Ecological Baseline Survey of Anguilla’s Five
Marine Parks
Department of Fisheries and Marine Resources
Note: The conclusions and recommendations of this report are solely the opinions of the author and other contributors and do not
constitute a statement of policy, decision, or position on behalf of the Government of Anguilla. Citation: Wynne S. (2007). Ecological
Baseline Survey of Anguilla’s Five Marine Parks. Produced by the Department of Fisheries and Marine Resources for the Anguillian
National Trust as part of an Overseas Territories Environmental Programme funded project. Copies can be obtained by contacting
[email protected]
1
Table of Contents
1.0 Introduction
3
2.0 Methods
3
2.1 Choosing Survey Sites
2.2 Survey Techniques
3.0 Results
3.1 Dog Island
3.2 Prickly Pear
3.3 Sandy Island
3.4 Shoal Bay – Island Harbour
3.5 Little Bay
3.6 Across all Parks
4.0 Discussion
4.1 Fish Surveys
4.2 Habitat Surveys
3
4
6
6
7
8
9
10
11
14
14
16
5.0 Conclusions and Recommendations
17
Appendix I – Survey Site Descriptions and Coordinates
19
Appendix II – Notes on Data Analysis and Limitations
24
Appendix III – Example Datasheets
27
References
30
Two supplemental sections are available on request that contain further details than those presented within this report. The first of
these contains mean raw data tables from the survey work conducted, with the second offering tabulated results from a variety of
diversity indices for fish species and coral species, with brief comparative analysis and discussion.
2
1.0 Introduction
This report represents the contribution made by The Department of Fisheries and Marine
Resources (DFMR) towards phase 1 of the Anguillian National Trusts (ANT) project
‘Enhancing Marine Park Management’ that has been funded by Overseas Territories
Environmental Programme (OTEP). The results from this current aspect of the project,
that being the collection of baseline data for all five of Anguilla’s Marine Parks, will fill a
huge gap in the Departments knowledge base as well as being of vital importance for the
ANT project, and future management of the Marine Parks.
The contents of this report include methodologies used, details of the study sites
surveyed, initial results and short analysis/discussion. There are also comments on project
justification and notes relating to data limitations which are vital to consider if using this
report as the basis of further analysis that will potentially lead to the formulation of
management strategies. These comments are found in the end appendices.
2.0 Methods
The methodology used was chosen to compliment surveyor skill sets while appreciating
man-power and time limitations. Methods were of a relative rapid nature to allow three
surveyors to complete one study site during one dive.
2.1 Choosing Survey Sites
Thirty sites were chosen within the Marine Park boundaries, and distributed to satisfy two
criteria:
•
•
To accommodate the size and variety of use within each Marine Park. I.e. Larger
multiple use Marine Parks have more sites than smaller ones.
To be representative of the habitats found within the Marine Parks and evenly
distributed among them.
With these criteria in mind, the thirty sites were allocated among the five Marine Parks as
follows:
•
•
•
•
•
Dog Island – 3 Sites
Prickly Pear – 8 Sites
Sandy Island – 4 Sites
Shoal Bay & Island Harbour – 12 Sites
Little Bay – 3 sites
It should be noted that areas within these Parks, such as sand flats, with very little to
survey within them were avoided, thus effectively stratifying the sampling. This is not to
3
say sites were ‘cherry picked’ – a general area to survey was selected using the 1994
Natural Resource Institute (NRI) Atlas, which was subsequently visited for closer
inspection to decide if it was suitable for the purpose of this study. The area was
inspected using a bottom viewer and/or snorkeling equipment, and once a suitable
location was found within this area a GPS point was marked (‘suitable’ meaning
representative habitat within that area). All sites were established this way within each
Park before the survey work began in earnest. All current AMMP PMS (Anguilla Marine
Monitoring Programme Permanent Monitoring Sites – A monitoring scheme run by
DFMR) that are located within the Marine Parks were also used as sites for this project,
thus allowing results to be comparable. I.e. Out-of-park AMMP PMS will potentially be
comparable with the OTEP baseline dataset. Coordinates for all study sites, together with
site descriptions and a map of site locations can be found in appendix I.
