.K.P. (2008). Bottlenose dolphins using coastal regions adjacent to a
special area of conservation in north-east Scotland. Journal of the Marine Biological
Association of the UK. 88, 1237-1243.
Davis.R.W, Fargion.G.S, May.N, Leming.T.D, Baumgartner.M, Evans.W.E, Hansen.J.L,
Mullin.K. (1998). Physical habitat of cetaceans along the continental slope in the north
central and western Gulf of Mexico. Marine Mammal Science. 14, 490-507.
Davies.R.W, Ortiz.J.G, Ribic.C.A, Evans.W.E, Biggs.D.C, Ressler.P.H, Cady.R.B,
Leben.R.R, Mullin.K, Wursig.B. (2002). Cetacean habitat in the northern oceanic Gulf of
Mexico. Deep Sea Research. 49, 121-142.
Defran.R.H, Weller.D.W, Kelly.D.L, Espinosa.M.A. (1999). Range characteristics of pacific
coast bottlenose dolphins (Tursiops truncatus) in the southern California bight. Marine
Mammal Science. 15, 381-393.
Diaz.R.J, Solan.M, Valente.R.M. (2004) A review for classifying benthic habitats and
evaluating habitat quality. Journal of Environmental Managment. 73, 165-181.
Evans, C.D.R. (1995). Chapter 2.3 Wind and Water. In: Barne, J.H., Robson, C.F.,
Kaznowska, S.S. and Doody, J.P. (eds.) 1995. Coasts and Seas of the United Kingdom.
Region 12 Wales: Margam to Little Orme. Joint Nature Conservation Committee. 239
51
Evans.P.G.H. (1998). Biology of cetaceans of the northeast Atlantic (in relation to seismic
energy). Proceedings of the Seismic and Marine Mammal.Workshop, June 23–25, 1998,
London, UK. Available at
http://www.seawatchfoundation.org.uk/docs/Evans2002BiologyOfCetaceansNEAtlanticSeis
mic.pdf
Evans.P.G.H. (2008) Selection criteria for marine protected areas for cetaceans. Proceedings
of the Seismic and Marine Mammal.Workshop, European Cetacean Society’s 21st Annual
Conference April 2007.
Fernandez.S. (1998). Age, growth and calving season of bottlenose dolphin (Tursiops
truncatus) off coastal Texas. Fishery Bulletin. 96, 357-365.
Fragaszy.D.M, Perry.S. (2003). The biology of traditions: models and evidence. Cambridge
University Press.
Gibson.R.N. (2003). Go with the flow: tidal migration in marine animals. Hydrobiologia.
503, 153-161.
Gregory.R.P, Rowden.A.A. (2001). Behaviour patterns of bottlenose dolphins (Tursiops
truncatus) relative to tidal state, time of day, and boat traffic in Cardigan Bay, west Wales.
Aquatic Mammals. 27.2, 105-113.
Gutierrez.A,A. (2000). Surface behaviour of bottlenose dolphins is related to spatial
arrangement of prey. Marine Mammal Science. 16, 287-298.
Harzen.S. (1998). Habitat use by the bottlenose dolphin (Tursiops truncatus) in the Sado
estuary, Portugal. Aquatic Mammals. 24.3, 117-128.
Hastie.G.D, Barton.T.R, Grellier.K, Hammond.P.S, Swift.R.J, Thompson.P.M, Wilson.B.
(2003). Distribution of small cetaceans with a candidate special area of conservation;
implications for management. Journal of Cetacean Research and Management. 5, 261-266.
Hastie.G.D, Wilson.B, Wilson.L.J, Parsons.K.M, Thompson.P.M. (2004). Functional
mechanisms underlying cetacean distribution patterns: hotsopts for bottlenose dolphins are
linked to foraging. Marine Biology. 144, 397-403.
52
Hooker.S.K, Whitehead.H, Gowns.S. (1999). Marine protected area design and the spatial
and temporal distribution of cetaceans in a submarine canyon. Conservation Biology. 13, 592-
602.
Hunt.G.L. O.Coyle.K, Hoffman.S, Decker.M.B, Flint.E.N. (1996). Foraging ecology of short-
tailed shearwaters near the Pribilof islands, Bering Sea. Marine Ecology Progress Series.
