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Global Vision International Seychelles, Mahe Island Science Report 2012
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Global Vision International, Seychelles - Mahé Report Series No. 121
ISSN 1751-2255 (Print)
GVI Seychelles – Mahé
Marine Conservation Expedition
January - June 2012
GVI Seychelles – Mahé / Marine Conservation Expedition Report January - June 2012
Submitted in whole to
Global Vision International
Seychelles National Parks Authority (SNPA)
Produced by
Lee Cassidy – Science Coordinator
Grace Frank – Science Coordinator
And
Rowana Walton Expedition Leader Christophe Mason-Parker Country Director
Elizabeth Harris Expedition Staff Emily Allen Dive Instructor
Joe Daniels Expedition Staff Tessa Turnbull Scholar
Alexander Crawford Scholar Lee Bush Scholar
Chris Petchey Scholar Susie Lilley Scholar
Thank you also to our hardworking volunteers for the collection of all data;
Nadia Aamoum, Michael Ashbrook, Robin Bater, Ann-Sophie Behrendt, Eva Blaas, Jordan Bonnett,
Sophie Borner, Charlotte Broadhead, Andy Burkinshaw, Emmalee Carr, Rebecca Chan, John Clark,
Julia Constable, Adam Crowther, Danielle Curtis, Glyn Curtis, Thomas Daly, Simon Delabays,
Annalisa DiTano, Matthew Fletcher, Kimberley Gardiner, Callum Gilbert, Allison Goodman, James
Goodman, Sean Hanczor, Louie Heist, Ash Hemraj, Ellis Howes, Brianna Jones-Mattes, Johan
Karlsson, Louise Kendall, Muhammad Khalis, Oliver Leamon, Qing Loh, Tove Lundgren, Phil
Maxam, Amelia McGowan-Whelan, Christopher McGrath, Markus Mehrwald, Bärbel Meister, Isobel
Mitic, Whitney Moore, Christopher Naco, Paul Nauta, Josh Oliphant, Bronwyn Palmer, Sarah Pevey,
Carly Reeves, Nicole Ryan, Andrew Scoon, Simon Sinclair, Mark Smith, Yanni Smith, Muriel
Stirnimann, Patrick Sukop, Tom Sweet, Marie-Louise Therkelsen, John Colin Thielan, Sarah
Thomas, Tina Thorburn, Tara Tibshirani, Leanne Van Niekerk, Daniel Wilson & May Yap.
GVI Seychelles – Mahé / Marine Conservation Expedition
Address: GVI c/o SNPA, PO Box 1240, Victoria, Mahé, Seychelles
Email: [email protected] Web page: http://www.gvi.co.uk and http://www.gviusa.com
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Abstract
The survey period for GVI coral reef monitoring was revised with the income of 2012;
wherein instead of completing set phases of individual monitoring, GVI monitors all fish,
coral and invertebrates on a year-round basis to analyse the state of the reefs as a whole.
Within the first six months of the year coral surveys are to focus on coral and epibenthic
organism coverage, with the second six months dedicated to monitoring recruitment rates
for scleractinian coral. Methodologies for both fish and invertebrates are the same for the
entire 12-month period. Additionally, all survey sites are now considered 'core' sites so the
full complement of 24 sites are monitored on a rotational basis twice per year.
Surveys from January to June 2012 examined coverage of all epibenthic organisms, as
well as scleractinian coral diversity, density of both reef and commercial fish species and
the abundance of key indicator invertebrate species. All sites were completed.
Overall results gained from January to June 2012 show coral cover has increased reaching
36.42% (SE ±1.78); the highest coverage seen yet in the monitoring program. This
increase is seen over both carbonate and granitic reefs where coral increased by the same
amount on both substrates. Analysis of the structural complexity shows that branching coral
coverage increased again this year maintaining its dominance from 2011. This continued
increase in the growth of the physical matrix of the reefs is a very positive sign for the future
of these reefs being able to support a wider diversity of life.
Coverage of all other epibenthic organisms show steady increases across all sites;
carbonate reefs display a much greater spread in coverage of sessile organisms and are
dominated by corallimorphs and zoanthids. Conversely, granitic reefs record sessile
organisms at much lower densities, predominantly under 3- 4% coverage, with the
exception of coralline algae, which has been decreasing in coverage since a maximum
seen in 2006.
Fish results seem to have stabilised over the past two years of surveying, with density
levels, diversity and feeding guilds recording insignificant changes. Only a few minor
fluctuations occurred within the results; with obligate corallivore species within the
Chaetodontid, Butterflyfish, family again increasing in density to be the second-most
dominant feeding guild overall. Marine Protected Areas continued to hold the highest
density of fish per m², regardless of substrate composition, and highlighted again the need
to maintain correct management of these critical areas.
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Contents
1. Introduction................................................................................................................................ 9
1.1. Survey Sites....................................................................................................................... 11
2. Aims........................................................................................................................................... 12
2.1. Species Lists...................................................................................................................... 12
2.1.1. Coral.......................................................................................................................... 12
2.1.2. Fish............................................................................................................................ 12
2.1.3. Invertebrates..............................................................................................................13
2.2. Training.............................................................................................................................. 13
2.2.1. Dive Training..............................................................................................................13
2.2.2. Survey Methodology..................................................................................................14
3. Methodology............................................................................................................................... 14
3.1. Coral.................................................................................................................................. 14
3.1.1 Line Intercept Transects (LIT)....................................................................................14
3.1.2 Coral Diversity Belt Transccts....................................................................................15
3.2. Fish.................................................................................................................................... 15
3.2.1 Stationary Point Count...............................................................................................15
3.2.2 50m Belt Transects....................................................................................................16
3.3. Invertebrates...................................................................................................................... 16
3.3.1 10m Belt Transect......................................................................................................16
3.3.2 50m Belt Transect......................................................................................................16
3.4. Environmental Parameters................................................................................................18
4. Results....................................................................................................................................... 19
4.1. Surveys Completed............................................................................................................19
4.2. Percentage mean live hard coral cover..............................................................................19
4.3. Benthic Assemblage..........................................................................................................20
4.4. Structural Complexity.........................................................................................................23
4.5 Coral Diversity................................................................................................................... 25
4.6 Overall Fish Results...........................................................................................................26
4.7 Combined Fish Density 2005 – 2012.................................................................................26
4.8 Fish Densities with regards to Feeding Guilds...................................................................28
4.9 Influence of Marine Protected Areas on Fish Densities 2005 – 2012.................................29
4.10 Fish Species Diversity........................................................................................................30
4.11 Commercial Fish Sizing Results........................................................................................32
4.12 Invertebrate Densities from 10m Transects.......................................................................33
4
4.13 Invertebrate Densities from 50m Belts...............................................................................35
4.14 Sea Cucumber Densities...................................................................................................37
5. Discussion.................................................................................................................................. 38
5.1 Coral Surveys.................................................................................................................... 38
5.2 Fish Surveys...................................................................................................................... 41
5.3 Invertebrate Surveys..........................................................................................................45
6. Additional Ecosystem Monitoring...............................................................................................47
6.1. Turtles................................................................................................................................ 47
6.1.1. Incidental Turtle Sightings..........................................................................................47
6.1.2. Beach Patrols for Nesting Turtles..............................................................................50
6.1.3. In-water Surveys of Turtle Behaviour.........................................................................50
6.1.4. Photo Identification of Turtles.....................................................................................52
6.2. Crown of Thorns................................................................................................................53
6.3. Cetacean Sightings............................................................................................................53
6.4. Whale Shark Sightings.......................................................................................................53
6.5. Plankton Sampling.............................................................................................................54
7. Non-survey Programmes...........................................................................................................55
7.1 Extra Programmes.............................................................................................................55
7.1.1 Internships................................................................................................................. 55
7.1.2 BTEC Courses...........................................................................................................55
7.2 Community Development...................................................................................................55
7.2.1 International School Seychelles (ISS)........................................................................55
7.2.2 GVI Charitable Trust..................................................................................................56
7.2.3 National Scholarship Programme..............................................................................57
8. References................................................................................................................................. 589. Appendices................................................................................................................................. 60
Appendix A. Details of sites surveyed by GVI Seychelles – Mahé, year round. Sites in bold-type
text are located within Marine Protected Areas.............................................................................60
Appendix B. Scleractinian coral genera surveyed by GVI Seychelles - Mahé............................61
Appendix C. Fish families, genera and species surveyed by GVI Seychelles - Mahé...................62
Appendix D. Fish feeding guilds analysed by GVI Seychelles – Mahé..........................................65
Appendix E. Fish species lists divided into commercial and reef species analysed by GVI
Seychelles – Mahé........................................................................................................................ 66
Appendix F. List of invertebrate species surveyed on 50m belt transects by GVI Seychelles –
Mahé.............................................................................................................................................. 67
Appendix G. Invertebrates surveyed on 10m LIT transects by GVI Seychelles – Mahé................68
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Figures List
FIGURE 1. 1. LOCATION AND SUBSTRATE TYPE OF GVI SURVEY SITES................................................................9
FIGURE 3. 1. LAYOUT OF CORAL LIT AND DIVERSITY BELTS AT EACH SURVEY SITE, WHERE THE SHORELINE IS
REPRESENTED BY THE TOP OF THE FIGURE AND THE DISTANCE FROM SHORE INDICATES INCREASING
DEPTH.......................................................................................................................................................16
FIGURE 3. 2. LAYOUT OF FISH SPC AND BELTS, AND 50M INVERTEBRATE TRANSECTS AT EACH SURVEY SITE,
WHERE THE SHORELINE IS REPRESENTED BY THE TOP OF THE FIGURE AND THE DISTANCE FROM SHORE
INDICATES INCREASING DEPTH................................................................................................................16
FIGURE 4.2.1. MEAN PERCENTAGE CORAL COVER (± SE) AT THE CARBONATE AND THE GRANITIC SITES, FOR
EACH SURVEY PERIOD FROM 2005 TO 2012............................................................................................19
FIGURE 4.3.1. MEAN PERCENTAGE COVERAGE FOR CORAL, ALGAE, OTHER BENTHIC ORGANISMS AND BARE
SUBSTRATE FROM ALL SITES FOR JAN – JUN 2012...................................................................................19
FIGURE 4.3.2 LARGE SCALE SPATIAL DISTRIBUTION OF PERCENTAGE COVERAGE OF CORAL, ALGAE, VARIOUS
BENTHIC ORGANISMS AND BARE SUBSTRATE ACROSS ALL SITES, RUNNING EAST TO WEST ACROSS
NORTH WEST MAHÉ FROM 2012.............................................................................................................20
FIGURE 4.3.3 MEAN PERCENTAGE COVERAGE OF ALGAE AND BENTHIC ORGANISMS ON SURVEYED
CARBONATE REEFS FROM 2005 – 2012....................................................................................................21
FIGURE 4.3.4 MEAN PERCENTAGE COVERAGE OF ALGAE AND BENTHIC ORGANISMS ON SURVEYED GRANITIC
REEFS FROM 2005 – 2012.........................................................................................................................21
FIGURE 4.4.1. PERCENTAGE COVERAGE OF HARD CORAL FOUND ACROSS ALL REEFS FURTHER DIVIDED BY
CORAL LIFEFORM PREVALENCE FROM 2005 - 2012.................................................................................22
FIGURE 4.4.2. PERCENTAGE COVERAGE OF CORAL LIFEFORM FOUND ACROSS ALL REEFS FROM 2005 – 2012
.................................................................................................................................................................23
FIGURE 4.4.3. PERCENTAGE OF CORAL LIFE FORMS ON CARBONATE SITES 2005 – 2012.................................23
FIGURE 4.4.4. PERCENTAGE OF CORAL LIFE FORM ON GRANITIC SITES FROM 2005 – 2012............................24
FIGURE 4.5.1. COMPARISON OF MEAN CORAL GENERA RICHNESS (± SE) FOR CARBONATE AND GRANITIC
SITES FROM 2005 – 2012..........................................................................................................................24
FIGURE 4.7.1. MEAN DENSITY PER M² OF ALL SURVEYED FISH SPECIES ACROSS ALL SURVEY SITES, 2005 -
2012.........................................................................................................................................................26
FIGURE 4.7.2. A COMPARISON OF MEAN DENSITY PER M² OF ALL SURVEYED FISH SPECIES BETWEEN
CARBONATE AND GRANITIC SUBSTRATE SITES, 2005 - 2012....................................................................26
6
FIGURE 4.8.1. COMPARISON OF FISH FEEDING GUILDS THROUGH DENSITY PER M² ACROSS ALL SITES, 2005 -
2012.........................................................................................................................................................27
FIGURE 4.8.2. COMPARISON OF FEEDING GUILDS THROUGH DENSITY PER M² ACROSS ALL SITES, 2005 –
2012, DISREGARDING HERBIVORES..........................................................................................................28
FIGURE 4.9.1. OVERALL MEAN DENSITY PER M OF FISH INSIDE AND OUTSIDE MARINE PROTECTED AREAS,
NOV-DEC 2005 TO JAN-JUN 2012.............................................................................................................28
FIGURE 4.9.2. MEAN DENSITY OF FISH PER M² ON CARBONATE SUBSTRATE SITES INSIDE AND OUTSIDE
MARINE PROTECTED AREAS, NOV-DEC 2005 TO JAN-JUN 2012...............................................................29
FIGURE 4.9.3. MEAN DENSITY OF FISH PER M ON GRANITIC SUBSTRATE SITES INSIDE AND OUTSIDE MARINE
PROTECTED AREAS, NOV-DEC 2005 TO JAN-JUN 2012.............................................................................29
FIGURE 4.10.1. SPECIES-RICHNESS (NUMBER OF FISH SPECIES FOUND) ACROSS ALL SURVEY SITES ALONG NW
MAHÉ, 2012. GREEN DENOTES SITES WITHIN MARINE PROTECTED AREAS AND BLUE DENOTES
UNPROTECTED SITES................................................................................................................................30
FIGURE 4.10.2. A COMPARISON OF SPECIES-RICHNESS (NUMBER OF FISH SPECIES) BETWEEN THE SAME
SITES OF NW MAHÉ IN 2005 AND IN 2012...............................................................................................30
FIGURE 4.12.1. MEAN DENSITY (INDIVIDUALS M²) OF INVERTEBRATE PHYLA AND BLACK SPINED SEA URCHINS
AT CARBONATE REEF SITES, FOR EVERY SURVEY PERIOD FROM 2005 TO 2012.......................................32
FIGURE 4.12.2. MEAN DENSITY (INDIVIDUALS M²) OF INVERTEBRATE PHYLA AND BLACK SPINED SEA URCHINS
AT GRANITIC REEF SITES, FOR EVERY SURVEY PERIOD FROM 2005 TO 2012...........................................32
FIGURE 4.12.3. MEAN DENSITY (INDIVIDUALS M²) OF INVERTEBRATE PHYLA AND BLACK SPINED SEA
URCHINS AT CARBONATE REEF SITES, FOR EVERY SURVEY PERIOD FROM 2005 TO 2012........................33
FIGURE 4.13.1. MEAN DENSITY PER M2 OF ALL SURVEYED INVERTEBRATE SPECIES ACROSS NORTH-WEST
MAHÉ, 2012..............................................................................................................................................35
FIGURE 4.13.2. A COMPARISON OF THE MEAN DENSITY PER M2 OF SHORT SPINE (ECHINOTHRIX SPP.) AND
LONG SPINE (DIADEMA SPP.) URCHINS ON GRANITIC VERSUS CARBONATE SUBSTRATE ALONG NORTH-
WEST MAHÉ, JAN - MAR 2009 TO 2012....................................................................................................36
FIGURE 4.13.3. MEAN DENSITY PER M2 OF CUSHION SEASTAR (CULCITA SPP.), CROWN OF THORNS
(ACANTHASTER PLANCI) AND THE GASTROPODS DRUPELLA SPP.............................................................36
FIGURE 4.14.1. MEAN NUMBER OF SEA CUCUMBERS RECORDED PER SITE FROM 2006 -2012........................37
FIGURE 4.14.2. DENSITY PER M2 OF INDIVIDUAL SEA CUCUMBER SPECIES ACROSS ALL SURVEY SITES OF
NORTH-WEST MAHÉ, OCT - DEC 2008 TO JAN - JUN 2012.......................................................................37
FIGURE 6.1.1. FREQUENCY OF HAWKSBILL AND GREEN TURTLE SIGHTINGS AROUND NORTH-WEST MAHÉ
FROM OCT- DEC 2005 TO APR- JUN 2012.................................................................................................37
7
FIGURE 6.1.2. MEAN CARAPACE LENGTH OF HAWKSBILL TURTLES AROUND NORTH-WEST MAHÉ FROM JAN-
MAR 2006 TO APR- JUN 2012...................................................................................................................38
8
1. Introduction
Global Vision International (GVI) Seychelles comprises of two expeditions based on the
granitic inner islands of Seychelles. One on Mahé, the largest and most heavily populated
island in the Seychelles group, located at the Cap Ternay Research Centre in Baie Ternay
National Park and one on Curieuse Island within the Curieuse national marine park, located
north of Praslin. The marine parks at which both GVI bases are located are controlled and
managed by the Seychelles National Parks Authority (SNPA). All of GVI’s scientific work in
the Seychelles is carried out on behalf of our local partners and at their request, using their
methodology; GVI supplies experienced staff, trained volunteers and equipment to conduct
research in support of their on-going work. GVI’s key partner is the Seychelles Centre for
Marine Research and Technology (SCMRT), the research arm of SNPA. Additional local
partners include the Marine Conservation Society Seychelles (MCSS) and the Seychelles
Fishing Authority (SFA).