2.2 Survey Techniques
Three survey techniques were employed to collect all the required information. As only
three surveyors were qualified to conduct this work (combined with the presence of time
constraints) survey replicates were limited. This is discussed later in the report. However,
all efforts were taken to standardize number of replicates per site within each park, and if
time permitted certain parks were revisited and further survey replicates conducted.
Surveys only took place between 7am and 11am to avoid bias, although in an extreme
circumstance (i.e. Dog Island - perfect weather in this logistically difficult site to reach)
this cut-off was pushed forward to 12 noon to allow work to be fully completed.
Sites were first located using a handheld GPS unit and the previously collected
coordinates. As the site was approached the boat driver indicated the distance remaining
until the site was reached, and upon arrival one of the surveyors drops a small weight into
the water that is attached to a surface marker buoy with rope. This then acted as a point of
reference for both the surveyors and the boat driver, with the marker considered to be
positioned in the center of the study site. From this point, once kitted up, three survey
types were conducted, one by each of the three surveyors present:
Fish Density & Species Diversity – Roving Diver Technique (RDT). One surveyor swam
for 30 minutes at a constant speed of 5m per min, thus allowing data to be quantifiable.
Fish were actively sought and all were recorded in a tally fashion (down to species level)
seen within 2.5 meters either side of the surveyor (thus giving a ‘belt’ of five meters). To
avoid counting the same fish twice swimming direction was random but did not cover the
same area more than once. The survey boundary was again set as no more than 50m from
the central marker and no deeper than 10m. The RDT methodology effectively records
accurately both rare and common species and those that can often be overlooked. Two
replicates were conducted at each site. See appendix III for example datasheet with the
most common species listed prior to survey (other species sighted can be noted by hand).
These data will not only be used for DFMR/ANT purposes but also submitted to REEF
for inclusion in their online database.
4
Fish Size Class Distribution – Stationary Point Counts (SPC). A starting position was
randomly selected by the surveyor, and that position held for a minimum of three minutes
to allow fish behavior to return to normal after potential disturbance. Each count took
place over a period of six minutes while the surveyor slowly rotated and tallied fish seen
into family and fish size class (into 5cm size categories). The main emphasis was to
record individuals from families that are known to be either commercially or ecologically
important. Only those individuals within five meters of the surveyor were recorded, thus
allowing data to be quantifiable if so required. Family groups (see datasheet in Appendix
III) were chosen to survey rather than species because it was deemed more realistic for a
single surveyor to achieve, and such a compromise will still yield important information
relating to overall health of fish family populations via size class distribution analysis.
Once each count was completed the surveyor moved to another random location and
began the process again. All counts were carried out in representative habitat no more
than 50 meters from the marker, and no deeper than 10m. Five replicates were conducted
at each site.
Habitat Assessment – Quadrats (0.5m x 0.5m) were randomly distributed around the site
in a stratified fashion so not to include unrepresentative habitat. For example, if a reef
slope was being surveyed, no quadrats were placed on the sand at the bottom of the slope.
No quadrats were placed further than 50m from the marker even if the habitat still
appeared representative, or in water deeper than 10m. Within each quadrat certain criteria
were measured, broken down into three subcategories (physical characteristics,
underlying substrate composition, and percentage cover of biota) as illustrated on the
datasheet in Appendix III. On the whole the survey categories were generic to
compliment surveyor skill sets and time available, although there were spaces for details
to be recorded if necessary. For example in one box the surveyor recorded percentage
cover of sponges within a quadrat and number of individual sponges present. Details
were taken on the type of sponge, split into categories: Vase/barrel, tube, rope, ball and
encrusting. However, the surveyor was encouraged to ID the sponge species (i.e. Red
encrusting sponge rather than just encrusting sponge) and there was space available on
the datasheet for this information to be recorded. The surveyor was also encouraged to go
into more detail by noting percentage covers and numbers of each category of sponge.
The basic philosophy being the more details collected within the time available the better.