141, 1-11.
Ingram.S.N, Rogan.E. (2002). Identifying critical areas and habitat preferences of bottlenose
dolphins (Tursiops truncatus). Marine Ecology Progress Series. 244, 247-255.
Jackobsson.M, Macnab.R, Mayer.L, Anderson.R, Edwards.M, Hatzky.J, Schenke.H.W,
Johnson.P. (2008). An improved bathymetric portrayal of the Arctic Ocean: implications for
ocean modelling and geological, geophysical and oceanographic analysis. Geophysical
research letters. 35, 1-5.
JNCC; Connor.D.W, Gilliland.P.M, Golding.N, Robinson.P,Todd.D, Verling. E. (2006).
UKSeaMap: the mapping ofseabed and water column features of UK seas. Joint Nature
Conservation Committee, Peterborough.
Johnston.D.W. (2002). The effect of acoustic harassment devices on harbour porpoises
(Phocoena phocoena) in the bay of Fundy, Canada. Biological Conservation. 108, 113-118.
Johnston.D.W, Westgate.A.J, Read.A.J. (2005). Effects of fine scale oceanographic features
on the distribution and movements of harbour porpoises (Phocoena phocoena) in the bay of
Fundy. Marine Ecology Progress Series. 295, 279-293.
Kenny.A.J, Cato.I, Desprez.M, Fader.G, Schuttenhelm.R.T.E, Side.J. (2003). An overview of
seabed mapping technologies in the context of marine habitat classification. Journal of
Marine Science. 60, 411-418.
Kostylev.V.E, Todd.B.J, Fader.G.B.J, Courtney.R.C, Cameron.G.D.M, Pickrill.R.A. (2001).
Benthic habitat mapping on the scotian shelf based on multiple bathymetry, surficial geology
and seafloor photographs. Marine Ecology Progress Series. 219, 121-137.
53
Levinton,J.S.(2009) Marine Biology Function, Biodiversity,Ecology. Oxford University press, Third edition. 17-28.
Lusseau, D. (2004). The hidden cost of tourism: detecting long-term effects of tourism using
behavioural information. Ecology and Society .9, 1-10.
Mackie.A. (2007). Outer Bristol channel marine habitat study. Mapping European Seabed
Habitats. 5.2 case study, 1-13.
McGonigle.C, Brown.C, Quinn.R, Grabowski.J. (2009) Evaluation of image-based
multibeam sonar backscatter classification for benthic habitat discrimination and mapping at
Stanton Banks, UK. Estuarine, coastal and shelf science. 3, 423-437.
Mendes.S, Turrell.W, Lutkebohle.T, Thompson.P. (2002). Influence of tidal cycle and a tidal
intrusion front on the spatio temporal distribution of coastal bottlenose dolphins. Marine
Ecology Progress Series. 239, 221-229.
MESH; Coggan.R, Populus.J, White.J, Sheehan.K, Fitzpatrick.F, Piel.S. (2007). Review
of Standards and Protocols for Seabed Habitat Mapping. MESH.
Muller, Boutiere.M.H, Weaver.A, Candelon.N. (1998). Ethogram of the bottlenose dolphin
(Tursiops truncatus) with special rreference to solitary and sociable dolphins. Living
Environment. 48, 89-104
Natoli.A, Birkun.A, Aguilar,A. Lopez.A, Hoelzel.A.R. (2005). Habitat structure and the
dispersal of male and female bottlenose dolphins (Tursiops truncatus). Proceedings of the
Royal Society of Biology. 272, 1217-1226.
Norris.K.S, Prescott.J.H, Asa-Dorian.P.V, Perkins.P. (1961) An experimental demonstration
of echolocation behaviour in the porpoise. Biology Bulletin. 120, 163-176.
Norris.K.S, Dohl.T.P. (1980) Behaviour of Hawaiian spinner dolphin (Stenella longirostris).
Fishery Bulletin. 77, 821-849.
Pesante.G, Evans.P.G.H, Anderwald.P, Powell.D, McMath.M. (2008). Connectivity of
bottlenose dolphins in Wales: north Wales photo monitoring interim report. CCW Marine
Monitoring report. 62, 6-41.