Seychelles National Parks Authority (SNPA): A local organisation partly funded by the
government, encompassing the Seychelles Centre for Marine Research and Technology
(SCMRT) and the Marine Parks Authority (MPA). These organisations have the respective
aims of carrying out marine research in the Seychelles and of protecting the marine parks.
The coral and fish monitoring carried out for SCMRT constitutes the majority of the work
conducted by the volunteers.
Marine Conservation Society Seychelles (MCSS): A local non-governmental organisation
(NGO) that carries out environmental research in the Seychelles, currently monitoring
whale sharks, cetaceans and turtles around Mahé. GVI assists with all three of these
research programmes by documenting the presence or absence of turtles on every dive
throughout the phase, conducting in-water turtle behaviour survey dives and also turtle
nesting surveys. Along with the turtle work GVI reports incidental sightings of cetaceans
and whale sharks and undertakes weekly plankton sampling to aid with year round
monitoring of plankton levels in conjunction with the arrival of whale sharks to Mahé Island.
Seychelles Fishing Authority (SFA): The governing body which oversees the management
and regulation of commercial and artisanal fisheries in the Seychelles. This government
agency is directly concerned with setting the catch, bag and seasonal limits that apply to
local stocks on an annual basis, as well as managing the international export industry that
is generated from the harvest of fisheries across the Seychelles Exclusive Economic Zone
(EEZ).
9
In 1998, a worldwide coral bleaching event decimated much of the coral surrounding the
inner granitic islands of the Seychelles, with hard coral mortality reaching 95% in some
areas (Spencer et al. 2000). It is thought that this was caused by the high ocean
temperatures associated with an El Nino Southern Oscillation event at that time. Efforts to
monitor the regeneration of reefs in the Seychelles were initiated as part of the Shoals of
Capricorn, a three year programme started in 1998 and funded by the Royal Geographic
Society in conjunction with the Royal Society. SCMRT was set up by the Shoals of
Capricorn in an effort to ensure continuation of the work started, as well as to assist the
Marine Parks Authority (MPA) with the management of the existing marine parks. The
predominant objective for the Seychelles GVI expedition is to aid this monitoring
programme and thereby assist in the construction of management plans that will benefit the
future recovery of coral reefs in the area.
Between 2000 and the beginning of the GVI expedition in 2004 the Seychelles marine
ecosystem management program (SEYMEMP) took place, this was the most
comprehensive assessment of the coral reefs within the inner islands of the Seychelles to
date. Eighty one carbonate and granitic reef sites throughout the inner islands were
monitored using fine scale monitoring techniques. Monitoring efforts were continued by
Reefcare International, a non-governmental organisation based in Australia. The protocols
established by Reefcare International provided a foundation for those adopted by GVI.
Although GVI’s logistical constraints restrict monitoring efforts to the north-west coast of
Mahé at sites selected by SNPA.
The survey data collected by GVI volunteers allows for analysis of trends in coral reef
health seen over the past 12 years of monitoring. Along with this core research GVI
Seychelles also endeavours to aid in any of the other projects undertaken by all their
partners where it can; as it is hoped that with this help they will be able to increase their
capacity to monitor, manage and ultimately conserve the marine environment of the
Seychelles for the future.
The GVI expedition comprises of survey programs that are four, eight or twelve weeks long,
running continuously throughout the year from January - December. Within the 12 months
fish and invertebrates are surveyed continuously at all survey sites in set time periods. Line
Intercept Transects and Coral Diversity transects are undertaken in the first 6 months to
evaluate coral coverage and site diversity, and Coral Recruitment quadrats are used within
the second 6 months to survey newly recruited colonies and gain a picture of site recovery.
10
Health and Safety: The safety of all volunteers is paramount. All volunteers are given a
health and safety brief on the camp upon arrival and conservative diving guidelines are
adhered to for the duration of the expedition. In addition, volunteers complete the PADI
Emergency First Response first aid course, and are taught how to administer oxygen in the
event of a diving related incident.
1.1. Survey Sites
GVI surveys a maximum of 24 separate sites around north-west Mahé in the course of a
year (fig 1.1.).The 24 sites are surveyed twice a year; once in the first 6 months and then
again in the second half of the year. All sites are now listed as ‘core sites’ (see Appendix A
for site details). The sites are evenly divided between carbonate and granitic reefs and they
represent varying degrees of exposure to wave action and currents. Five of the sites are
within Marine Protected Areas (MPAs) where restrictions on all fishing as well as
regulations on the recreational use of the park are in place.
Figure 1. 1. Location and Substrate Type of GVI Survey Sites.
11
Each survey site is divided into ‘shallow’ and ‘deep’ zones, where the shallow zone is
defined by the depth range 1.5– 5.0m and the deep zone is defined by the depth range
5.1– 15.0m. Each site has a central point, marked by a distinctive landmark on the
coastline, and is further divided into left, centre and right areas (fig 3.1.). These areas are
loosely defined as such by their position with respect to the centre marker of the site. All
depths are standardised with respect to tidal chart datum so as to eliminate tidal influence.
2. Aims
The focus of January to June 2012 was on surveying commercial and reef fish species as
well as hard coral coverage around North-West Mahé. The specific aims of the phase were;
Assess diversity and density of fish species across all survey sites
Estimate size of commercially important fish species
Diversity of hard coral genera across all sites
Assess benthic assemblage, including evaluation of hard coral, soft coral, sessile
organisms coverage and substrate composition
Monitor coral predation and algal grazing pressures through density estimates of
hard coral predators, sea urchins and specific fish feeding guilds
Assess abundance and diversity of commercially targeted invertebrate species
including sea cucumbers, lobster and octopus
2.1. Species Lists
2.1.1. Coral
The list of surveyed scleractinian corals covers 50 separate genera (See Appendix B for
the complete species list). Corals are identified to genus level only as in situ identification
beyond genus level is not possible in the case of some corals, and is also beyond the
requirements of the project aims. Volunteers are also encouraged to record the genus as
‘unknown’ if they are not able to confidently identify a coral beyond the family level, and
similarly to record ‘unknown hard coral’ where even the family is not determinable with a
level of confidence.
2.1.2. Fish
The fish species chosen for surveys are those that are likely to indicate status of the reefs
along with fishing pressure, but are not overly difficult to locate, identify and count as
specified by SCMRT. For example, Surgeonfish are herbivores and grazers and thus would
12
influence the algal – coral dynamics within the reef ecosystem. Reef-associated species of
commercial concern are also surveyed. This data can be used to help determine the status
of the reefs and of the fisheries especially when compared with the data from previous
phases.
Fish are surveyed to the highest taxonomic resolution practicable, with most identified to
species level. The resolution depends on difficulty of identification, and also the species’
characteristics and the data requirements of our partners. The taxonomic level needed
varies according to the ecological function of the species within the ecosystem; for
example, if different species within a genus feed on different types of food, it is highly
desirable to distinguish them to species. However, volunteers are instructed to record only
to the level to which they are confident of the identification, thus if they are sure of the
family but not genus or species, they record only as an “unknown species” of that family.
See Appendix B for the list and taxonomic resolution of fish species surveyed.
2.1.3. Invertebrates
Invertebrate species which influence and can indicate the health and conditions of coral
reefs are surveyed alongside the coral genera, as well as commercially viable species
which are under fishing pressure. A full list of surveyed invertebrate species is included in
Appendix E.
2.2. Training
2.2.1. Dive Training
All volunteers must be at least PADI Open Water qualified to join the expedition.
Volunteers then receive the PADI Advanced Open Water course covering Boat, Peak
Performance Buoyancy, Navigation, Underwater Naturalist, and Deep dives. Particular
attention is paid to buoyancy as surveys are conducted in water as shallow as two metres
and over delicate reef ecosystems.
Volunteers are required to learn hard corals, with invertebrate identification an additional
aspect of the program. Training is initially provided in the form of presentations, workshops
and informal discussion with the expedition staff. Self-study materials are also available in
the form of electronic and hard copy flashcards, as well as Indian Ocean identification
publications. Knowledge is tested using pictures on land, for which a 95% pass mark is
required. Volunteers are taken on identification dives with staff members for in-water
testing; their responses are recorded and the dives continue until the volunteer has
demonstrated accurate identification of all necessary species/genera.
13
2.2.2. Survey Methodology
Volunteers receive on land briefings and lectures, navigation practice and in-water training
in the skills required to conduct reef surveys. Participants complete the PADI Coral Reef
Research Diver (CRRD) course, which is specifically developed for GVI and offered in only
one other marine expedition in the world, Mexico. All are trained in the use of a delayed
surface marker buoy and tape reels, plus any other survey equipment specific to the
research they will be conducting. The course also includes a series of lectures on various
aspects of the marine environment. Before completing any Underwater Visual Census
(UVC) independently, volunteers participate in practice UVCs in which they are taught and
supervised by a member of staff.
Improvements to the quality of species identification training materials are an ongoing and
extremely important component to this marine expedition. Photographs taken locally of
species underwater are the best materials to use – they are accurate and portray how the
organism appears underwater. New electronic and hardcopy flashcards are produced to
enhance the self-study materials available and to develop the exams by the same means.
Volunteers are encouraged to donate their underwater pictures to add to the library.
3. Methodology
3.1. Coral
1.1.1 Line Intercept Transects (LIT)
The LIT is a cost-effective method for assessing reef composition (Leujak & Ormond 2007)
which produces good results, replicates easily and can be taught to volunteers within time
and knowledge constraints. At every site, six 10 metre LITs were carried out, each running
parallel to shore along a single depth contour and using reeled tape measures. Three LITs
were completed in both the shallow and deep zones, evenly spread amongst the left,
centre and right of the site (Fig. 3.1.). Divers record a start and end depth for each transect.
The benthic assemblage and substrate is recorded in a continuous series of data of what is
directly under the tape, with start and end points for each entry, to the nearest cm. Where
coral is found, it is identified to genus level and the life form describing the majority of the
colony is recorded. Transects were laid randomly where possible, however placement of
the 2lb weight at the beginning of the transect generally meant avoiding delicate organisms,
therefore the start point would not be chosen randomly. Additionally, the topography at
some of the granitic sites creates limited possible places where 10 m of tape can be laid
14
inside the 1.5 – 5.0 m zone and meant that shallow transects must be laid wherever the
diver can achieve it and thus diver selection must drive the process.
1.1.2 Coral Diversity Belt Transccts
Two belt transects were conducted at each site to assess diversity of coral genera. The
transects started within the shallow zone at the centre of the site, heading out either to the
deep left (belt B) or to the deep right (belt A) at a 45˚ angle from shore; thus both the depth
and spread of each site is sampled (Fig 3.1). Divers conduct the survey by searching for
coral genera within 2.5m of either side of the line, completing tight s-shaped search
patterns, thus together surveying a 5m wide corridor along the 50m. Each diver records
the presence of any coral genera seen in their search area once.
3.2. Fish
1.1.3 Stationary Point Count
The stationary point count is a commonly used UVC technique (Kulbicki 1998, Engelhardt
2004) employed by well-respected reef assessment programs such as the Atlantic and Gulf
Rapid Reef Assessment (AGGRA) and the Florida Keys National Marine Sanctuary Coral
Reef Monitoring Program (FKNMS CRMP) (Hill & Wilkinson 2004). Variations of the method
have been used as part of several studies in the Seychelles (Jennings et al. 1995; Spalding &
Jarvis 2002; Engelhardt 2004; Graham et al. 2007) where the lack of spear fishing increases the
reliability of this technique (Jennings et al. 1995). The post-bleaching surveys conducted by
Reefcare International as part of the Seychelles Marine Ecosystem Management Project
(SEYMEMP) used 7 minute long stationary point counts and defined the area for the point
count with a 7m radius (Engelhardt 2001; 2004); 7– 7.5m radius circle has been shown to
create an area of the most suitable size for the size groups into which coral reef fish
typically fall (Samoilys & Gribble 1997). When GVI assumed responsibility for the
continuation of this assessment in 2005, the same methodology was adopted.
At each site eight stationary point counts were carried out. Four stationary point counts
were done in each of the shallow and deep zones, two centre, one left and one on the right
(Fig. 3.2.). Divers recorded depth at the centre of each point count and start time for each
survey. A tape measure was used to delineate the circle radius, laid in any direction along
the reef. This allows for visual reference for the census boundary, increasing accuracy for
density calculations. Point counts were conducted by buddy pairs of divers where each was
responsible for counting a different selection of surveyed fish, thus reducing the number of
fish one person is required to count. During the last minute both divers swam around the
circle to attempt to ensure that more cryptic fish were counted.
15
1.1.4 50m Belt Transects
Colvocoresses and Acosta (2007) reported that Belt Transect surveys can cover more area
with a similar observer effort than Point Count surveys, although behavioural avoidance of
fish towards divers was frequently noted and, possibly as a result, lower densities of fish
have been recorded on Belt Transects than on Point Counts. We decided to introduce Belt
Transects in addition to the Stationary Point Counts, but to incorporate mechanisms to
reduce behavioural avoidance. Variety in methodologies also has the advantages of
adding to the skills set of the Expedition Members and enhancing their experience.