Some of the other categories used are explained in the following bullet points:
•
Algae/Plants
Turf algae – Including that with sediment amongst it
Fleshy algae – Dictyota sp, Lobophora sp, etc
Calcareous algae – i.e. Halimeda sp, Amphiroa sp, etc
Other macroalgae – i.e. Caulerpa sp, Turbinaria sp, etc
Coralline – Including both crustose coralline algae and reef cement
Seagrass – Thalassis sp, Syringodium sp, etc
Cyanobacteria – Just giving descriptive term, i.e. fuzz ball alga
5
•
Corals
Hard (Stony) Corals – The reef building Hexacorals. Recorded down to species.
Soft – The Octocorals, split into fans, rods, whips and plumes.
Fire – The Hydrocorals, recorded generically.
Although percentage cover of generic groups were the main variables recorded, some
physical readings were also taken. These were bottom temperature, quadrat depth,
quadrat relief (difference between highest and lowest point) and rugosity (length of 1m
chain when draped over substrate). If possible details were also recorded relating to coral
disease and bleaching, although this largely depended on the surveyor’s ability. A
minimum of 10 quadrats were surveyed per site, with special effort being targeted at
Shoal Bay & Island Harbour Marine Park where a minimum of 15 replicates were set to
increase the robustness of the dataset. This Marine Park is currently of most interest to
the ANT as they have already completed a socioeconomic study of the Park and are
currently working on a proposed management plan for the area.
3.0 Results
Notes on data collected can be found in Appendix II. The full raw dataset is available as a
Microsoft Excel file on the accompanying CD, or by contacting the Department of
Fisheries and Marine Resources (DFMR) or the Anguillian National Trust (ANT).
Alternatively see Supplement 1, available as a separate document, for a detailed
breakdown of mean site characteristics. It should be noted that the common names used
for fish species (and indeed other life forms) are those names proposed by Humann &
Deloach (1989). Photographs of the study sites can also found either on the
accompanying CD, or again by contacting DFMR/ANT. The results presented below are
a summary of these results, split into the five Marine Parks, and the areas within them. A
more detailed statistical analysis of these data would be possible, although this does not
fit into the scope of this project report.
3.1 Dog Island (reef site)
RDT: The most commonly occurring species surveyed within the three Dog Island study
sites were Blue Tang (Acanthurus coeruleus), Bar Jack (Caranx ruber), Caesar Grunt
(Haemulon carbonarium), Bicolor Damselfish (Stegastes partitus), Bluehead Wrasse
(Thalassoma bifasciatum) and Black Durgon (Melichthys niger). The total number of
species recorded were 72 (mean per site 46), with an encounter rate of c.38 fish min-1.
The mean fish density across all sites was 15473 fish ha-1, with the highest densities seen
at site DG02 and DG03 (18493 fish ha-1 and 17040 fish ha-1 respectively).
SPC: A graph representing the fish family size class distributions for all families
combined across the three Dog Island sites is presented in figure 1a. Triggerfish
(Balistidae), comprising mainly Black Durgon (Melichthys niger), were the largest
individuals recorded, although Surgeonfish (Acanthuridae) were slightly more abundant.
Mean relative abundance across all sites was 123 individuals survey-1, which is again the
6
highest for all of the Marine Parks. Of the sites, DG02 again exhibited the highest relative
abundance of fish (197 individuals survey-1), and also housed the largest individuals
across most of the families surveyed, and overall when families combined. The mean fish
family size class recorded across all sites was 20-25cm, with a precise value of 20.7cm.
Habitat: Overall, the underlying substrate of the three Dog Island sites combined was
established as 52.5% solid, 19.8% rubble and 27.7% sand. Physical characteristics
included a mean rugosity value of 67.8, relief of 7.0cm and depth of 7.8m. Percentage
biotic/barren covers across the sites were: 21.2% sand, 28.3% turf algae and/or sediment,
9.7% fleshy algae, 6.3% coralline algae, 2.3% Cyanobacteria, 7.7% hard coral, 8.0% soft
coral, 6.9% fire coral, 8.1% sponge (0.8 individuals m-1) and 2.4% other invertebrates
(1.6 individuals m-1) including, for example, White Encrusting Zoanthids (Palythoa
caribaeorum). Of the sites DG02 was concluded to be the most ‘healthy’, with 4.0%
sand, 37.5% turf algae and/or sediment, 8.5% coralline algae, 3.8% Cyanobacteria, 8.8%
hard coral, 12.5% soft coral, 7.3% fire coral, 13.0% sponge (1.0 individuals per 0.5m2)
and 5.5% other invertebrates (2.1 individuals per 0.5m2). Note: 0% fleshy algae. The
most common species of hard coral seen at this site (and indeed equally across all three
sites) were Mustard Hill (Porites astreoides) and brain corals – mainly Grooved Brain
Coral (Diplora labyrinthiformis). For a definition of ‘health’ in relation to this report
please refer to Appendix II.