54
Pierpoint.C, Allan.L, Arnold.H, Evans, Perry.S, Wilberforce.L, Baxter.J. (2009). Monitoring
important coastal sites for bottlenose dolphins in Cardigan Bay, UK. Journal of the Marine
Biological Association of the United Kingdom. 89, 1033-1043.
Redifern.J.V, Ferguson.M.C, Becker.E.A, Hyrenbach, Good.C, Barlow.J, Kaschner.K,
Baumgartner.M.F, Froney.K.A, Ballance.L.T, Fauchald.P, Halpin.P, Hamazaki.T,
Pershing.A.J, Qian.S.S, Read.A, Reilly.S.B, Torres.L, Werner.F. (2006). Techniques for
cetacean habitat modelling. MarineEcology Progress Series. 310, 271-295.
Selzer.L.A, Payne.P.M. (1998). The distribution of white-sided (Lagenorhynchus acutus) and
common dolphins (Delphinus delphis) vs. environmental features of the continental shelf of
the north-eastern United States. Marine Mammal Science. 4, 141-153.
Shane.S.H. (1995). Behaviour patterns of pilot whales and Risso’s dolphins off Santa
Catalina Island, California. Aquatic Mammals. 21.3, 195-197.
Scott.M.D, Wells.R.S, Irvine.B.A. (1990). A long term study on bottlenose dolphins on the
west coast of Florida. In: TheBottlenose Dolphin (Leatherwood S, Reeves RR, eds). San
Diego:Acedemic Press, 235-244.
Tetley.M.J. (2004). The distribution and habitat preference of the North Atlantic Minke
whale (Balaenoptera acutorostrata acutorostrata) in the southern Outer Moray Firth.
Dissertation thesis. University of Wales, Bangor.
Walton.C.L. (1913). The shore fauna of Cardigan Bay. Journal of the Marine Biological
Association of the Untied Kingdom (New Series). 10, 102-113.
Weir.C.R,Stockin.K.A. (2001). The occurrence and distribution of bottlenose dolphins
(Tursiops truncatus) and other cetacean species in the coastal waters of Aberdeenshire,
Scotland. Sea Watch Foundation.
Wilson.B, Thompson.P.M, Hammond.P.S. (1997). Habitat use by bottlenose dolphins:
seasonal distribution and stratified movement patterns in the Moray Firth, Scotland. Journal
of Applied Ecology. 34, 1365-1374.
Wursig.B, Wursig.M. (1979). Behaviour and ecology of the bottlenose dolphin (Tursiops
truncatus) in the south Atlantic. Fishery Bullentin. 77, 399-412.
55
Yen.P.W, Sydeman.W.J, Hyrenbach.K.D. (2004). Marine bird and cetacean associations with
bathymetric habitats and shallow-water topographies: implications for trophic transfer and
conservation. Science Direct. 50, 79-99.
56
Appendix 1
Additional OLEX and Arc Map images.
Fig.1 Olex image displaying the entire transect survey area.
57
Fig. 2 Arc map image indicating the pilot area for the boat transects.
Fig.3 Arc map data uploaded into Google Earth to provide an alternative image indicating the pilot area for the boat transects.
58
Depth (Meters)
Fig.4A Image developed on Arc map, region of the gully feature outlined and the other additional deep point off New Quay headland. Yellow diamonds represent foraging and feeding Tursiops truncates sightings.
59
Fig.4B Alternative OLEX image to display the gully features off New Quay headland.
60
Fig. 5 Close-up image indicating the depth range from approximately 9m down to 29m. Yellow diamonds indicating no T. truncates feeding or foraging directly over deeper regions.
61
Fig.6 OLEX image indicating the same deep region as seen in Fig.5 , OLEX image indicates the sediment composition is fine sand.
Fig.7 OLEX image displaying the variety of sediment composition off New Quay headland, rock, sand, gravel and fine sand .
62
Fig.8 OLEX image to show the Ynys-Lochtyn headland region of the gradually sloping seabed.