The transect belts were 50m long by 5m wide, a standard area often used for reef
assessments (Samoilys & Gribble 1997; Hill & Wilkinson 2004). Surveys were conducted by
buddy pairs with each diver responsible for counting a different selection of fish. Four belt
transects were completed at each site, 2 in the deep zone and 2 in the shallow (Fig. 3.2). A
measuring tape was laid parallel to the shoreline on the reef by one diver while the other
swims in front counting fish. Samoilys and Gribble (1997) recommend this technique of
simultaneously counting fish and laying the transect tape as it avoids disturbing the fish
prior to counting. After completion of the outward stage of the transect, the observers
hover away from the end of the tape for 3 minutes to allow fish to return to the survey area
before beginning the return leg. On the return journey, the second diver swims back along
the tape counting the other fish while the buddy reels in the tape behind them.
3.3. Invertebrates
1.1.5 10m Belt Transect
The diver conducting the invertebrate belt transects dives as a buddy to the coral LIT diver
and transects are conducted along the same tape as the LITs, thus six invertebrate belts
were completed at each site (Fig. 2.2). Invertebrate divers searched the area extending to
1 m either side of the tape for targeted species (see Appendix G), covering 10*2 m total.
1.1.6 50m Belt Transect
Extent of hard coral predation was measured as the density of two types of sea star;
cushion stars (Culcita spp.) and Crown of Thorns (Acanthaster planci), and gastropods in
the genus Drupella at each survey site, all of which are hard coral predators. Algal grazing
pressure was measured as the density of sea urchins. Two 50m transects were laid out at
each site, using polyprophelene reel tape measures. The transects start at the shallow
centre point and head out at opposing 45˚ angles towards the deep zone, thus covering the
whole depth range of 1.5– 15.0m and the spread of the site. Target species within 2.5m
either side of the tape were recorded (see Appendix F).
16
Stationary point countFish belt transectInvertebrate belt
Figure 3. 1. Layout of coral LIT and diversity belts at each survey site, where the shoreline is represented by the top
of the figure and the distance from shore indicates increasing depth.
Figure 3. 2. Layout of fish SPC and belts, and 50m invertebrate transects at each survey site, where the shoreline is
represented by the top of the figure and the distance from shore indicates increasing depth.
17
B A
3.4. Environmental Parameters
During each survey dive the boat captain records abiotic factors pertaining to the
environmental conditions during the dive.
Turbidity is recorded using a Secchi disk
Cloud cover is estimated in eighths
Sea state is evaluated using the Beaufort scale, a copy of which is kept on the boat
Surface and bottom sea temperatures are recorded using personal dive computers
18
4. Results
4.1. Surveys Completed
During January to June 2012, substrate composition, commercial and reef fish species
density and mobile invertebrate density were recorded. For substrate composition surveys
22 survey sites were successfully completed, for fish density 23 survey sites were
completed out a possible 24 survey sites across the north-west Mahé coastline. Bad
weather conditions didn’t allow for a full composite of sites to be completed. Within each
site all stationary point counts, fish belts, LIT transects, coral diversity transects and
invertebrate belt transects were completed. This created a total of 184 SPCs, 92 fish belts
(51,324m²), 132 LIT transects, 44 coral diversity transects (11,132m²), 132 invertebrate
transects and 46 invertebrate density belts (14,140m²) across the 23 completed sites.
In addition to the core surveys, in-water behavioural turtle surveys were conducted weekly
as well as turtle nesting surveys within the season of January to March. Data was also
collected on incidental sightings of mega-fauna including turtles, cetaceans, sharks, rays
and invertebrates of commercial importance.
4.2. Percentage mean live hard coral cover
Percentage hard coral cover was determined from the line intersect transects. Percentage
coral cover has seen an overall increase between survey phases 2005 to 2012. Results
from 2012 found coral cover reaching maxima since surveys began at 36.42% (± 1.78)
mean live hard coral cover. Overall mean percentage cover has increased every year with
the exception on 2009.
Percentage coverage of coral has continued its increase over the years, however when
results are analysed by substrate type (Fig 4.2.1) differences in the rate of change can be
seen. Coverage on carbonate reefs has again reached its maximum coverage seen since
surveys began of 34.74%; increasing by 1.7% from 2011 the same amount as between
2010 – 2011. Coral coverage on granitic reefs reached its new maxima of 38.1%, also
returning to the positive trend found in most years as opposed to the decline in coverage
for 2011. The overall percentage coral cover remains higher for granitic reefs, continuing
the trends found since 2005. Maximum difference between the percentage cover between
the two substrates was found in 2006 at 8.23%. Although fluctuating, this gap has now
narrowed with time. Current results show a difference of just 3.36%, consistent with the
previous year’s difference of 3.33%.
19
En-gel-
hardt 2004
2005 2006 2007 2008 2009 2010 2011 20120
5
10
15
20
25
30
35
40
45
Carbonate Granitic
Mea
n Pe
rcen
tage
Cor
al C
over
% (±
SE)
Figure 4.2.1. Mean percentage coral cover (± SE) at the carbonate and the granitic sites, for each survey period from 2005
to 2012
4.3. Benthic Assemblage
Along with coverage of coral species, benthic assemblage is also recorded on the line
intersect transects. When combining the data from all sites results found for 2012 show a
higher percentage of algae at 49.54% than that of coral at 36.57%; with areas of bare
substrate (5.93%) and other benthic organisms (7.96%) showing significantly lower
coverage (Fig ). The various benthic organisms consist mainly of soft corals, sponges,
corallimorphs and zoanthids.
Coral Cover %
Algal cover %
Various %
Bare %
Figure 4.3.1. Mean percentage coverage for coral, algae, other benthic organisms and bare substrate from all sites for Jan –
Jun 2012
20
Although sites show high coverage of algae the actual distribution of coverage differs when
looking at site specifics. It is observed that sites that show low coral cover have significantly
higher algal cover; this is also true with the reverse. Willie’s Bay Reef shows the highest
algal dominance of all sites (fig. 4.3.2.).
L'ilot N
orth Fa
ce
Corsaire
Reef
Site X
Rays P
oint
Anse Majo
r Point
Willi
e's Bay
Point
Baie Te
rnay
North Ea
st
Baie Te
rnay
Centre
Baie Te
rnay
Lighthouse
Port Lau
nay W
est Rocks
There
se North
Point0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Bare %Various %Algal cover %Coral Cover %
Figure 4.3.2 Large scale spatial distribution of percentage coverage of coral, algae, various benthic organisms and bare
substrate across all sites, running East to West across North West Mahé from 2012
Excluding the continual growth seen with the Scaleractinian corals, distributions of algae
and other benthic organisms can be analysed across both the carbonate and granitic
substrates. Coverage of these benthic organisms differs between the two reef substrates.
Carbonate showing higher coverage of the different organisms whilst granitic is dominated
by coralline algal with all other species having stable low level densities (fig. 4.3.3; fig.
4.3.4).
Benthic organisms on carbonate reefs display a wide range in densities, all however are
found at significantly lower percentages than coral; below 9% coverage. Fluctuations are
seen with regards to each group, relative dominance has however remained stable
throughout the monitoring program with the exception of macro algal where this organism is
currently found as the least abundant on carbonate reefs (fig. 4.3.3). there has been a
decline in the density of the 3 most abundant benthic organisms, Corallimorphs / Zoanthids,
soft coral and coralline algal although the drop is relatively small and can be seen in
21
previous years (2008, 2009 and 2010 with respect to these organisms) with subsequent
increase the following years. The trends overall are remaining stable.
2005 2006 2007 2008 2009 2010 2011 20120.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
Soft CoralSpongeCorallimorphs / ZoanthidsCoralline Algae Macro Algae
Me
an
Pe
rce
nta
ge
Co
ve
rage
%
Figure 4.3.3 Mean percentage coverage of algae and benthic organisms on surveyed carbonate reefs from 2005 – 2012.
Granitic reefs differ in the benthic assemblage from carbonate reefs wherein the spread of
coverage is dominated by Coralline Algae which consistently shows higher percentage
cover than all other benthic organisms (with the exception of coral). Percentage coverage
has seen a marked reduction from the peak at 10.56% in 2006. Current coverage found for
2012 is 5.19% yet this organism still remains dominant. All other surveyed benthic
organisms have shown consistent low level coverage of below 4% with little fluctuation in
coverage throughout the phases (fig. 4.3.4).
2005 2006 2007 2008 2009 2010 2011 20120.00
2.00
4.00
6.00
8.00
10.00
12.00
Soft CoralSpongeCorallimorphs / ZoanthidsCoralline Algae Macro Algae
Me
an P
erc
en
tage
Co
vera
ge %
Figure 4.3.4 Mean percentage coverage of algae and benthic organisms on surveyed granitic reefs from 2005 – 2012.
22
4.4. Structural Complexity
Structural complexity of the reefs is derived from the coverage of coral life forms which
increase the physical matrix of the reefs; primarily the branching and sub massive life
forms. Encrusting and massive coral life forms, although responsible for building up the reef
structure, provided limited habitat space for other reef inhabitants. The coverage of coral
life forms is independent from abundance of coral genus as a single genus can exhibit a
multitude of life forms.
2005 2006 2007 2008 2009 2010 2011 20120
5
10
15
20
25
30
35
40
MushroomSubmassiveMassiveFolioseEncrustingBranching
Figure 4.4.1. Percentage coverage of hard coral found across all reefs further divided by coral lifeform prevalence from 2005
- 2012
Figure 4.4.1 shows that across all sites the percentage coverage of coral has increased,
along with this there have been changes in the abundance of the key life forms related to
the structural complexity of the reefs.
Figure 4.4.2 shows the changes in the percentage coverage of life forms across all reefs.
Increase in the branching corals is clearly identifiable through the monitoring program. In
2005 branching corals made up 6.13% of the total coral cover, whereas encrusting coral
was dominating the reefs at this time with 49.94% of coral found in this life form. Branching
corals have increased year on year since monitoring began. In 2011 branching coral
became the dominant coral life form; results in 2012 show a continuation of this dominance.
Results from 2012 show branching corals making up 43.03% of hard coral cover whereas
encrusting has fallen to 29.17%. Massive coral life forms have also decreased in coverage
from 2005 – 2012. Significantly sub massive corals have seen an increase in cover
23
although at a much slower rate than that of the branching life form; increasing from 3.97%
in 2005 to 9.56% in 2012.
2005 2006 2007 2008 2009 2010 2011 20120
10
20
30
40
50
60
70
80
90
100
MushroomSubmassiveMassiveFolioseEncrustingBranching
Pe
rce
nta
ge
co
ve
r o
f co
ral life
form
s %
Figure 4.4.2. Percentage coverage of coral lifeform found across all reefs from 2005 – 2012
Overall distribution of lifeform differs significantly depending on substrate type. Branching
lifeforms dominate the carbonate reefs whereas encrusting lifeforms dominate the granitic
(fig 4.4.4). The higher rate of growth in the branching corals on the carbonate reefs is the
reason for the dominance. Granitic reefs have displayed increased coverage of branching
corals however the rate is markedly slower than that seen on the carbonate reefs (fig
4.4.3).
2005 2006 2007 2008 2009 2010 2011 20120
10
20
30
40
50
60
70
80
90
100
MushroomSubmassiveMassiveFolioseEncrustingBranching
Me
an
Pe
rce
nta
ge
Co
ve
rage
%
Figure 4.4.3. Percentage of coral life forms on carbonate sites 2005 – 2012
24
2005 2006 2007 2008 2009 2010 2011 20120
10
20
30
40
50
60
70
80
90
100
MushroomSubmassiveMassiveFolioseEncrustingBranching
Me
an
Pe
rce
nta
ge
Co
ve
rage
%
Figure 4.4.4. Percentage of coral life form on granitic sites from 2005 – 2012
1.2 Coral Diversity
Survey of coral diversity found a total of 43 different genera from 14 families of
Scleractinian corals for 2012. Figure 4.5.1 shows the mean number of genus found at each
site, divided by substrate type. Results found mean coral diversity across all sites to be
31.30 coral genera per site. From 2005 an initial increase in coral diversity is seen which
continued until 2007, from this point on coral genera have remained stable at around a
mean of 31 per site. Throughout the surveys the difference between diversity at both the
granitic and carbonate reefs has been relatively stable, which is seen in the 2012 results.
For 2012 granitic sites showed a mean coral diversity of 31.18 and carbonate sites showed
31.10 genera per site.
2005 2006 2007 2008 2009 2010 2011 20120.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
Carbonate Granitic
Me
an G
en
era
Ric
hn
ess
pe
r si
te(
±SE)
Figure 4.5.1. Comparison of mean coral genera richness (± SE) for carbonate and granitic sites from 2005 – 2012.
25
1.3 Overall Fish Results
Overall abundance for all surveyed commercial and reef fish species using both point count
and belt methodologies came to 15,384 individuals across a total survey area of 46,862m2,
giving an average fish density of 0.29 individuals per m2. Per specific survey site, the
highest total abundance levels were found at Baie Ternay Centre with 1,297 individuals
(0.58 per m2). The next closest site in terms of overall density was Auberge Reef with 810
individuals (0.36 per m2). The lowest abundance levels were found at Corsaire Reef, 376
individuals (0.17 per m2), and Willie’s Bay Reef, 435 individuals (0.19 m2).
Baie Ternay Centre, the site with the highest density, is central in location to GVI’s survey
area and is also a Marine Protected Area (MPA). Although liable to high levels of traffic
from both tourist charters and dive boats, the protection from fishing within this site is
arguably the highest compared to all marine protected areas around north-west Mahé. The
same comparison cannot be made for the second most abundant site, Auberge Reef, it is
subject to the same pressures as the sites usually found on the lower scale of fish
densities. Further analysis into the site’s specific densities will need to be made to
determine the huge increase in apparent fish population health at this site.
The sites found to have the lowest abundance and density levels are towards the eastern
extent of the survey sites and in close proximity to Beau Vallon and Bel Ombre harbour; an
area of high boat traffic and high artisanal fishing pressure on both the granitic and
carbonate reefs (fig. 1.1.). These sites are also not within marine protected areas.
1.4 Combined Fish Density 2005 – 2012
The data used to analyse fish abundance over all sites is taken from the stationary point
count surveys, as the belt transect was only introduced into GVI’s set survey methodology
in 2009. The analysis of all data 2011 has also been modified to adapt to the new surveyed
species list revised in 2009 and 2010, and all pre-existing data from 2005 onwards has
been adapted to represent this. This finally allows for correct interpretation of the feeding
guilds and total fish density across all of the survey years, and hence any relevant
fluctuations in density or predominance of guilds can be accurately seen.
The mean density of fish for January to June 2012 was found to be 0.29 individuals per m 2,
very similar to the findings from 2011. Minor fluctuations in density are present across all
26
years of surveys, however the density has never been seen to rise or fall outside of 0.25
and 0.35 per m2 since 2005 (fig. 4.7.1.).
2005 2006 2007 2008 2009 2010 2011 20120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Survey Year
Me
an
de
nsi
ty o
f fi
sh p
er
m2
Figure 4.7.1. Mean density per m² of all surveyed fish species across all survey sites, 2005 - 2012.
When dividing the densities between site substrate (granitic vs. carbonate) the results from
2012 show an insignificant difference between the two; granitic sites had a density of
0.2999 compared to 0.2995 per m2 within the granitic sites (fig.4.7.2.). This finding is in tune
with previous results; as minor fluctuations in substrate relative richness have occurred
across all years and the predominance of either site switches. This is interesting in itself, as
the two substrate compositions have greatly differing environments and food resources for
fish species and so would theoretically harbour varying levels of fish density per m².