3.2 Prickly Pear (reef site)
RDT: The most commonly occurring species surveyed within the eight Prickly Pear study
sites were Blue Tang (Acanthurus coeruleus), Brown Chromis (Chromis multilineata),
Striped Parrotfish (Scarus iserti), and Bluehead Wrasse (Thalassoma bifasciatum). The
total number of species recorded were 94 (mean per site 47), with an encounter rate of
c.30 fish min-1. The mean fish density was 12199 fish ha-1, with the highest density seen
at sites PP01 and PP07 (17800 fish ha-1 & 15686 fish ha-1 respectively). The site with the
lowest density was PP04 with 9100 fish ha-1.
SPC: A graph representing the fish family size class distributions for all families combined
across the eight Prickly Pear sites is presented in figure 1b. Parrotfish (Scaridae), had the
largest overall individuals within families recorded, and were also the most abundant.
Mean relative abundance across all sites was 75 individuals survey-1. Of the sites, PP04
exhibited the highest relative abundance of fish (139 individuals survey-1), and also housed
the largest individuals across most of the families surveyed, and overall when families
combined. This particular result is contra to the RDT surveys for Prickly Pear, and is
discussed later. See also Appendix II. The mean fish family size class recorded across all
sites was 15-20cm, with a precise value of 17.0cm.
Habitat: Overall, the underlying substrate of the eight Prickly Pear sites combined was
established as 35.6% solid, 24.1% rubble and 40.3% sand. Physical characteristics
included a mean rugosity value of 61.9, relief of 10.4cm and depth of 7.2m. Percentage
biotic/barren covers across the sites were: 27.9% sand, 17.0% turf algae and/or sediment,
5.1% fleshy algae, 5.8% calcareous algae, 3.9% coralline algae, 4.5% Cyanobacteria,
7
12.8% hard coral, 7.8% soft coral, 4.4% fire coral, 5.3% sponge (0.6 individuals per
0.5m2) and 5.8% other invertebrates (1.1 individuals per 0.5m2). Of the sites, PP07 was
concluded to be the most ‘healthy’, with 21.5% sand, 11.5% turf algae and/or sediment,
7.8% calcareous algae, 6.7% coralline algae, 7.5% Cyanobacteria, 24.5% hard coral,
10.5% soft coral, 4.5% fire coral, 5.0% sponge (0.6 individuals per 0.5m2) and 1.2%
other invertebrates (0.8 individuals per 0.5m2). Note: 0% fleshy algae. The most common
species of hard coral seen at this site were Finger Coral (Porites porites) and Mustard
Hill (Porites astreoides).
3.3 Sandy Island (reef site)
RDT: The most commonly occurring species surveyed within the four Sandy Island study
sites were Ocean Surgeonfish (Acanthurus bahianus), Bicolor Damselfish (Stegastes
partitus), and Bluehead Wrasse (Thalassoma bifasciatum). The total number of species
recorded were 71 (mean per site 45), with an encounter rate of c.33 fish min-1. The mean
fish density was 13045 fish ha-1, with the highest seen at site SA03 (16060 fish ha-1). The
site with the lowest density was SA02 with 10140 fish ha-1.