Fig.9 Close-up image of Fig. 8, also indicating sediment composition around Ynys-Lochtyn is sand.
63
Appendix 2
Raw sightings information provided on CD; excel 2010 sightings data collected during May-Aug, and the raw sightings and behavioural data used for tide analysis.
The following Mini tab output data is for the all the statistical analysis carried out on the feeding behaviour alone.
Test for Equal Variances: Total feeding versus sprig(1)/neap(2), ebb(1)/flow(2) 95% Bonferroni confidence intervals for standard deviations sprig(1)/neap(2) tide ebb(1)/flow(2) N Lower StDev Upper 1 1 59 0.249049 0.304841 0.390255 1 2 26 0.369745 0.496139 0.739757 2 1 56 * 0.000000 * 2 2 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus sprig(1)/neap(2) tide, ebb(1)/fl Test for Equal Variances: Total feeding versus ebb(1)/flow(2), Log10Spring/neap 95% Bonferroni confidence intervals for standard deviations ebb(1)/flow(2) Log10Spring/neap N Lower StDev Upper 1 0 59 0.249049 0.304841 0.390255 1 0.301030 56 * 0.000000 * 2 0 26 0.369745 0.496139 0.739757 2 0.301030 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus ebb(1)/flow(2), Log10Spring/neap Test for Equal Variances: Total feeding versus Log10Spring/neap, Log10Ebb/flow 95% Bonferroni confidence intervals for standard deviations Log10Spring/neap Log10Ebb/flow N Lower StDev Upper 0 0 59 0.249049 0.304841 0.390255 0 0.301030 26 0.369745 0.496139 0.739757 0.301030 0 56 * 0.000000 *
64
0.301030 0.301030 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus Log10Spring/neap, Log10Ebb/flow Test for Equal Variances: Total feeding versus Lnspring/neap, ebb(1)/flow(2) 95% Bonferroni confidence intervals for standard deviations Lnspring/neap ebb(1)/flow(2) N Lower StDev Upper 0 1 59 0.249049 0.304841 0.390255 0 2 26 0.369745 0.496139 0.739757 0.693147 1 56 * 0.000000 * 0.693147 2 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus Lnspring/neap, ebb(1)/flow(2) ————— 09/03/2011 10:58:56 ———————————————————— Welcome to Minitab, press F1 for help. Retrieving project from file: 'C:\USERS\HANNAH\DESKTOP\DISSERTATION\EFFORT AND SIGHTINGS DATA\TIDE ANALYSIS\MINITAB TIDE AND FEEDING.MPJ' Test for Equal Variances: Total feeding versus LN(spring/neap), LN(Ebb/Flow) 95% Bonferroni confidence intervals for standard deviations LN(spring/neap) LN(Ebb/Flow) N Lower StDev Upper 0 0 59 0.249049 0.304841 0.390255 0 0.693147 26 0.369745 0.496139 0.739757 0.693147 0 56 * 0.000000 * 0.693147 0.693147 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus LN(spring/neap), LN(Ebb/Flow) Test for Equal Variances: Total feeding versus SQRT(Spring/Neap, SQRT(Ebb/Flow)
65
95% Bonferroni confidence intervals for standard deviations SQRT(Spring/Neap) SQRT(Ebb/Flow) N Lower StDev Upper 1 1 59 0.249049 0.304841 0.390255 1 1.41421 26 0.369745 0.496139 0.739757 1.41421 1 56 * 0.000000 * 1.41421 1.41421 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus SQRT(Spring/Neap), SQRT(Ebb/Flow I Test for Equal Variances: Total feeding versus Expo(spring/Neap, SQRT(Ebb/Flow) 95% Bonferroni confidence intervals for standard deviations Expo(spring/Neap) SQRT(Ebb/Flow) N Lower StDev Upper 2.71828 1 59 0.249049 0.304841 0.390255 2.71828 1.41421 26 0.369745 0.496139 0.739757 7.38906 1 56 * 0.000000 * 7.38906 