2005 2006 2007 2008 2009 2010 2011 20120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Carbonate Granitic
Survey Year
Me
an
de
nsi
ty o
f fi
sh p
er
m2
Figure 4.7.2. A comparison of mean density per m² of all surveyed fish species between carbonate and granitic substrate
sites, 2005 - 2012.
27
28
1.5 Fish Densities with regards to Feeding Guilds
All data on the abundance of fish species can be analysed using feeding guilds; determined
by the primary food source of individual species. These feeding guilds and the species that
fall within them are taken from Obura and Grimsditch (2009), and further adapted to the
specific species found within Seychelles in agreement with our partners. A full list of the
relative guilds and the divided species can be found in appendices C. As with fish density
results, the density of feeding guilds is also only taken from the stationary point counts to
eliminate the consequences from the change in survey methodology in 2009.
The most dominant feeding guild across all sites is the herbivores (fig. 4.8.1.), comprising
surgeonfish (Acanthuridae), rabbitfish (Siganidae) and parrotfish (Scaridae). This guild has
remained at a relatively stable abundance during all survey years, increasing slowly in
density from 2006 onwards. 2012 has risen slightly from the drop in numbers seen in 2011;
the first downward turn for herbivores seen since 2006.
2005 2006 2007 2008 2009 2010 2011 20120
0.05
0.1
0.15
0.2
0.25
PlanktivoresPiscivorousCorallivoresVaried dietInvertivoresHerbivoresCorallivore / HerbivoreCorallivore / Invertivore
Survey Year
De
nsi
ty o
f Fi
sh S
pe
cie
s p
er
m2
Figure 4.8.1. Comparison of fish feeding guilds through density per m² across all sites, 2005 - 2012.
Figure 4.8.2 reveals the greatest change in density that has occurred for any feeding guilds
across all survey years. The corallivores, a feeding guild consisting of obligate coral
feeders within the butterflyfish family (Chaetodontidae), is the guild which has displayed the
greatest change in abundance across the survey years, from 0.001 in 2005 to 0.036 per m2
in 2011.
29
2005 2006 2007 2008 2009 2010 2011 20120
0.01
0.02
0.03
0.04
0.05
0.06
Corallivores
Piscivorous
Varied diet
Corallivore / Herbivore
Corallivore / Invertivore
Invertivores
PlanktivoresSurvey Year
De
nsi
ty p
er
m2
Figure 4.8.2. Comparison of feeding guilds through density per m² across all sites, 2005 – 2012, disregarding herbivores.
1.6 Influence of Marine Protected Areas on Fish Densities 2005 – 2012
In analysing the data between the mean density of fish per m2 within marine protected
areas (MPAs) and unprotected areas there is a consistently higher density within MPAs
(fig. 4.9.1.). With the exception of the Jan- Mar 2010 survey phase, MPAs have had an
average greater density of 0.049 per m2 ± 0.004 SE.
Nov-Dec 0
5
Apr-Jun 06
Oct-Dec 0
6
Apr-Jun 07
Oct-Dec 0
7
Apr-Jun 08
Oct-Dec 0
8
Jul-S
ept 09
Jan-Mar 1
0
Jul-S
ept 10
Jan-Mar 1
1
Jul-S
ept 11
Jan-Jun 120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Overall Protected Overall Unprotected
Survey Phases
Me
an
De
nsi
ty o
f Fis
h p
er
m2
Figure 4.9.1. Overall mean density per m of fish inside and outside marine protected areas, Nov-Dec 2005 to Jan-Jun 2012.
Separating the sites into granitic and carbonate reveals that this substrate has no influence
on mean density levels of fish; the protected sites on either type harboured a higher density
overall (fig. 4.9.2; fig. 4.9.3.). Carbonate sites within MPAs have always held a higher
density of fish since 2005, with the January – June 2012 phase containing a mean density
of 0.366 per m2 within MPAs compared to 0.287 per m2 in the carbonate sites outside
protected zones (fig. 4.9.2.).
30
Nov-Dec 0
5
Apr-Jun 06
Oct-Dec 0
6
Apr-Jun 07
Oct-Dec 0
7
Apr-Jun 08
Oct-Dec 0
8
Jul-S
ept 09
Jan-Mar 1
0
Jul-S
ept 10
Jan-Mar 1
1
Jul-S
ept 11
Jan-Jun 120.00
0.10
0.20
0.30
0.40
0.50
0.60
Carbonate Protected Carbonate Unprotected
Survey Phases
Me
an
De
nsi
tiy o
f Fis
h p
er
m²
Figure 4.9.2. Mean density of fish per m² on carbonate substrate sites inside and outside marine protected areas, Nov-Dec
2005 to Jan-Jun 2012.
Granitic sites have had a much less significant difference between the years, continuously
fluctuating in relevant densities. The January - June 2012 results show that mean density
within granitic protected sites is currently slightly higher at 0.351 per m2 compared with
0.325 per m2 outside protected zones (fig. 4.9.3.).
Nov-Dec 0
5
Apr-Jun 06
Oct-Dec 0
6
Apr-Jun 07
Oct-Dec 0
7
Apr-Jun 08
Oct-Dec 0
8
Jul-S
ept 09
Jan-Mar 1
0
Jul-S
ept 10
Jan-Mar 1
1
Jul-S
ept 11
Jan-Jun 120
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Granitic Protected Granitic Unprotected
Survey Phases
Me
an
De
nsi
ty o
f Fis
h p
er
m²
Figure 4.9.3. Mean density of fish per m on granitic substrate sites inside and outside marine protected areas, Nov-Dec 2005
to Jan-Jun 2012.
1.7 Fish Species Diversity
Diversity refers to the species-richness, or number of separate species, within the survey
site as opposed to the relative abundance of fish. The site found to have the highest
diversity in 2012 was Anse Major Point with 43 species (fig. 4.10.1.). The lowest diversity
was found at Port Launay South Reef with 26 species and Conception Central East Face
with 27 (fig. 4.10.1.). In addition, comparing sites inside Marine Protected Areas to those
31
outside revealed that MPAs contained a higher number of species on average than non-
protected areas with 36.7 species in MPAs and 34.0 in areas outside.W
hite V
illa
Corsair
e Ree
f
Auberge
Ree
f Sit
e XW
hale R
ockRay
's Poin
t
Anse M
ajor R
eef
Anse M
ajor P
oint
Willi
e's B
ay R
eef
Willi
e's B
ay P
oint
Site Y
Baie Te
rnay
North
East
Secr
et B
each
Baie Te
rnay
Cen
tre
Baie Te
rnay
North
Wes
t
Baie Te
rnay
Ligh
thouse
Port La
unay So
uth R
eef
Port La
unay W
est R
ocks
Conception N
orth P
oint
Conception C
entra
l Eas
t Fac
e
Ther
ese N
orth En
d
Ther
ese N
orth Ea
st
Ther
ese S
outh05
101520253035404550
Survey Site
No
. of
surv
eye
d s
pe
cie
s p
rese
nt
Figure 4.10.1. Species-richness (number of fish species found) across all survey sites along NW Mahé, 2012. Green denotes
sites within Marine Protected Areas and blue denotes non-protected sites.
A comparison of species-richness between the same sites surveyed in 2005 and the results
from 2012 reveal a significant increase in the number of surveyed fish species present
across all areas (fig. 4.10.2.); with a mean increase of 6.63 species (± 1.35 SE) over all
sites. The only exception of this rise was Therese North End and Conception Central East
Face survey sites which both recorded a drop of 1 species.
White
Vill
a
Corsai
re R
eef
Site
X
Whal
e Rock
Anse M
ajor R
eef
Site
Y
Baie
Tern
ay N
orth E
ast
Baie
Tern
ay C
entr
e
Baie
Tern
ay N
orth W
est
Baie
Tern
ay Li
ghth
ouse
Port La
unay S
outh R
eef
Port La
unay W
est R
ocks
Conception N
orth P
oint
Conception C
entr
al E
ast F
ace
Ther
ese
North E
nd
Ther
ese
North E
ast
05
1015202530354045
2005
2012
Survey Site
No
. of
surv
eye
d s
pe
cie
s p
rese
nt
Figure 4.10.2. A comparison of species-richness (number of fish species) between the same sites of NW Mahé in 2005 and
in 2012.
32
1.8 Commercial Fish Sizing Results
All volunteers are assessed on their ability to estimate size of the commercial fish species
when sighted underwater. Assessment was carried out by use of on-land training, where
volunteers are asked to size objects from varying distances and instant feedback is given.
On-land testing is also given by sizing a line with artificial fish attached from a distance of
no closer than 2m. In-water assessment was carried out using a line with sections of
polyurethane piping of known length. Volunteers estimate the lengths underwater and
results and feedback are given after each dive. Along with practice methodology,
assessment is also undertaken within the fish survey practice methodology under the
supervision of a staff member. All volunteer’s sizings are checked against the staff’s
recording. Only when a volunteer displayed 100% accuracy in sizing fish to the 10cm
bandwidth on both in-water piping assessment and the practice surveys were they allowed
to conduct surveys. All volunteers from the past survey phase could accurately define the
size of all commercial fish species to within the 10cm bandwidth required.
33
1.9 Invertebrate Densities from 10m Transects
Specific surveyed invertebrate species have been increasing across all sites since surveys
began in 2005. Accelerated rates of increase have been observed since 2008 with the
exception of densities for the Platyhelminthes and black spined urchins of the Echinothrix
sp. and Diadema sp. which have remained relatively stable. The most significant of the
increases in densities are seen in the Arthropoda and Mollusca phyla. The Arthropoda
phyla has increased from low level densities found in 2005 of 0.01 individuals per m2 up to
one of the most abundant species with a current maxima of 1.53 individuals per m2 for
2012, the Mollusca phyla has shown a similar increase with time. In 2005 Mollusca
densities were found at 0.11 individuals per m2 and in 2012 density had increased to 1.54
individuals per m2 averaged across all sites. Echinodermata phyla has also been increasing
throughout the survey program however results from 2012 show a reduction in the
densities dropping from 1.64 individuals per m2 in 2011 to 1.50 individuals per m2 in 2012
(see figure 4.12.1).
Apr-Jun 05
Oct-Dec
05
Apr-Jun 06
Oct-Dec
06
Apr-Jun 07
Oct-Dec
07
Apr-Jun 08
Oct-Dec
08
Apr-Jun 09
Apr-Jun 10
Apr-Jun 11
Jan-Ju
n 120.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80AnnelidaPlatyhelminthesArthropodaMolluscaEchinodermataBlack Spined Sea Urchins
Survey Phases
Inve
rteb
rate
Den
sity
(ind
ivid
uals
/m2)
Figure 4.12.1. Mean density (individuals per m²) of invertebrate phyla and black spined sea urchins at carbonate reef sites,
for every survey period from 2005 to 2012
When the results are divided by substrate type the invertebrate densities show differences
between them. Granitic sites show a greater spread in the densities of the surveyed
invertebrates. The most significant increase is found in the mollusc phyla which has
increased from 0.17 individuals per m2 in 2005 to 2.38 individuals per m2 for 2012 and has
become the dominant invertebrate phyla on granitic sites. The Arthropoda phyla has also
34
continued its increasing trend seen in recent years. Echinodermata densities have dropped
since 2011 decreasing from 1.84 per m2 to 1.35 per m2 in 2012. (Figure 4.12.2).
Apr-Jun 0
5
Oct-Dec
05
Apr-Jun 0
6
Oct-Dec
06
Apr-Jun 0
7
Oct-Dec
07
Apr-Jun 0
8
Oct-Dec
08
Apr-Jun 0
9
Apr-Jun 1
0
Apr-Jun 1
1
Jan-Ju
n 12
0.0
0.5
1.0
1.5
2.0
2.5
3.0AnnelidaPlatyhelminthesArthropodaMolluscaEchinodermataBlack Spined Sea Urchins
Inve
rte
bra
te D
en
sity
(in
div
idia
ls/m
2)
Figure 4.12.2. Mean density (individuals per m²) of invertebrate phyla and black spined sea urchins at granitic reef sites, for
every survey period from 2005 to 2012.
Carbonate sites show a similar increase in density for most of the surveyed invertebrate
species. Arthropoda phyla have increased significantly over the monitoring program
however in 2012 the densities have stabilised. Densities of black spined urchins have
decreased over the past two year, however the Echinodermata phyla has continued to
increase showing that this increase in the other surveyed urchin species (Figure 4.12.3.).
Apr-Jun 05
Oct-Dec
05
Apr-Jun 06
Oct-Dec
06
Apr-Jun 07
Oct-Dec
07
Apr-Jun 08
Oct-Dec
08
Apr-Jun 09
Apr-Jun 10
Apr-Jun 11
Jan-Ju
n 120.0
0.5
1.0
1.5
2.0
2.5AnnelidaPlatyhelminthesArthropodaMolluscaEchinodermataBlack Spined Sea Urchins
Inve
rteb
rate
Den
sity
(ind
ivid
ials
/m2)
Figure 4.12.3. Mean density (individuals per m²) of invertebrate phyla and black spined sea urchins at carbonate reef sites,
for every survey period from 2005 to 2012.
35
1.10 Invertebrate Densities from 50m Belts
In total 46 invertebrate abundance belts were completed across all the 23 sites surveyed,
covering a total area of 11,500m2. The trends in density levels found during 2012 continue
those found with all previous survey phases. Short-spine (Echinothrix sp.) at 0.31 per m2
SE ±0.05 and long-spine (Diadema sp.) at 0.15 per m2 SE ±0.08 (fig. 4.13.1.) still show the
highest abundance of all the surveyed invertebrates; significantly higher than all other
invertebrate species found with the exception of Drupella snails.
Short
Spin
e Urc
hin
Long S
pine U
rchin
Pencil
Urc
hin
Flower
Urc
hin
Mat
hae’s
Urchin
Cake U
rchin
Other
urc
hins
Cushio
n seas
tar
Crown o
f Thorn
s
Other
seas
tars
Drupell
a
Giant C
lams0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Invertebrate Species
Me
an d
en
sity
pe
r m
2
Figure 4.13.1. Mean density per m2 of all surveyed invertebrate species across north-west Mahé, 2012.
When dividing the two most abundant invertebrates by substrate type some interesting
trends can be observed (figure 4.13.2.). Short-spine sea urchins show a preference to
granitic substrate, indicated by the higher density levels on these reefs; whereas long-spine
sea urchins display similar density levels over both substrates; not indicating any
preference. Up until 2011 there has been a general increasing trend for these two species
groups, with the exception of short spine urchins on carbonate reefs displaying stable
density throughout. However monitoring through 2011 - 2012 shows a decrease in the
abundance of long spine urchins on both carbonate and granitic sites. Short spine urchins
have remained relatively stable on both substrates.
36
Jan-M
ar09
Jul-S
ep09
Oct-Dec
09
Jan-M
ar10
Jul-S
ept1
0
Oct-Dec
10
Jan-M
ar 11
Jul-S
ept 1
1
Oct-Dec
11
Jan-Ju
n 120.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70Long Spine CarbonateLong Spine Granitic Short Spine CarbonateShort Spine Granitic
Survey Phases
Mea
n D
ensi
ty p
er m
2
Figure 4.13.2. A comparison of the mean density per m2 of short spine (Echinothrix spp.) and long spine (Diadema spp.)
urchins on granitic versus carbonate substrate along north-west Mahé, Jan - Mar 2009 to 2012.