SPC: A graph representing the fish family size class distributions for all families
combined across the four Sandy Island sites is presented in figure 1c. Parrotfish
(Scaridae), had the largest individuals overall within recorded families, although
Surgeonfish (Acanthuridae) were the more abundant. Mean relative abundance across all
sites was 53 individuals survey-1 – interestingly the lowest of all Marine Parks. Of the
sites, SA01 exhibited the highest relative abundance of fish (65 individuals survey-1),
although SA04 housed the largest individuals across most of the families surveyed, and
overall when families combined. The mean fish family size class recorded across all sites
was 10-15cm, with a precise value of 13.6cm.
Habitat: Overall, the underlying substrate of the four Sandy Island sites combined was
established as 31.3% solid, 28.9% rubble and 39.9% sand. Physical characteristics
included a mean rugosity value of 65.7, relief of 11.3cm and depth of 6.9m. Percentage
biotic/barren covers across the sites were: 23.1% sand, 18.9% turf algae and/or sediment,
9.8% fleshy algae, 0.2% calcareous algae, 4.9% coralline algae, 0.4% Cyanobacteria,
11.0% hard coral, 15.8% soft coral, 5.1% fire coral, 9.8% sponge (1.0 individuals per
0.5m2) and 1.0% other invertebrates (0.4 individuals per 0.5m2). Of the sites, SA01 was
concluded to be the most ‘healthy’, with 24.0 sand, 20.5% turf algae and/or sediment,
6.0% fleshy algae 3.0% coralline algae, 12.0% hard coral, 15.0% soft coral, 4.0% fire
coral, 13.5% sponge (0.9 individuals per 0.5m2) and 1.5% other invertebrates (0.3
individuals per 0.5m2). The most common species of hard coral seen at this site was
Mustard Hill (Porites astreoides). It should be noted however that site SA03 exhibited
better values for some variables than SA01, but overall the dataset suggested it to be
more ‘healthy’. For a definition of this term see Appendix II.
8
3.4 Shoal Bay - Island Harbour (reef site)
RDT: The most commonly occurring species surveyed within the twelve Shoal Bay and
Island Harbour study sites were Blue Tang (Acanthurus coeruleus), Ocean Surgeonfish
(Acanthurus bahianus) and Bluehead Wrasse (Thalassoma bifasciatum). The total
number of species recorded were 100 (mean per site 51), with overall densities at many
of the sites lower than in the other reef dominated Marine Parks, with (SB07 being the
lowest at 6800 fish ha-1). The highest density was recorded at SB05 with 15213 fish ha-1,
followed by SB02 with 14400 fish ha-1, SB06 with 14300 fish ha-1 and SB03 with 13980
fish ha-1. Mean overall encounter rate across all sites was c.27 fish min-1.
SPC: A graph representing the fish family size class distributions for all families
combined across the twelve Shoal Bay - Island Harbour sites is presented in figure 1d.
Parrotfish (Scaridae), had the largest overall individuals within families recorded,
although Surgeonfish (Acanthuridae) were the more abundant. Mean relative abundance
across all sites was 88 individuals survey-1. Of the sites, SB02 exhibited the highest
relative abundance of fish (142 individuals survey-1), although SB08 housed the largest
individuals across most of the families surveyed, and overall if all families combined
(although larger parrotfish were seen at SB10). On the whole, fish were markedly smaller
compared to other reef dominated Parks with, for example, Parrotfish (Scaridae) not
exceeding 30cm in size at over half the study sites, and not exceeding 20cm at a quarter
of them. Even those sites with larger parrotfish had very low densities present. The mean
fish family size class recorded across all sites was 10-15cm, with a precise value of
11.9cm.