1.41421 41 0.397526 0.504854 0.684455 Bartlett's Test (Normal Distribution) Test statistic = 14.18, p-value = 0.001 Levene's Test (Any Continuous Distribution) Test statistic = 17.82, p-value = 0.000 Test for Equal Variances: Total feeding versus Expo(spring/Neap), SQRT(Ebb/Flow ————— 26/03/2011 11:49:31 ———————————————————— Welcome to Minitab, press F1 for help. Retrieving project from file: 'C:\USERS\HANNAH\DESKTOP\DISSERTATION\EFFORT AND SIGHTINGS DATA\TIDE ANALYSIS\MINITAB TIDE AND FEEDING.MPJ' Kruskal-Wallis Test: Total feeding versus sprig(1)/neap(2) tide Kruskal-Wallis Test on Total feeding sprig(1)/neap(2) tide N Median Ave Rank Z 1 85 0.000000000 91.1 -0.09 2 97 0.000000000 91.8 0.09 Overall 182 91.5 H = 0.01 DF = 1 P = 0.929 H = 0.02 DF = 1 P = 0.896 (adjusted for ties) Kruskal-Wallis Test: Total feeding versus ebb(1)/flow(2)
66
Kruskal-Wallis Test on Total feeding ebb(1)/flow(2) N Median Ave Rank Z 1 115 0.000000000 78.7 -4.28 2 67 0.000000000 113.4 4.28 Overall 182 91.5 H = 18.30 DF = 1 P = 0.000 H = 39.28 DF = 1 P = 0.000 (adjusted for ties) Kruskal-Wallis Test: Total feeding versus Log10Spring/neap Kruskal-Wallis Test on Total feeding Log10Spring/neap N Median Ave Rank Z 0.00000 85 0.000000000 91.1 -0.09 0.30103 97 0.000000000 91.8 0.09 Overall 182 91.5 H = 0.01 DF = 1 P = 0.929 H = 0.02 DF = 1 P = 0.896 (adjusted for ties) Kruskal-Wallis Test: Total feeding versus Log10Ebb/flow Kruskal-Wallis Test on Total feeding Log10Ebb/flow N Median Ave Rank Z 0.00000 115 0.000000000 78.7 -4.28 0.30103 67 0.000000000 113.4 4.28 Overall 182 91.5 H = 18.30 DF = 1 P = 0.000 H = 39.28 DF = 1 P = 0.000 (adjusted for ties) ————— 30/03/2011 10:54:17 ———————————————————— Welcome to Minitab, press F1 for help. Retrieving project from file: 'F:\DISSERTATION\EFFORT AND SIGHTINGS DATA\TIDE ANALYSIS\MINITAB TIDE AND FEEDING 2.MPJ' General Linear Model: Total feedin versus ebb(1)/flow(, sprig(1)/nea Factor Type Levels Values ebb(1)/flow(2) fixed 2 1, 2 sprig(1)/neap(2) tide fixed 2 1, 2 Analysis of Variance for Total feeding, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F ebb(1)/flow(2) 1 6.1345 5.7037 5.7037 46.70 sprig(1)/neap(2) tide 1 0.0623 0.0054 0.0054 0.04 ebb(1)/flow(2)*sprig(1)/neap(2) tide 1 0.3336 0.3336 0.3336 2.73 Error 178 21.7388 21.7388 0.1221 Total 181 28.2692 Source P ebb(1)/flow(2) 0.000 sprig(1)/neap(2) tide 0.834 ebb(1)/flow(2)*sprig(1)/neap(2) tide 0.100 Error
67
Total S = 0.349468 R-Sq = 23.10% R-Sq(adj) = 21.80% Unusual Observations for Total feeding Total Obs feeding Fit SE Fit Residual St Resid 19 1.00000 0.10169 0.04550 0.89831 2.59 R 70 1.00000 0.10169 0.04550 0.89831 2.59 R 79 1.00000 0.10169 0.04550 0.89831 2.59 R 80 1.00000 0.10169 0.04550 0.89831 2.59 R 103 1.00000 0.10169 0.04550 0.89831 2.59 R 104 1.00000 0.10169 0.04550 0.89831 2.59 R R denotes an observation with a large standardized residual. ————— 10/04/2011 11:43:55 ———————————————————— Welcome to Minitab, press F1 for help. Retrieving project from file: 'F:\DISSERTATION\EFFORT AND SIGHTINGS DATA\TIDE ANALYSIS\MINITAB TIDE AND FEEDING 2.MPJ'
SQRT(Spring/Neap) SQRT(Ebb/Flow)
1.41421
1.00000
1.41421
1.00000
1.41421
1.00000
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 14.18P-Value 0.001