Studies of the trends in the corallivorous invertebrates show significant, almost alarming,
increases in abundances across the survey sites. Figure 4.13.3. shows the density levels of
the major corallivorous invertebrates of Crown of Thorns seastar (Acanthaster planci),
Cushion Starfish (Culcita spp.) and Drupella snails.
Jan-M
ar09
Jul-S
ept0
9
Oct-Dec
09
Jan-M
ar10
Jul-S
ept1
0
Oct-Dec
10
Jan-M
ar 1
1
Jul-S
ept 1
1
Oct-Dec
11
Jan-Ju
n120
0.02
0.04
0.06
0.08
0.1
0.12
Cushion seastarCrown of Thorns seastarDrupella
Survey Phase
Me
an d
en
sity
pe
r m
2
Figure 4.13.3. Mean density per m2 of Cushion Seastar (Culcita spp.), Crown of Thorns (Acanthaster planci) and the
gastropods Drupella spp.
Density levels of both the Crown of Thorns Seastar (Acanthaster planci) and the Cushion
Seastar (Culcita sp.) have remained at very low and stable densities. The density of
Drupella snails however have been increasing significantly since early 2010; reaching its
maximum for 2012 of 0.11 per m2.
37
1.11 Sea Cucumber Densities
The total number of sea cucumbers found across all survey sites of north-west Mahé was
336 individuals for 2012. Figure 4.14.1 shows the total number of sea cucumbers found per
site averaged for each year of survey. This graph clearly displays after the initial rapid
decrease in abundance of sea cucumbers seen in 2007 the populations are increasing
across all the survey sites
2006 2007 2008 2009 2010 2011 20120.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
Me
an
nu
mb
er o
f C
uc
um
be
rs f
ou
nd
pe
r s
ite
su
rv
ey
ed
Figure 4.14.1. Mean Number of sea cucumbers recorded per site from 2006 -2012
Analysis of individual sea cucumber species reveals that both Pearsonothurian graeffei and
Stichopus spp. remain the most abundant sea cucumbers across all sites with both finding
densities of 0.011 (fig. 4.14.2.). Interestingly, P. graeffei numbers have rebounded rapidly
in 2012, this resurgence was seen across many sites with high abundances found relative
to recent years of surveying. High abundances of these two species is significant as they
are of little commercial value, compared to the other surveyed sea cucumbers which show
lower abundance levels.
Oct-Dec
08
Jan-M
ar 0
9
Jul-S
ep 0
9
Oct-Dec
09
Jan-M
ar 1
0
Apr-Jun 1
0
Jul-S
ep 1
0
Oct-Dec
10
Jan -
Mar
11
Apr - Ju
n 11
Jul-S
ep 1
1
Oct-Dec
11
Jan-Ju
n 120
0.002
0.004
0.006
0.008
0.01
0.012
0.014Holothuria atra
*Holothuria fuscopunctata
*Holothuria fuscogilva
*Holothuria nobilis
*Holothuria sp. (Pen-tard)
Bohadschia sp.
Actinopyga sp.
*Actinopyga mauuri-tiana
Stichopus sp.
*Thelenota ananas
Pearsonothurian graeffei
Holothuria edulis
Thelenota anax
De
nsi
ty p
er
m2
Figure 4.14.2. Density per m2 of individual sea cucumber species across all survey sites of north-west Mahé, Oct - Dec 2008
to Jan - Jun 2012.
38
5. Discussion
1.12 Coral Surveys
Overall mean coral coverage has increased significantly over the past seven years of reef
monitoring conducted by GVI across North West Mahé. Mean percentage coral coverage
has increased from 10.25% ± 1.27 SE in 2005 up to 36.42% ± 1.78 SE in 2012. Currently
both granitic and carbonate reefs have reached a maxima for coral cover since surveys
began; granitic reefs with 38.10% coral cover and carbonate at 34.74%. However, since
2010 the rate of coral growth seems to have slowed; coral cover only increased by 1.99%
between 2010 and 2012, a significantly lower rate than the 8.16% increase between 2008
and 2010. Yet, overall any increase in cover is encouraging for the continued regeneration
of the reefs after the mass coral bleaching event in 1998.
When analysing the results by substrate type this year’s results display a similar increase in
coral cover on both granitic and carbonate reefs at a mean of 1.7%. For carbonate sites
this is a similar change to that which was seen between 2010 - 2011, however for granitic
sites it shows an increase this year compared to a drop in coral cover seen between 2010 -
2011. Granitic reefs maintain the higher coral coverage in results from 2012, a trend which
has been seen since surveys began. Engelhardt (2004) attributes the elevated coral cover
at granitic sites to higher water clarity linked to their position. Granitic sites are found at
more exposed points with high water flow, whereas many carbonate sites are within
sheltered bays receiving lower water flow rates resulting in higher nutrient and sediment
levels through run off from terrestrial sources. The lower flow rates found in these sheltered
bays means these high nutrient and sediment levels persist which can negatively affect
coral growth (Nugues & Roberts 2003; Ferrier-Page`s et al. 2000; Ward & Harrison 2000).
This hypothesis is also represented in the site specific information; the two sites displaying
highest coral cover are Site X (49.73%) and Port Launay West Rocks (49.53%) both of
which are exposed granitic sites. However, Baie Ternay Centre exhibited high coral
coverage at 49.18% despite being a relatively sheltered carbonate reef. Baie Ternay
Centre is located within the Baie Ternay Marine Park and benefits from the protection from
fishing, which creates a more natural state ecosystem and increases reef resilience to
stresses (Belwood et al. 2004; Graham et al. 2006; Mumby 2006). Most of the other carbonate
sites with lower percentage coral cover do not benefit from the protection from fishing found
within the Marine Parks. Overall percentage coral cover within the Marine Parks of both
Baie Ternay and Port Launay show higher coral cover. Inside the Marine Parks average
39
percentage coral cover was 40.10% whereas outside these protected areas was 35.25%
attesting to the importance of overall ecosystem health for resilience of the corals species.
Continual benthic coverage is recorded for all line intersect transects, results averaged over
all sites for 2012 found 49.54% of coverage was algae compared to 36.57% for coral cover.
This shows algal dominance across all sites for 2012; however analysing the coverage of
algal species shows that 92.3% of the algae recorded was turf algae; this diminutive,
filamentous algal is associated with relatively pristine, healthy reef systems and is a major
contributor to high algal productivity (Steneck 1988; Klumpp & McKinnon 1989). While it is well
established that macroalgae can outcompete and overgrow corals (Birkeland 1977; Hughes
1994; Jompa & McCook 2002a, 2002b) results from 2012 found these species to compose just
0.2% of total algal coverage.
Analysis of the other algae and epibenthic organisms, with the exception of Scleractinian
corals, shows low coverage of below 12.0% on both granitic and carbonate reefs. The
carbonate reefs shows a larger range in the densities of these other organisms however
the relative dominance has remained stable, with corallimorphs / zooanthids and soft coral
achieving highest densities on this substrate, notable as they compete rigorously with
scleractinian coral for space (Lindèn et al. 2002); although densities are still much lower than
that of the coral. Granitic sites show lower coverage of all algae and epibenthic organisms.
The most dramatic trend on this substrate is the decrease in coralline algae seen since
2005. High coverage of coralline algae indicates consolidation of reef structure (Grimsditch
et al. 2006). This reduction could slow the consolidation of loose rubble on the surface of the
reef which would damage adult coral colonies, but would have a more dramatic affect on
the coral recruitment rates; as the abrasion of the loose rubble can damage and remove
newly settled recruit corals (Turner et al. 2002). Coralline algae on carbonate reefs seem to
be at a relatively stable coverage.
Analysis of the structural complexity of the reefs of the Seychelles is showing very positive
recovery post the 1998 bleaching event. Structural complexity of the reefs is important for
the overall health and diversity of the reef ecosystem, a complex reef structure allows for
extensive habitat space for other organisms such as fish and invertebrate species to
flourish (Garpe et al. 2006; Glynn 2006; Graham et al. 2006). Branching coral lifeforms have the
effect of increasing the physical matrix of the reef by increasing its structural complexity.
Acropora and Pocillopora species predominantly display the branching lifeforms (Veron
2000) these fast growing species are hardest hit by coral bleaching events (McClanahan et
al. 2004), but also fastest to recover. Previous coral surveys from Seychelles post 1998
40
found very low coverage of the coral species Acropora and Pocillopora. Whereas the
massive species, those that are more resilient to coral bleaching, such as Porites and
Goniopora dominated the coverage (Engelhardt et al. 2003). Figure 4.4.2 shows the trends in
the recovery of the reef after the initial surveys completed by Engelhardt et al. 2003. The
results show a significant increase in branching corals from 2005 - 2012 currently making
up 43.03% of the coral surveyed; a maximum since surveys began. Branching corals have
now become the dominant coral lifeform, rising above coverage of encrusting corals. Sub-
massive corals also show an increase in coverage across all reefs since 2005; however the
rate is much slower. The continued growth of both these lifeforms is a positive sign of
continued reef recovery and increasing structural complexity, which has the potential to
support a greater abundance and diversity of reef organisms. Surveys have also shown
decreases in percentage coverage of both encrusting and massive corals from 2007
onwards; this could be due to the faster growing, branching species, outcompeting these
corals for space on the reef.
Differences in the structural complexity of the two substrate types is also evident.
Carbonate reefs currently maintain a very high percentage of branching corals; making up
52.02% of corals found. Granitic sites have been continuously dominated by encrusting
corals which contribute little to structural complexity of the reefs, however the granitic sites
have inherent complexity from granitic boulders located across the sites; this is a common
feature of all the granitic sites that are surveyed. On granitic sites the coverage of
encrusting corals has been slowly decreasing as the branching corals increase and if these
trends persist within the next few years branching corals will dominant both granitic and
carbonate reef substrate. A positive sign in terms of structural complexity.
The diversity of coral on the surveyed reefs has increased through the monitoring program.
Initially a rapid increase in the mean diversity was seen up until 2007, then stabilised from
this point at a mean diversity of around 31 genera per site. Diversity divided by carbonate
and granitic reefs has always been similar and the results from 2012 are no exception,
finding an average of 31 genera on both the substrate types. It is interesting to note that
although the number of different genera found overall seems to have stabilised, the spread
of coral genera found at every site is increasing. Through analysing the number of coral
genera found at every site; in 2005 only four coral genera were found at each, however in
2012 19 coral genera were found at every single site; a new maxima for the monitoring
program. Indicating that although overall diversity has remained relatively stable the corals
already established on some of the reefs are settling further into new areas.
41
1.13 Fish Surveys
The fish section of this report contains results from surveys conducted between January to
June 2012, recording the abundance and diversity of both reef and commercial fish
species. The true value of this data is in the contribution it makes to the larger data set
comprising results from the last 11 years; the insights this provides on the status of coral
reefs in the Seychelles inner-islands; and subsequently on the status of coral reef
knowledge around the world.
It is not possible to analyse specifically the causes of any density fluctuations which occur
from one survey period to the next, and false, redundant conclusions would be made
without further specific studies into each. However, the wealth of information that the data
provides in terms of viewing the long-term phase shifts after mass coral reef mortality are
invaluable, and comparisons can be made between the results discovered in Seychelles to
other reef studies about the world.
One approach to viewing the relative health of survey sites is to compare the species-
richness, or diversity, of the areas both to one another and over time. High species-
richness indicates a reef, which can support the needs of varying species and an
associated complex food web. Many studies have highlighted the positive correlation of
species-richness of both fish and other targeted organisms to the structural complexity of
the reef substrata of a site (Chabanet et al. 1996; Luckhurst & Luckhurst 1978; Talbot et al. 1978;
Roberts & Ormond 1987).
Arguably, the greatest impact on Seychelles’ fish populations after the coral bleaching in
1998 was in species-richness (Graham et al. 2006). The immediate loss of live coral cover
and physical structure of the reef (fig. 4.4.1.) eliminated resources for fish; both physical
habitats and prey. With the lack of resources, the ability to provide for a range of species
was diminished and the diversity of all sites declined dramatically. In viewing the change of
coral lifeforms since 1998, (fig. 4.4.2.), it can be seen that the reefs have increased from
only massive and encrusting lifeforms remaining to a much higher percentage of branching.
Comparing current diversity results at all sites to initial diversity recording in 2005 has
shown an average improvement across all sites of +6.63 species, with the exception of only
two sites (fig. 4.10.2.). The diversity results also revealed that Marine Protected Areas
(MPAs) harboured a higher number of targeted survey species, with an average of 36.7
species inside protected areas compared to 34.0 outside.
42
When viewing fish densities along north-west Mahé it is necessary to divide the results into
protected and unprotected areas. MPAs within Seychelles are designated zones where the
removal of any species is illegal and the anchoring of boats and level of tourism is
monitored. These no-take zones have been developed to serve as both safe-houses for
targeted fish species and coral reefs, but also so that they may potentially benefit fish
stocks through the theory of ‘spillover’, the net export of adult fish, from an area of high
density to adjacent non-protected areas of lower fish density (Abesamis & Russ 2005).
The results show that MPAs do harbour a higher mean density of fish per m2, with an
average of 0.359 fish per m² found within the MPAs compared to 0.306 per m² outside.
Both carbonate and granitic substrate sites held higher densities levels inside protected
zones, although granitic sites constantly fluctuate between dominance. It is also interesting
to note that sites immediately adjacent to MPAs, such as Baie Ternay Lighthouse and Site
Y also have comparatively high numbers of fish.
Despite clearly holding healthier abundance levels of fish, it is difficult to measure the
effectiveness of MPAs due to many reasons, and multiple studies have attempted to do so
(Field et al. 2006). It is also difficult to control for the selectiveness of MPAs. Most MPAs are
chosen for their higher densities and species-richness of fish and other organisms, as well
as their potential for recruitment and juvenile species’ habitat. It is reasonable, then, that in
studying the densities of fish within and outside of the protected areas that the MPA would
hold a higher number than non-protected areas as it originally did so. In analysing the data
of both fish densities and coral health since 1998, however, MPAs clearly recovered faster
than non-protected areas and have achieved higher density levels overall.
It is undeniable that as management tools, MPAs potentially offer a form of insurance
against overexploitation of target species and a reduction in undesirable fishing induced
impacts on non-target species and fishing-induced impacts to habitat (NRC 2001; Gerber et
al. 2003; Halpern 2003). The continued protection of these areas is paramount to maintaining
healthy fish populations.
Separating the fish results into feeding guilds, a system based on the prey preference of
individual species, allows for a clearer viewing of the internal trends of fish population
dynamics across the years. Most notably the herbivore class have been the most dominant
43
in density across all sites and have had a stable density level irrespective of the years (fig.
4.8.1.).
Herbivores are key components to the coral reef ecosystem; mediating competition
between benthic algae and scleractinian corals (Miller 1998). Their pressure on the growth
of algae allows corals to flourish in areas where competition for resources and overgrowth
is minimised and substrate is freed for recruitment (Sluka & Miller 2001). Theoretically, the
impact of the 1998 bleaching event in Seychelles would have had a minimal effect on the
density levels of herbivores and the density results found across the years reflect this (fig.