Habitat: Overall, the underlying substrate of the twelve Shoal Bay - Island Harbour sites
combined was established as 60.6% solid, 28.5% rubble and 10.9% sand. Physical
characteristics included a mean rugosity value of 49.0, relief of 14.0cm and depth of
7.0m. Percentage biotic/barren covers across the sites were: 13.9% sand, 30.2% turf algae
and/or sediment, 17.7% fleshy algae, 7.9% calcareous algae, 6.0% coralline algae, 0.2%
other algae, 3.7% Cyanobacteria, 6.6% hard coral, 5.4% soft coral, 2.2% fire coral, 4.7%
sponge (0.7 individuals per 0.5m2) and 1.4% other invertebrates (0.5 individuals per
0.5m2). Of the sites, SB02 was concluded to be the most ‘healthy’, with 16.4 sand, 9.9%
turf algae and/or sediment, 17.7% fleshy algae, 9.1% calcareous algae, 10.3% coralline
algae, 3.1% Cyanobacteria, 13.7% hard coral, 9.6% soft coral, 2.4% fire coral, 2.8%
sponge (0.4 individuals per 0.5m2) and 5.5% other invertebrates (1.2 individuals per
0.5m2), mainly White Encrusting Zoanthids (Palythoa caribaeorum). There was a good
variety of hard coral at this site with the most common species judged to be Mustard Hill
(Porites astreoides). Again, as with Sandy Island, it should be noted that other sites
exhibited ‘healthier’ values for some variables (i.e. lower fleshy algae cover) than SB02,
but on the whole the dataset suggested this site to be more ‘healthy’.
9
20
Frequency (mean per survey)
Frequency (mean per survey)
30
20
10
0
0-5
0
5-10
1a
10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50
50+
0-5
10-15 15-20 20-25
25-30 30-35 35-40
40-45 45-50
50+
40-45 45-50
50+
Size Class (cm)
30
Frequency (mean per survey)
Frequency (mean per survey)
5-10
1b
Size Class (cm)
20
10
0
0-5
10
20
10
0
5-10
10-15 15-20 20-25
25-30 30-35 35-40
40-45 45-50
50+
0-5
5-10
10-15 15-20 20-25
25-30 30-35 35-40
Size Class (cm)
Size Class (cm)
1c
1d
Figure 1 (a-d): Mean frequencies of fish size class for the four reef dominated sites, Dog
Island (1a), Prickly Pear (1b), Sandy Island (1c) and Shoal Bay-Island Harbour (1d).
3.5 Little Bay (seagrass site)
RDT: The most commonly occurring species surveyed within the three sites at Little Bay
was Slippery Dick (Halichoeres bivittatus). Also recorded in high numbers (over 250 fish
ha-1) were juvenile Grunts (Haemulon sp.), juvenile Yellowtail Snapper (Ocyurus
chrysurus), juvenile Redband Parrotfish (Sparisoma aurofrenatum) and Blackear Wrasse
(Halichoeres poeyi). The total number of species recorded were 35 (mean per site 21),
with an encounter rate of c.10 fish min-1. The mean density of fish across all sites was
4173 fish ha-1.
10
SPC: All fish recorded in Little Bay were smaller than 10cm (note: Wrasse were not
counted using this method, and some Slippery Dick were seen larger than this), and
juveniles (again with the exception of Wrasse that were not surveyed). The relative
abundance across the sites was 13 individuals survey-1. Of interest, although not seen
during a survey, was a juvenile Nassau Grouper (see plates at end of section).
Habitat: Overall, the underlying substrate of the three Little Bay sites combined was
established as 0.2% rubble and 99.8% sand, with a depth of 8.9m. Percentage
biotic/barren covers across the sites were: 17.5% sand, 4.2% turf algae and/or sediment,
0.5% fleshy algae, 13.5% calcareous algae, 1.0% other algae, 61.1% turtle grass, 0.7%
Cyanobacteria, 0.1% hard coral, 0.7% sponge (0.3 individuals per 0.5m2) and 0.6% other
invertebrates (0.1 individuals per 0.5m2). The only hard coral noted was Rose Coral
(Manicina areolata). Only one Queen Conch (Strombus gigas) was recorded which was a
juvenile, thus giving a density of 0.1 individuals per m2.
3.6 Across all Parks
As Little Bay Marine Park was the only seagrass area surveyed it will be left out from
this section and comparisons only made between the four coral reef regions.