Test Statistic 17.82P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
Log10Spring/Neap Log10Ebb/Flow
0.301030
0.000000
0.301030
0.000000
0.301030
0.000000
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 17.84P-Value 0.000
Test Statistic 16.84P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
68
sprig(1)/neap(2) tide ebb(1)/flow(2)
2
1
2
1
2
1
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 14.18P-Value 0.001
Test Statistic 17.82P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
sprig(1)/neap(2) tide ebb(1)/flow(2)
2
1
2
1
2
1
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 17.84P-Value 0.000
Test Statistic 16.84P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
ebb(1)/flow(2) Log10Spring/neap
2
1
0.301030
0.000000
0.301030
0.000000
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 14.18P-Value 0.001
Test Statistic 17.82P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
69
Log10Spring/neap Log10Ebb/flow
0.301030
0.000000
0.301030
0.000000
0.301030
0.000000
0.80.70.60.50.40.30.295% Bonferroni Confidence Intervals for StDevs
Test Statistic 14.18P-Value 0.001
Test Statistic 17.82P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total feeding
The following Mini tab output data is for the all the statistical analysis carried out on the foraging behaviour alone.
Test for Equal Variances: Total foragi versus sprig(1)/nea, ebb(1)/flow( 95% Bonferroni confidence intervals for standard deviations sprig(1)/neap(2) tide ebb(1)/flow(2) N Lower StDev Upper 1 1 114 0.159289 0.184814 0.219400 1 2 40 0.173326 0.220721 0.300567 2 1 126 * 0.000000 * 2 2 46 0.319722 0.401085 0.533196 Bartlett's Test (Normal Distribution) Test statistic = 45.74, p-value = 0.000 Levene's Test (Any Continuous Distribution) Test statistic = 10.83, p-value = 0.000 Test for Equal Variances: Total foraging versus sprig(1)/neap(2) tide, ebb(1)/f Test for Equal Variances: Total foraging versus Ln Spring neap, Ln ebb flow 95% Bonferroni confidence intervals for standard deviations Ln Spring neap Ln ebb flow N Lower StDev Upper 0 0 114 0.159289 0.184814 0.219400 0 0.301030 40 0.173326 0.220721 0.300567 0.301030 0 126 * 0.000000 * 0.301030 0.301030 46 0.319722 0.401085 0.533196 Bartlett's Test (Normal Distribution) Test statistic = 45.74, p-value = 0.000
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Levene's Test (Any Continuous Distribution) Test statistic = 10.83, p-value = 0.000 Test for Equal Variances: Total foraging versus Ln Spring neap, Ln ebb flow Kruskal-Wallis Test: Total foraging versus sprig(1)/neap(2) tide Kruskal-Wallis Test on Total foraging sprig(1)/neap(2) tide N Median Ave Rank Z 1 154 1.000 164.6 0.21 2 172 1.000 162.5 -0.21 Overall 326 163.5 H = 0.04 DF = 1 P = 0.835 H = 0.33 DF = 1 P = 0.566 (adjusted for ties) Kruskal-Wallis Test: Total foraging versus ebb(1)/flow(2) Kruskal-Wallis Test on Total foraging ebb(1)/flow(2) N Median Ave Rank Z 1 240 1.000 168.3 1.53 2 86 1.000 150.2 -1.53 Overall 326 163.5 H = 2.34 DF = 1 P = 0.126 H = 17.79 DF = 1 P = 0.000 (adjusted for ties) General Linear Model: Total foragi versus ebb(1)/flow(, sprig(1)/nea Factor Type Levels Values ebb(1)/flow(2) fixed 2 1, 2 sprig(1)/neap(2) tide fixed 2 1, 2 Analysis of Variance for Total foraging, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F ebb(1)/flow(2) 1 0.78346 0.69880 0.69880 17.31 sprig(1)/neap(2) tide 1 0.01271 0.19267 0.19267 4.77 ebb(1)/flow(2)*sprig(1)/neap(2) tide 1 0.51486 0.51486 0.51486 12.75 Error 322 12.99878 12.99878 0.04037 Total 325 14.30982 Source P ebb(1)/flow(2) 0.000 sprig(1)/neap(2) tide 0.030 ebb(1)/flow(2)*sprig(1)/neap(2) tide 0.000 Error Total S = 0.200920 R-Sq = 9.16% R-Sq(adj) = 8.32% Unusual Observations for Total foraging Total Obs foraging Fit SE Fit Residual St Resid