4.8.1.). Having very little or no direct reliance on scleractinian coral itself, the dramatic
decrease in coral coverage would not have had the same impacts on resource availability
for herbivores. In fact, the decrease in coral coverage had a reverse effect on algal growth,
with the algae coverage at an all-time high in the years directly following the bleaching. The
stable populations of herbivores on the reefs kept this bloom in check, allowing the slow
regrowth of coral. Macroalgae, or more specifically seaweed, if not removed by herbivores
would be the most competitively dominant organism on a coral reef and would be capable
of destroying reefs as we know them (Hughes 1994). Research conducted on the Great
Barrier Reef immediately following the 1998 bleaching event also solidified the importance
of herbivory; with experimental manipulations removing herbivores from degraded areas
causing a dramatic explosion in macroalgae which in turn suppressed the fecundity,
recruitment, and survival of corals (Hughes et al. 2007).
As the second most dominant feeding guild the planktivores have shown a steady decline
in numbers across survey years (fig. 4.8.1.). As their prey comes solely from the water
column above the reef, planktivores are not sensitive to the phase shifts in the coral
beneath them (Sluka & Miller 2001) and were unaffected by the initial degradation of the
reefs post the 1998 bleaching. This decline in numbers in recent years is therefore due to
influences outside of the coral reef ecosystem. High density levels of planktivores can
indicate areas of upwelling and nutrient-rich water; however between the months of
January to June Seychelles water clarity is at its highest. This clear water has low levels of
plankton, seen both through the turbidity measurements of each survey and the lessened
plankton densities in the sample tows conducted each week. If this hypothesis of
planktivore density linked to visibility is correct, densities will rise in the following six months
of the year as the south-westerly monsoon brings upwellings of plankton to the north-west
coast of Mahé. In addition, it is also difficult to accurately survey the planktivores
specifically, as many are nocturnal species (primarily the Holocentridae family; soldierfish
44
and squirrelfish) and during the day reside in the dark areas of the reef. When visibility, and
therefore light penetration through the water column, is at its highest, Holocentrids retreat
further into the crevices.
Another key trend emerging from the long-term data set is the steady increase in the
corallivore feeding guild. Obligate corallivores rely solely on the live tissue of corals for their
food and their energetic demand is intimately linked to the health of the coral ecosystem
(Jones & McCormick 2002); if corals are adversely affected by stressful conditions their health
will deteriorate and this deterioration will be mirrored by the fish that feed on them (Crosby &
Reese 1996; Pratchett et al. 2004). This strong linkage has led to many corallivore species
being used as ‘indicator species’ in different coral ecosystems about the world, allowing
researchers to gather a picture of the health of a reef area by only recording the distribution
and specific abundance of corallivorous species.
The data since 1998 shows a steady rise in the corallivore guild from the initial density
recordings of 0.001 to 0.036 fish per m². This rise has mainly been due to the increase in
two butterflyfish species; Chaetodon trifascialis (Chevroned) and Chaetodon trifasciatus
(Indian Redfin). When overlaid with the rise in percentage hard coral cover through the
survey years (fig. 4.2.1.), corallivore density perfectly mirrors that of coral coverage. In
addition to this, studies directly after 1998 alerted that four Chaetodontid species, C.
meyersi, C. trifascialis, C. lineolatus and C. melannotus, were possibly locally extinct or in
critically low abundance on Seychelles coastal reefs (Graham et al. 2006). Three of these
four species are now in healthy density levels along many of the surveyed sites, with only
C. lineolatus at a low level.
All Chaetodontids are corallivorous, however many species also predate upon
invertebrates, algae and other benthic organisms and so are not as intrinsically linked to
the health of scleractinian coral and are able to adapt their diet somewhat to feed on prey in
proportion to their abundance (Crosby & Reese 1996). This aside, a similar increase in the
corallivore/ invertivore guild can be seen (fig. 4.8.2.) and the same assumptions of
associations between abundance of species and health of coral can also be made for this
guild.
Consequently, all results combine highlight the need for thorough management of both fish
stocks and of coral reef areas to provide some insurance against larger-scale disturbances,
such as the 1998 event, which are impractical to manage directly.
45
1.14 Invertebrate Surveys
Invertebrates have been studied as biological indicators within terrestrial and aquatic
ecosystems extensively, including coral reef habitats. Their importance lies in their
interactions with the reef habitat, and density may reflect changes in reef composition and
structure. Densities of surveyed invertebrates from the 10m belt transects have been
increasing since surveys began with the exception of black spine urchins and
Platyhelminthes. Platyhelminthes show low densities due to their lifestyle; these species
are generally nocturnal and found mostly under the rock and rubble of the reef (Coleman
2000), but are also hard to spot as most species are small and camouflaged.
The overall increases in all surveyed species indicate that the diversity of the reefs is
continuing to grow; following an increase in coral coverage. One of the most significant
increases seen is within the Arthropoda and Mollusca phylum. Increases in the Arthropoda
phylum can be linked to the build-up of structural complexity. The main families within the
Arthropoda phylum are the coral crabs and hermit crabs, the increases in branching corals
allow for more habitat space for the coral crab to flourish, the hermit crabs which make up
the other bulk of the Arthropods, show a continual increase with the mollusc families which
provide the crabs with the shell used for refuge.
Mollusca density increases was largely due to the vast oyster abundance recorded, mainly
of the species Hyotissa hyotis. These bivalves attach to rocks or coral on reef faces and
walls, which corresponds to the high abundance within granitic sites. The driver behind the
increase in oyster abundance is unclear. Density of Annelids has been increasing slowly
since 2005; high abundance of this phylum can be an indicator of water quality as they filter
feed organic matter in the water column. The overall lower densities seen are perhaps an
indicator of clear water with a low food source, which isn’t able to support high populations.
The increasing trend seen is probably linked to the increasing coverage of massive corals
across the reefs. The two main genera of Annelids found during the survey are the
Sabellidae sp. and Serulidae sp. which are coral borers and prefer the massive corals such
as Porites (Coleman 2000). It is more likely that the increase in density seen is due to the
availability of habitat rather than deterioration in water quality.
Echinodermata have different functions on the reef; the Echinoidea influence algal cover,
two species of Asteroidea are coral predators whereas Crinoidae feed on plankton species
in the water column and Ophiuroidea feed on a variety of prey. Increased numbers within
46
this phylum on both granitic and carbonate reefs indicates towards the continued recovery
of the reefs. As the Echinoderms feed on a variety of prey the overall ecosystem must be
stable to be able to support this diverse group.
The survey list for invertebrates on the 50m belts focuses on commercially important
invertebrates and key species which indicate ecosystem change. Results from 2012 show
continuation in trends seen in recent years with regards to the Echinoidea phyla. The most
dramatic change is within the corallivorous species, Drupella snails, where density levels
have increased significantly since 2010 reaching a new maximum this year. The most likely
explanation for the increase in the Drupella numbers is that it is coupled with the increase
in the branching coral Acropora spp., their preferred food source and habitat. Although
densities have increased, overall it is still quite low with only 0.11 Drupella per m². With
continued monitoring it will indicate whether this population is increasing to damaging
levels.
47
6. Additional Ecosystem Monitoring
6.1. Turtles
Five species of marine turtles are found in the Seychelles EEZ waters: the leatherback
(Dermochelys coriacea), loggerhead (Caretta caretta), olive ridley (Lepidochelys olivacea),
hawksbill (Eretmochelys imbricata), and green (Chelonia mydas) (IUCN 1996). The
leatherback, loggerhead and olive ridley, although common to parts of the Western Indian
Ocean, are not thought to currently nest in the Seychelles and are rarely seen. In contrast,
the hawksbill and green are residents in coastal waters of the Seychelles, nest on the
beaches, and are commonly observed. All five species found in the Seychelles face the
combined threats of poaching, pollution and loss of nesting sites, and are listed by IUCN as
endangered or critically endangered. The Seychelles is considered one of the most
important sites for the critically endangered hawksbill turtle and is one of the only localities
in the world where they can be observed nesting during daylight hours.
GVI staff and volunteers are trained in turtle biology and the identification of the two
species commonly seen around north-west Mahé, C. mydas and E. Imbricata, through
lectures and PowerPoint presentations. Volunteers are also trained in survey methodology
for water based and land based turtle surveys.
6.1.1. Incidental Turtle Sightings
For every dive undertaken by GVI, a record of turtle observations is kept. The parameters
for each of GVI’s dives are logged, regardless of whether or not a turtle was seen, enabling
the calculation of turtle frequency per dive and thus effort-related abundance. The species,
carapace length, sex, distinguishing features and behaviour of all turtles sighted is recorded
wherever possible.
Incidental sightings of sea turtles are divided into three month periods to more accurately
view the fluctuations that occur in and outside of nesting season. Within the January to
March time period of this report phase, a total of 111 turtles were sighted on 164 boat
outings whereby dives were completed in that period (discounting dives that were
specifically looking for turtles as part of the focal behaviour study). 72 of these sightings
were identified as hawksbill turtles and 39 as green turtles, with an overall sighting
frequency for all dives of 67.7%. Within the April to June period following this, only 57
48
turtles were sighted on 149 dives; consisting of 40 hawksbills and 17 green turtles, giving a
much lower overall sightings frequency of only 38.3% (Fig. 6.1.1).
In analysing the sightings results, the frequency found within January to March is
comparatively high; agreeing with the similar findings from October to December 2011. This
shows a remaining stationary population of turtles within the bay in this time. Green turtle
sightings were also particularly high for this period, mainly due to continuous sightings of a
number of resident immature turtles within Baie Ternay Marine Park, known individually
from photo-identification and carapace characteristics.
The results from the April to June period, however, were significantly lower. Within a
relatively short time period of 2-3 weeks during May sightings of both green and hawksbill
turtles declined rapidly. It is unknown what caused this immediate departure from the area.
It is known, however, that October to January is the typically the time at which turtle
encounters increase within certain Seychelles' coastal waters due to an immigration of
sexually mature turtles to these designated nesting areas, and hence the months outside of
the time have lessened sightings of turtles. Previous studies on the nesting turtles of
Cousin and Silhouette Islands, Seychelles, have shown that adult turtles rarely reside in the
area in which they nest on a year round basis; undertaking short migrations to other
habitats along the Mahé plateau in the off-season months of April through September
(Witzell 1983; Houghton 2003; Ellis & Balazs 1998). Findings from other studies in the
Seychelles area also indicate that smaller turtles within the sub-adult category (35 - 80cm)
generally reside in coastal coral reef habitats year-round; regardless of nesting season
(Witzell 1983; Houghton 2003; Ellis & Balazs 1998).
To further understand the ecology of turtles within Northwest Mahé, the curved carapace
length (CCL) of any turtle sighted is also estimated. Carapace length can be used as a
guide to the stage of sexual maturity of sea turtles. The approximate minimum carapace
length of breeding-age female green and hawksbill turtles is 105cm and 80cm respectively
(Mrosovsky 1983). The mean estimated carapace length for hawksbill turtles during the
January to March and April to June period was 50.1cm (± 1.2 SE) and 52.4cm (± 2.4 SE)
respectively (fig. 6.1.2.). This reveals a steady population of sexually immature sea turtles.
Turtles within this life stage are known to recruit to coastal developmental habitats for some
months, and not to migrate during the nesting season. It is therefore unlikely that migration
is key to this sudden departure of turtles during April. One hypothesis may be that the
migration of adult turtles to the nesting beaches elsewhere in Seychelles increases
competition in those coastal waters, and hence the immature turtles are forced to move
49
elsewhere, collecting in the North of Mahé where nesting turtles do not and increasing
sightings numbers.
It also may be that the seasonal changes that occur around the month of May influence the
change in turtle sightings frequency; including a drop in sea temperature from 29-30˚ C to
25-27˚ C. Without additional studies it is impossible to determine whether environmental
parameters have any effect upon sea turtle recruitment to coastal areas.
In breaking down the data to specific dive sites it is important to note that most, or rather
almost all, turtle sightings were within the confines of Baie Ternay Marine National Park;
specifically towards the centre and northwest areas. Furthermore, in the January to March
period, sightings of more than one turtle on each dive often occurred in these areas, with
the maximum number of turtles sighted within a single dive being three.
Oct
-Dec
05
Jan-
Mar
06
Apr
-Jun
06
Jul-S
ep 0
6O
ct-D
ec 0
6Ja
n-M
ar 0
7A
pr-J
un 0
7Ju
l-Sep
07
Oct
-Dec
07
Jan-
Mar
08
Apr
-Jun
08
Jul-S
ep 0
8O
ct-D
ec 0
8Ja
n-M
ar 0
9A
pr-J
un 0
9Ju
l-Sep
09
Oct
-Dec
09
Jan-
Mar
10
Apr
-Jun
10
Jul-S
ep 1
0O
ct-D
ec 1
0Ja
n-M
ar 1
1A
pr-J
un 1
1Ju
l- Se
p 11
Oct
- D
ec 1
1Ja
n - M
ar 1
2A
pr -
Jun
120
10
20
30
40
50
60
Hawksbill Turtles
Green Turtles
Survey Phase
Fre
qu
en
cy o
f Si
ghti
ng
(%)
Figure 6.1.1. Frequency (%) of hawksbill and green turtle sightings around north-west Mahé from Oct- Dec 2005 to Apr- Jun
2012.
Apr
-Jun
06
Jul-S
ept 0
6O
ct-D
ec 0
6Ja
n-M
ar 0
7A
pr-J
un 0
7Ju
l-Sep
t 07
Oct
-Dec
07
Jan-
Mar
08
Apr
-Jun
08
Jul-S
ept 0
8O
ct-D
ec 0
8Ja
n-M
ar 0
9A
pr-J
un 0
9Ju
l-Sep
t 09
Oct
-Dec
09
Jan-
Mar
10
Apr
- Ju
n 10
Ju
l - S
ep 1
0O
ct -
Dec
10
Jan
- Mar
11
Apr
- Ju
n 11
Jul -
Sep
11
Oct
- D
ec 1
1
Jan
- Mar
12
Apr
- Ju
n 120
10
20
30
40
50
60
70
80
Survey Phase
Me
an
cara
pace
le
ngth
(cm
)
Figure 6.1.2. Mean carapace length of hawksbill turtles around north-west Mahé from Jan- Mar 2006 to Apr- Jun 2012.
50
6.1.2. Beach Patrols for Nesting Turtles
Beach patrols are conducted on north-west Mahé during the Hawksbill turtle nesting
season from October to March. This land-based turtle monitoring work includes beach
walks, documentation of nesting tracks, and investigation of newly hatched clutches. Beach
patrols are carried out weekly at beaches local to the Cap Ternay research station (Anse
du Riz and Anse Major) to monitor nesting turtle activity. The surveys are conducted on
foot, with the teams searching for signs of tracks or body pits walking along the upper
beach, on the main beach, and also within the coastal vegetation.
Within the January to March period beach patrols on both Anse du Riz and Anse Major
beaches were conducted on 8 occasions. No evidence of tracks, nesting or of hatched
nests were found during this time. Two hawksbill hatchlings were sighted in the shallows of
Baie Ternay beach, however the strong sea currents and waves at that time suggested the
hatchlings were blown into Baie Ternay by stormy weather and did not come from a local
nest.
6.1.3. In-water Surveys of Turtle Behaviour
In studies concentrating on the home ranges of sea turtles it has been found that normal
daily activities of sea turtles centre around areas of high food availability and resource
quality. When sufficient resources are available, individuals develop affinities for specific
areas (Makowski et al. 2006). Preliminary results from research conducted by Von Brandis in
the Amirantes, Seychelles, established that philopatric behaviour is common among
foraging hawksbill turtles, and extensive information on individuals and their energy
budgets can be gathered using relatively non-invasive sampling protocols (Von Brandis pers.
comm.). Focal behavioural studies work on the philosophy that an individual, when followed
and observed correctly, can provide a wealth of ecological information that would otherwise
be unnoticed in a simple point count survey.
Our objective is to document important interactions between hawksbill turtles and their
environment while obtaining information of prey preference and the number of individuals
displaying philopatric behaviour within the Baie Ternay Marine Reserve. Volunteers use
SCUBA equipment to undertake a U-shaped search pattern. Divers look for focal animals
and, upon finding an individual, follow and document all behaviours observed.
Environmental conditions can dictate at what distance accurate observations are made
51
without altering normal behaviour but in general a distance of no closer than 5m is
sufficient. A continuous time scale of data is used; divers stay with any individual
encountered for as long as possible even if another individual is located. In the event that
another turtle is found, the second member of the buddy pair may start to document
behaviour but at no time are buddy pairs to become separated by more than 2m. Any
characteristic markings should be documented and the use of underwater photography is
highly desirable for turtle identification and determining unknown prey items. Due to
logistical constraints, it is only possible for the study in Baie Ternay to be carried out on a
weekly basis, incorporating two 45 minute dives with most volunteers participating in one
dive; however it is an interesting addition to the routine for volunteers, enhancing their skill
set and appreciation for marine ecological fieldwork.
Between January and June of 2012, two turtle behavioural dives were conducted each
week; wherein a combined total of 51 turtle sightings over 40 separate dives. These
sightings comprised 40 hawksbill, 10 green turtle and one ‘unknown’ sighting. The
estimated mean carapace length (CCL) of all turtles sighted was 59.31cm ± 2.09 SD. The
range of sizes of turtles varied from 35cm to 120cm, and most were accurately identified
through photo-identification and individual characteristics as being residential turtles of Baie
Ternay Marine Park.
Of these turtles sighted in the previous phase, again the greatest frequency of sightings
occurred within the 0-10m depth class, with only two sightings recorded outside of these
depths at 14m and 11m. The shallow reef slope of Baie Ternay Centre does bias the
results towards the shallower depth class, as the 0-10m range covers a larger area of reef
and therefore a larger area of foraging grounds. From the studies, it was noted that algae,
hard coral and soft coral were all common chosen food items.
Through the use of photo identification methods, spoken about in the following section, a
number of individual turtles have been seen returning to, or residing within, specific areas
of Baie Ternay marine park over a long time scale.
It is impossible to correctly determine the specific home range of sea turtles without the use
of remote telemetry, however one or more areas of disproportionately heavy use (i.e. core
areas) can be identified for some of the more frequently spotted turtles. Understanding the
spatial use patterns of sea turtles is fundamental to their conservation. This study reveals
that Baie Ternay remains an important habitat for both the endangered green and hawksbill
52
turtles; thus, further underscoring the need to develop and maintain conservation strategies
that address the impacts that threaten this region.
6.1.4. Photo Identification of Turtles
Throughout 2011 the use of photo identification methods for turtles was implemented into
all dives where volunteers or staff had an underwater camera. The post-ocular area of
scales on the left and right cheeks of both hawksbill and green turtles are unique to each
individual, allowing for comparisons to be made between identification shots taken on
different dives. Individuals can be recognised through analysis of the photographs, based
on a code defined from the localisation and the number of sides of each scale of the head
profile. This method has been taken from the Kelonia Observatory for Sea Turtles in
Reunion Island (Ciccione et al. n.d.).
The ability to recognise individuals in a population allows for reliable information to be
collected on distribution, habitat use, or life history traits. It is from the increased emphasis
on the importance of photographic identification that resident turtles have been accurately
re-identified, and their home ranges consequently estimated within Baie Ternay marine
national park. A number of individual turtles, both hawksbill and greens, have been
accurately re-identified over varying time scales within the MPA. From data collected from
these sightings it has been noted that many have distinct habitat preferences and feeding
and resting areas. Photo-identification has also been critical in identifying the reasons
behind the low trend in carapace length and any incidence of philopatric behaviour.
53
6.2. Crown of Thorns
Outbreaks of the coral predator, the Crown of Thorns starfish (Acanthaster planci), were
first reported in 1996 and were active until 1998, when the reefs suffered from the
bleaching-induced coral mortality (Engelhardt 2004). Normal density levels are less than one
individual per hectare (Pratchett 2007) and in these numbers A. planci can assist coral
diversity by feeding on the faster growing corals such as Acropora and Pocillopora, which
are its preferred prey items (Pratchett 2007) and early colonisers of degraded reefs that can
out-compete slower growing corals (Veron 2000). In high numbers however the level of
competition for food drives the starfish to eat all species of corals and reefs can become
severely degraded with coral cover reduced to as little as 1% (CRC Reef 2001). The causes
of outbreaks are still not completely understood; it may be connected to overfishing of A.
planci predators, such as the giant triton shell which is popular with shell collectors, or to
natural fluctuations (CRC Reef 2001). The most influential factor could be increased nutrient
levels in the oceans (Engelhardt pers. comm.), from agricultural, domestic or industrial
sources. A. planci are surveyed as part of the invertebrate abundance and diversity belts
and incidental sightings are also documented after every dive. There were 37 recordings of
A. planci across all sites during January and March and a further 57 seen during April to
June 2012. Most sightings of A. planci were at Anse Major Reef and the adjoining Ray's
Point. These numbers are high in comparison to previous year's sightings, however are not
concerning.
6.3. Cetacean Sightings
Cetaceans are considered to be under threat in many parts of the world and in response to
this threat, a national database of cetacean sightings, the Seychelles Marine Mammal
Observatory (SMMO), has been set up. GVI records all incidental cetacean sightings and
passes all data to MCSS for inclusion in the national database. Data recorded includes
date, time, location (including GPS coordinates where possible), environmental conditions,
number of individuals, distinguishing features, size, behaviour and species. There were
only 4 separate recordings of dolphin sightings within January to June 2012. Pod sizes
ranged from 3 to 4 individuals and all were sighted from the boat.
6.4. Whale Shark Sightings
The Seychelles is famous for its seasonal fluctuations in the abundance of whale sharks
(Rhincodon typus). However despite their public profile, relatively little is known about their
behaviour or the ecological factors which influence their migratory patterns. A whale shark
monitoring programme was started by volunteers in 1996 and is now the cornerstone of a
54
lucrative eco-tourism operation run by MCSS. From 2001-2003, a tagging programme was
initiated to study migratory patterns as part of the Seychelles Marine Ecosystem and
Management Project (SEYMEMP); it is now clear that the sharks seen in the Seychelles
are not resident, but range throughout the Indian Ocean. The oceanographic or biological
conditions that determine the movements are unclear, it is possible however that the sharks
follow seasonal variations in the abundance of the plankton on which they feed. All
sightings of whale sharks are documented in as much detail as possible; including time,
date, GPS point, number, size of the individuals, sex, distinguishing features, behaviour
and tag numbers if present. Photographs are also taken whenever possible of the left and
right side of the thorax from the base of the pectoral fin to behind the gill area to be used as
identification in the global and regional database.
Within the January to June period there were three separate sightings of whale sharks. The
first sighting was at Baie Ternay North West on the 25/1/2012, coinciding with the very end
of the 2011 season. The last two sightings both occurred on the 17/6/2012 at two different
locations; Conception North Face and Lighthouse. These two sightings were 'early comers'
to the 2012 September- December season. All data collected, including any photographs
taken, were sent on to MCSS for inclusion into their database.
6.5. Plankton Sampling
MCSS initiated a plankton monitoring programme in conjunction with the tagging and
incidental recording surveys in an attempt to correlate the frequency of whale shark
sightings with plankton levels. Plankton sampling has been run by MCSS since 2003 in
conjunction with their on-going monitoring and tagging programmes. GVI started to assist
MCSS in the collection of plankton data in July 2004, and have since carried out the survey
on a weekly basis. Five plankton tows are carried out to the North West side of Grouper
Point, just outside of Cap Ternay, between 08:00 and 11:00 hours. The tows are carried
out along a North Westerly course from Grouper Point. In order to sample over a range of
depths the net is let out 5m every 30 seconds (up to 45m). Samples are collected in the
‘cod end’ of the net, decanted into a receptacle and preserved in formalin. After the survey
and the filtering process, they are sent to MCSS for measurement of wet weight and
species classification. Environmental conditions are also noted (sea state, cloud cover and
turbidity).
Plankton tows were successfully conducted each week from January to June and all
samples were sent on to MCSS for analysis.
55
7. Non-survey Programmes
7.1 Extra Programmes
7.1.1 Internships
GVI Seychelles currently runs a Divemaster Internship program in conjunction with their
marine research activities. Interns typically spend twelve weeks with GVI on the marine
expedition and then twelve weeks at a dive shop in the Seychelles gaining the PADI
divemaster qualification and professional divemaster experience. They also take courses
in Team Leadership and Supervision of Biological Surveys. We continued this program
with twelve divemasters successfully completing their internships at The Underwater
Centre, Big Blue Divers and Blue Sea Divers in Beau Vallon.
The Short Term Marine Conservation Internship program was also continued. Interns on
this program take a course in Team Leadership, and also gain experience and knowledge
of marine conservation whilst participating on the expedition.
7.1.2 GVI additional courses
GVI Seychelles has also expanded their programmes to include two additional courses.
These are in the Supervision of Biological Surveys and Team Leadership. These courses
are available to those on the internship programmes (see above) and the Biological
Surveys course can be added additionally to the expedition if volunteers so choose. Both
courses are designed to expand the skill set and knowledge that volunteers gain whilst on
the expedition/internship and to provide an accreditation for the work they complete. This
can then be used in reference to future employment in this field.
7.2 Community Development
7.2.1 International School Seychelles (ISS)
The GVI Seychelles community education program works in conjunction with the
International School of the Seychelles (ISS). Lessons are held on Port Launay Beach,
within one of the National Marine Parks on Mahé, where children aged 7-9 from ISS are
taught about the marine environment and marine conservation in a location that ignites and
stimulates their interest. During this six months the lessons conducted by volunteers were
tailored towards the Indian Ocean and the Seychelles in particular. This aspect of the
56
expedition is key to the overall impact of our role within the Seychelles. It also increases the
extent to which volunteers are able to contribute on an individual level, to help raise vital
awareness of marine conservation issues related directly to the Seychelles.
7.2.2 GVI Charitable Trust
As part of the GVI Charitable Trust, GVI Seychelles has partnered with the Presidents
Village Children’s Home in Port Glaud. The Presidents Village is part of The Children’s
Home Foundation, which has several children’s homes in the Seychelles. The Presidents
Village provides a home for abused, neglected and orphaned children and currently houses
56 children from birth to 18 years old. GVI volunteers during the past six months have
organized bi-weekly snorkel trips to Port Launay Marine Park for the children at Presidents
Village. Some of the children were able swimmers so were shown some of the fish and
corals by the volunteers which they attempted to identify back on the beach. Other children
are new swimmers and the experience is an introduction to water safety and an
appreciation of the marine environment. These snorkelling trips provide an opportunity for
the children to interact with other members of their local community and spend some time
away from the Children’s home in a structured, educational and fun activity.
In addition to the bi-weekly snorkel sessions, every quarter a ‘Creole Day’ is held at the
Presidents Village. GVI volunteers and staff attended two of these days in the past six
months with the children from the President’s Village. The day involves fun and creative
activities such as jewellery making and crafts, and then usually finished with some dancing,
games or a snorkel. These days are a great opportunity for the children to get some
additional care and attention, and for the volunteers to interact with members of the local
community.
GVI Seychelles is successfully raising funds for the Presidents Village to contribute towards
the costs of housing and clothing the children, as well as purchasing special items not
included in the children home’s budget. In the past six months two fundraisers have been
held at Cap Ternay to raise these funds. Our project partner SNPA joined one of the
fundraisers and both events have raised awareness in the local area of both GVI and the
Presidents Village. In total we raised just over £2000.
In the past six months a new initiative was started of providing swimming lessons for the
carers working at the Presidents Village. Many Seychellois residents cannot swim despite
their close proximity to the sea. Teaching water safety and swimming techniques to the
carers improves their interest and confidence in the ocean surrounding them. And more
57
importantly it means that they can take the children from the home swimming or snorkelling
whilst confident of their safety and the ability to rescue them if needed. So far two lessons
have been completed with ten Seychellois staff attending each session. These lessons will
continue over the next six months.
7.2.3 Other Community events
Alongside the Charitable Trust and ISS lessons GVI Seychelles also takes part in other
one-off community events and partnerships. GVI is continually seeking to extend their
reach in the local community and often these events are a way to educate and
communicate with new people.
GVI were invited by the Seychelles Ministry of Environment to host snorkelling activities as
part of a national ‘Biodiversity day’. This day was an opportunity for students from schools
around Mahe to experience the marine environment and learn more about it’s biodiversity.
Several other organisations also joined GVI staff and volunteers in hosting this day
including; Wildlife Clubs of Seychelles, MCSS, SNPA and Mangroves for the Future.
In April ‘Akyson pour lanvironmann’, a local youth group, invited GVI to attend an
environmental fair being hosted by their group at Port Glaud. At this one day event GVI set
up a stand with various environmental activities for visiting children to participate in.
Activities included: make a turtle, snorkelling in the marine park, ball games and many
more. Around 400 children of all ages from the local area attended the event. This was
linked in with the international event ‘Earth Day’. This worldwide event encourages people
to raise awareness of the environment and how it can be conserved.
7.2.4 National Scholarship Programme
As part of GVI’s local capacity program GVI runs a National Scholarship programme in
each country. The National Scholarship Programme is directly funded by GVI volunteers’
payments and aims to increase long-term capacity building within the country. National
recruits such as rangers, researchers and students are selected by the local partner
organisations and are brought into the programme as volunteers. In order for SNPA to
continue and build upon the research conducted by GVI, scholars are invited to join every
expedition from the pool of SNPA staff. Unfortunately we did not have any applicants for
the programme this phase.
58
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Achituv, Y., Dubinsky, Z. (1990) Evolution and zoogeography of coral reefs. In: Dubinsky Z (ed.) Ecosystems of the world. Elsevier, Amsterdam, pp 1–10
Bellwood, D. R., T. P. Hughes, C. Folke, and M. Nyström. (2004) Confronting the coral reef crisis. Nature 429:827–833.
Cassidy, L. (2011), GVI Phase Report 112 – Status of the Coral Reefs of North-West Mahé, Seychelles
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Coleman, N. (2000) Marine Life of the Maldives, Atoll Editions, Apollo Bay, Australia
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Ellis, D. M. & Balazs, G. H. (1998) Use of a generic mapping tools program to plot Argos tracking data for sea turtles, in S. P. Epperly and J. Braun (comp.) Proceedingsof the 17th Annual Symposium on Sea Turtle Biology and Conservation, NOAA Tech. Memo, NMFS-SEFSC-415, pp. 166–168
Engelhardt U. (2004) The status of scleractinian coral and reef-associated fish communities 6 years after the 1998 mass coral bleaching event. Seychelles Marine Ecosystem Management Project. Global Environment Facility/Government of Seychelles/World Wildlife Fund, Victoria.