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32 0.00000 0.80435 0.02962 -0.80435 -4.05 R 49 0.00000 0.80435 0.02962 -0.80435 -4.05 R 55 0.00000 0.80435 0.02962 -0.80435 -4.05 R 56 0.00000 0.80435 0.02962 -0.80435 -4.05 R 57 0.00000 0.80435 0.02962 -0.80435 -4.05 R 72 0.00000 0.95000 0.03177 -0.95000 -4.79 R 106 0.00000 0.96491 0.01882 -0.96491 -4.82 R 117 0.00000 0.96491 0.01882 -0.96491 -4.82 R 136 0.00000 0.96491 0.01882 -0.96491 -4.82 R 178 0.00000 0.95000 0.03177 -0.95000 -4.79 R 187 0.00000 0.96491 0.01882 -0.96491 -4.82 R 220 0.00000 0.80435 0.02962 -0.80435 -4.05 R 299 0.00000 0.80435 0.02962 -0.80435 -4.05 R 302 0.00000 0.80435 0.02962 -0.80435 -4.05 R 303 0.00000 0.80435 0.02962 -0.80435 -4.05 R R denotes an observation with a large standardized residual. ————— 10/04/2011 11:48:19 ———————————————————— Welcome to Minitab, press F1 for help. Retrieving project from file: 'F:\DISSERTATION\EFFORT AND SIGHTINGS DATA\TIDE ANALYSIS\TIDE AND FORAGING.2.MPJ'
sprig(1)/neap(2) tide ebb(1)/flow(2)
2
1
2
1
2
1
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
95% Bonferroni Confidence Intervals for StDevs
Test Statistic 45.74P-Value 0.000
Test Statistic 10.83P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total foraging
Ln Spring neap Ln ebb flow
0.301030
0.000000
0.301030
0.000000
0.301030
0.000000
0.550.500.450.400.350.300.250.200.1595% Bonferroni Confidence Intervals for StDevs
Test Statistic 45.74P-Value 0.000
Test Statistic 10.83P-Value 0.000
Bartlett's Test
Levene's Test
Test for Equal Variances for Total foraging
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The following Mini tab output data is for the all the statistical analysis carried out on the Milling behaviour alone.
Results for: milling Mann-Whitney Test and CI: epp, flow N Median epp 7 1.000 flow 2 4.500 Point estimate for ETA1-ETA2 is -3.500 94.3 Percent CI for ETA1-ETA2 is (-5.000,-2.000) W = 28.0 Test of ETA1 = ETA2 vs ETA1 not = ETA2 is significant at 0.0570 The test is significant at 0.0509 (adjusted for ties)
The following Mini tab output data is for the all the statistical analysis carried out on the Leaping behaviour alone.
Mann-Whitney Test and CI: spring, neap N Median spring 21 3.000 neap 15 2.000 Point estimate for ETA1-ETA2 is 0.000 95.3 Percent CI for ETA1-ETA2 is (-0.000,1.000) W = 422.0 Test of ETA1 = ETA2 vs ETA1 not = ETA2 is significant at 0.2897 The test is significant at 0.2634 (adjusted for ties) Mann-Whitney Test and CI: ebb, flow N Median ebb 26 2.500 flow 10 3.500 Point estimate for ETA1-ETA2 is -1.000 95.0 Percent CI for ETA1-ETA2 is (-2.000,0.000) W = 441.5 Test of ETA1 = ETA2 vs ETA1 not = ETA2 is significant at 0.1684 The test is significant at 0.1457 (adjusted for ties)
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