Engelhardt U.M., Russell & Wendling B. (2003), Coral Communities around the Seychelles Islands 1998–2002, p.212 – p.231
Ferrier-Page`s, C., Gattuso , J.P., Dallot, S. & Jaubert, J. (2000) Effect of nutrient enrichment on growth and photosynthesis of the zooxanthellate coral Stylophorapistillata. Coral Reefs 19 : pp.103 – 113
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9. Appendices
Appendix A. Details of sites surveyed by GVI Seychelles – Mahé, year round. Sites in
bold-type text are located within Marine Protected Areas.
Site
NoSite Name GPS
Survey
StatusGranitic/Carbonate
1 Conception North Point S 04°39.583, E 055°21.654 Core Granitic
2Conception Central East
FaceS 04°39.891, E 055° 22.258 Core Carbonate
4 Port Launay West Rocks S 04º39.416, E 055º23.382 Core Granitic
5 Port Launay South Reef S 04º39.158, E 055º23.695’ Core Carbonate
7 Baie Ternay Lighthouse S 04°38.373, E 055°21.993 Core Granitic
8 Baie Ternay Reef North East S 04°38.013, E 055°22.405 Core Granitic
9 Baie Ternay Reef Centre S 04°38.321, E 055°22.504 Core Carbonate
10 Baie Ternay Reef North West S 04°38.382, E 055°22.133 Core Carbonate
11 Ray’s Point S 04°37.347, E 055°23.145 Core Granitic
12 A Willie’s Bay Reef S 04°37.650, E 055°22.889 Core Carbonate
12 B Willie’s Bay Point S 04°37.589, E 055°22.776 Core Granitic
13 A Anse Major Reef S 04°37.546, E 055°23.121 Core Carbonate
13 B Anse Major Point S 04°37.509, E 055°23.010 Core Granitic
14 Whale Rock S 04°37.184, E 055°23.424 Core Granitic
15 Auberge Reef S 04°37.024, E 055°24.243 Core Carbonate
16 Corsaire Reef S 04°37.016, E 055°24.447 Core Carbonate
17 White Villa Reef S 04º36.935, E 055º24.749 Core Carbonate
18 L’ilot North Face S 04°38.652, E 055°25.932 Core Granitic
19 Site Y S 04°37.771, E 055°22.660 Core Granitic
21 Therese North End S 04°40.101, E 055°23.737 Core Granitic
22 Therese North East S 04°40.099, E 055°23.891 Core Carbonate
23 Therese South S 04°40.764, E 055°24.310 Core Granitic
24 Site X S 04°37.059, E 055°23.783 Core Granitic
N/A Secret Beach Reef N/A Core Carbonate
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Appendix B. Scleractinian coral genera surveyed by GVI Seychelles - Mahé.
Acroporidae
Acropora
Fungiidae
Fungia
Astreopora Herpolitha
Montipora Diaseris
Pocilloporidae
Pocillopora Cycloseris
Stylophora Podabacia
Seriatopora Halomitra
Poritidae
Porites Polyphyllia
Goniopora
Faviidae
Favia
Alveopora Favites
Dendrophylliidae Turbinaria Montastrea
Siderastreidae
Siderastrea Plesiastrea
Pseudosiderastrea Goniastrea
Coscinaraea Echinopora
Psammocora Diploastrea
Mussidae
Lobophyllia Leptasrea
Symphyllia Cyphastrea
Acanthastrea Platygyra
Blastomussa Leptoria
Oculinidae Galaxea Oulophyllia
Euphyllidae Physogyra Astrocoeniidae Stylocoeniella
Pectinidae
Pectinia
Agaricidae
Pavona
Mycedium Leptoseris
Echinophyllia Gardineroseris
MerulinidaeMerulina Coeloseris
Hydnophora Pachyseris
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Appendix C. Fish families, genera and species surveyed by GVI Seychelles - Mahé.
FamilyScientific
name
Common
nameFeeding guild
Relevance
(Engelhardt
2004)
Butterflyfish
(Chaetodontidae)
Chaetodon
vagabundusVagabond C/I Coral recovery
Chaetodon auriga Threadfin C/I Coral recovery
Chaetodon trifascialis Chevroned C Coral recovery
Chaetodon
melannotusBlack-backed C/I Coral recovery
Chaetodon mertensii Merten's C/I Coral recovery
Chaetodon
triangulumTriangular C Coral recovery
Chaetodon
trifasciatusIndian Redfin C Coral recovery
Chaetodon
interruptus
Indian Ocean
TeardropC/I Coral recovery
Chaetodon bennetti Bennett's C Coral recovery
Chaetodon lunula Raccoon C/I Coral recovery
Chaetodon kleinii Klein's C/I Coral recovery
Chaetodon citrinellus Speckled C/I Coral recovery
Chaetodon
guttatisimusSpotted C/I Coral recovery
Chaetodon lineolatus Lined C/I Coral recovery
Chaetodon falcula Saddleback C/I Coral recovery
Chaetodon meyersi Meyer's C Coral recovery
Chaetodon
xanthocephalusYellow-headed C/I Coral recovery
Chaetodon
zanzibariensisZanzibar C Coral recovery
Forcipiger sp. Longnose sp. C/I Coral recovery
Angelfish
(Pomacanthidae)
Apolemichthys
trimaculatusThree-spot V Visual appeal
Pomacanthus
imperatorEmperor V Visual appeal
Pomacanthus
semicirculatusSemicircle V Visual appeal
Pygoplites diacanthus Regal V Visual appeal
Surgeonfish Acanthurus sp. Surgeonfish H Algae vs. coral
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(Acanthuridae)Ctenochaetus sp. Bristletooths H Algae vs. coral
Naso sp. Unicornfish Pl Algae vs. coral
Zanclus cornutus Moorish idol V Visual appeal
Rabbitfish
(Siganidae)
Siganus puelloides Blackeye H Algae vs. coral
Siganus corallinus Coral H Algae vs. coral
Siganus stellatus Honeycomb H Algae vs. coral
Siganus argenteus Forktail H Algae vs. coral
Siganus sutor African Whitespotted H Algae vs. coral
Snappers
(Lutjanidae)
Lutjanus gibbus Paddletail Pi Fishing pressure
Lutjanus sebae Red emperor Pi Fishing pressure
Lutjanus fulviflamma Longspot Pi Fishing pressure
Lutjanus kasmira Blue-lined Pi Fishing pressure
Lutjanus bengalensis Bengal Pi Fishing pressure
Lutjanus monostigma Onespot Pi Fishing pressure
Lutjanus vitta Brownstripe Pi Fishing pressure
Lutjanus fulvus Flametail Pi Fishing pressure
Lutjanus
argentimaculatusMangrove jack Pi Fishing pressure
Lutjanus bohar Red Pi Fishing pressure
Lutjanus russelli Russell's Pi Fishing pressure
Macolor niger Black Pi Fishing pressure
Aprion virescens Green jobfish Pi Fishing pressure
Triggerfish
(Balistidae)
Balistoides
viridescensTitan I Sea urchins & COTs
Sufflamen
chrysopterusFlagtail I Sea urchins & COTs
Balistidae Other triggerfish I Sea urchins & COTs
Emperors
(Lethrinidae)
Monotaxis sp. Redfin/Bigeye bream I Sea urchins & COTs
Gymnocranius
grandoculis
Blue-lined large-eye
breamI Sea urchins & COTs
Lethrinus olivaceous Longnosed I Sea urchins & COTs
Lethrinus nebulosus Blue-scaled I Sea urchins & COTs
Lethrinus
rubrioperculatusRedear I Sea urchins & COTs
Lethrinus
xanthochilusYellowlip I Sea urchins & COTs
Lethrinus harak Thumbprint I Sea urchins & COTs
Lethrinus lentjan Pinkear I Sea urchins & COTs
Lethrinus obsoletus Orange-striped I Sea urchins & COTs
Lethrinus Yellowfin I Sea urchins & COTs
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erythracanthus
Lethrinus mahsena Mahsena I Sea urchins & COTs
Lethrinus variegatus Variegated I Sea urchins & COTs
Groupers
(Serranidae)
Anyperodon
leucogrammicusSlender Pi Fishing pressure
Cephalopholis argus Peacock Pi Fishing pressure
Cephalopholis
urodetaFlagtail Pi Fishing pressure
Cephalopholis
miniataCoral Hind Pi Fishing pressure
Cephalopholis
sonneratiTomato Pi Fishing pressure
Epinephelus merra Honeycomb Pi Fishing pressure
Epinephelus
spilotocepsFoursaddle Pi Fishing pressure
Epinephelus
polyphekadionCamouflage Pi Fishing pressure
Epinephelus
caeruleopunctatusWhitespotted Pi Fishing pressure
Epinephelus
fuscoguttatusBrown-marbled Pi Fishing pressure
Epinephelus tukula Potato Pi Fishing pressure
Epinephelus fasciatus Blacktip Pi Fishing pressure
Aethaloperca rogaa Redmouth Pi Fishing pressure
Variola louti Yellow-edged Lyretail Pi Fishing pressure
Plectropomus laevis Saddleback Pi Fishing pressure
Plectropomus
punctatusAfrican Coral Cod Pi Fishing pressure
Sweetlips
(Haemulidae)
Plectorhinchus
orientalisOriental I Sea urchins & COTs
Plectorhinchus picus Spotted I Sea urchins & COTs
Plectorhinchus
gibbosusGibbus I Sea urchins & COTs
Parrotfish
(Scaridae)
Bolbometopon
muricatumBumphead parrotfish C/H Coral damage
Scaridae Other parrotfish H Algae vs. coral
Wrasse (Labridae)
Cheilinus trilobatus Tripletail I Sea urchins & COTs
Cheilinus fasciatus Redbreasted I Sea urchins & COTs
Oxycheilinus
digrammusCheeklined splendour I Sea urchins & COTs
Cheilinus undulatus Humphead I Sea urchins & COTs
Tetraodontidae Puffers I Sea urchins & COTs
Diodontidae Porcupinefish I Sea urchins & COTs
65
HolocentridaeSoldierfish Pl Upwelling areas
Squirrelfish Pl Upwelling areas
66
Appendix D. Fish feeding guilds analysed by GVI Seychelles – Mahé.
Code Feeding guild
Description (adapted from Obura and Grimsditch, 2009) Key species
Pl Planktivores
Resident on reef surfaces, but feed in the water column. Their abundance is related to quality of
reef habitat for refuge, and water column conditions.
Soldierfish, Squirrelfish, Unicornfish
Pi Piscivores
High level predators. Exert top-down control on lower trophic levels. Important fisheries species but very vulnerable to overfishing thus good indicators
of the fishing pressure on a reef.
Groupers, Snappers
C CorallivoresRelative abundance is an indicator of coral
community health
Butterflyfish (Chevroned, Triangular, Bennetts,
Indian Redfin, Meyers,
Longnose sp.)
V Varied diet
Feed on coral competitors such as soft corals and sponges. Relative abundances may be an indicator of abundance of these prey items and of a phase
shift.
Angelfish, Moorish Idol
I Invertivores*
Second-level predators with highly mixed diets including small fish, invertebrates and dead
animals. Important fisheries species thus abundances are a good indicator of fishing
pressure.
Sweetlips, Emperors, Pufferfish,
Porcupinefish, Wrasse
(Tripletail, Redbreasted, Cheeklined Splendor,
Humphead), Triggerfish
(Titan, Flagtail, Other)
H Herbivores
Exert the primary control on coral-algal dynamics. Parrotfish, Surgeonfish, Bristletooth, Rabbitfish
May indicate phase shift from coral to algal dominance in response to mass coral mortality or
pressures such as eutrophication.
C/HCorallivore/Herbivore
Relative abundance is a secondary indicator of coral community health
Bumphead parrotfish
C/I Corallivore/Invertivore
Relative abundance can be a secondary indicator of coral community health
Butterflyfish(Vagabond, Threadfin,
Blackbacked, Mertens, Indian
Ocean Teardrop, Racoon, Kleins,
Speckled, Spotted, Lined,
67
Saddleback, Yellow headed,
68
Appendix E. Fish species lists divided into commercial and reef species analysed by
GVI Seychelles – Mahé.
Commercial Fish Species Reef Fish Species
Siganidae (Rabbitfish) Chaetodontidae (Butterflyfish)
Lutjanidae (Snappers) Pomacanthidae (Angelfish)
Lethrinidae (Emperors) Acanthuridae (Surgeonfish)
Serranidae (Groupers) Balistidae (Triggerfish)
Haemulidae (Sweetlips) Labridae (Wrasse)
Scaridae (Parrotfish) Tetradontidae (Pufferfish)
Diodontidae (Porcupinefish)Holocentridae (Soldierfish & Squirrelfish)
Zanclus cornutus (Moorish Idol)
Bolbometopon muricatum (Bumphead Parrotfish)
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Appendix F. List of invertebrate species surveyed on 50m belt transects by GVI
Seychelles – Mahé.
Mollusca (Gastropoda) Drupella spp. Drupella
Mollusca (Bivalvia) Tridacnidae Giant Clam
Sea Stars (Asteroidea)
Culcita spp. Cushion Sea Star
Acanthaster planci Crown of Thorns Sea Star
Other Sea Stars
Sea Urchins (Echinoidea)
Diadema spp. Long Spine Urchin
Echinometra spp. Mathae’s Urchin
Echinothrix spp. Short Spine Urchin
Pencil Urchin
Toxopneustes pileolus Flower Urchin
Cake Urchin
Sea Cucumbers (Holothuroidea)
Holothuria artra Lollyfish
Holothuria fuscopunctata Elephant Trunk
Holothuria fuscogilva White teatfish
Holothuria nobilis Black teatfish
Holothuria sp.(undescribed) Pentard
Bohadschia spp. Bohadschia
Actinopyga spp. Actinopyga
Actinopyga mauritiana Yellow Surfish
Stichopus spp. Stichopus
Thelenota ananas Prickly Redfish
Pearsonothurian graeffei Flowerfish
Thelenota anax Royal
Holothuria edulis Edible Sea Cucumber
(Cephalopoda) Octopus spp. Common Reef Octopus
Lobsters (Palinura)Panulirus spp. Spiny Lobster
Parribacus spp./Scyllarides spp. Slipper Lobster
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Appendix G. Invertebrates surveyed on 10m LIT transects by GVI Seychelles – Mahé.
Annelida (Polychaeta)
Sabellidae Feather Duster worms
Serpulidae Christmas Tree worms
Terebellidae Spaghetti worms
(Platyhelminthes) Polycladida Flatworms
Arthropoda (Crustacea)
Caridea Shrimps
Stomatopoda Mantis shrimps
- Crabs
Mollusca (Gastropoda)
Muricidae Murex
Drupella sp. Drupella
Strombidae Conch
Cypraeidae Cowrie
Ranellidae Triton
Conidae Cone
Trochidae Top
Cassidae Helmet
- Other shells
Nudibranchia Nudibranchs
Mollusca (Bivalvia)Ostreidae Oysters
Tridacnidae Giant Clam
Mollusca (Cephalopoda)Sepoidea Cuttlefish
Teuthoidea Squid
Sea Stars (Asteroidea)
Culcita sp. Cushion Sea Star
Acanthaster planci Crown of Thorns Sea Star
Other Sea Stars
Ophiuroidea Brittle Stars
Crinoidea Feather Stars
Sea Urchins (Echinoidea)
Diadema sp. Long Spine Urchin
Echinometra sp. Mathae’s Urchin
Echinothrix sp. Short Spine Urchin
Pencil Urchin
Toxopneustes sp. Flower Urchin
Cake Urchin
Other Urchins
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