RDT: The most commonly occurring species surveyed were Bluehead Wrasse
(Thalassoma bifasciatum), see plates at end of section. Other ranking species were Blue
Tang (Acanthurus coeruleus), Ocean Surgeonfish (Acanthurus bahianus) and Bicolor
Damselfish (Stegastes partitus). Also occurring in high numbers (over 500 individuals
ha-1) were Bar Jack (Caranx rubber), Brown Chromis (Chromis multilineata), and
Striped Parrotfish (Scarus iserti). Other high densities (between 250 and 500 individuals
ha-1) were recorded for French Grunt (Haemulon flavolineatum), Caesar Grunt
(Haemulon carbonarium), Longfin Damselfish (Stegastes diencaeus), Blue Chromis
(Chromis cyanea), Stoplight Parrotfish (Sparisoma viride), Princess Parrotfish (Scarus
taeniopterus), Redband Parrotfish (Sparisoma aurofrenatum), Slippery Dick
(Halichoeres bivittatus) and Black Durgon (Melichthys niger). The total number of
species recorded were 122, with an encounter rate of c.33 fish min-1. The density of fish
across all sites was 12870 fish ha-1. Grouper densities were low throughout all sites, with
the most common being the Coney (Cephalopholis fulvus) that had a density of 38
individuals ha-1. All other grouper species had a density of less than seven individuals
ha-1, with no Nassau Groupers (Epinephelus striatus) being recorded at all.
The five sites with densest fish populations were: DG02 (18493 fish ha-1), PP01 (17800
fish ha-1), DG03 17040 fish ha-1, SA03 (16060 fish ha-1) and PP07 (15686 fish ha-1). The
five lowest sites were: SB07 (6800 fish ha-1), SB04 (7793 fish ha-1), SB11 (7986 fish
ha-1), SB12 (8806 fish ha-1) and PP04 (9100 fish ha-1). It is interesting to note that four of
the five lowest density sites, and none of the five highest density sites, were found in
Shoal Bay - Island Harbour Marine Park. Across the parks as whole Dog Island exhibited
the highest densities of fish, followed by Sandy Island, Prickly Pear and finally Shoal
Bay - Island Harbour.
11
SPC: Table 1 details the fish family size class distributions for all families combined
across all reef dominated Marine Parks, mean totals of which are represented in figure 2.
Table 1: Fish family size class distributions for all families combined across all Marine Parks.
The values represent mean number seen per 6 minute survey. Average survey depth was 5.95
meters. See figure 6 for graphical representation.
Size Class (cm)
<5
Angelfishes
Butterflyfishes
Surgeonfishes
Jacks
Grunts
Snappers
Damselfishes
Groupers
Parrotfishes
Triggerfishes
Barracuda
Hogfishes
Goatfishes
Moray Eels
Totals
0.04
0.18
3.35
0.04
0.31
0.01
4.04
0
1.79
0.02
0
0
0
0
9.78
5-10
10-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
>50
Totals
0.12
0.35
4.46
0.91
0.31
0.09
4.57
0.01
2.37
0
0
0.02
0.09
0
13.30
0.17
0.41
6.97
1.11
0.34
0.10
3.27
0.02
4.01
0
0
0
0
0
16.38
0.09
0.12
8.67
2.10
1.92
0.28
1.60
0.12
2.22
0.97
0
0
0
0
18.10
0.13
0
4.40
1.15
2.51
0.97
0
0.24
2.04
1.40
0
0
0
0
12.83
0.08
0
0.88
0.25
2.09
1.08
0
0.16
1.25
1.38
0
0
0
0
7.16
0.01
0
0
0.13
0.44
0.04
0
0.15
0.89
2.06
0
0
0
0.01
3.73
0
0
0
0
0.06
0.03
0
0.13
0.71
1.21
0
0.01
0
0.01
2.17
0
0
0
0.01
0
0
0
0.06
0.65
0.03
0
0
0
0.01
0.77
0
0
0
0
0
0.02
0
0.03
0.38
0.04
0
0
0
0
0.45
0
0
0
0.01
0
0
0
0
0.02
0
0.07
0
0
0.02
0.11
0.63
1.05
28.73
5.72
7.99
2.60
13.47
0.91
16.32
7.11
0.07
0.03
0.09
0.05
84.79
Frequency (mean per survey)
20
10
Figure 2: Mean frequency of fish size
class across the four reef dominated
sites combined.
0
0-5
5-10
10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50
50+
Size Class (cm)
Parrotfish (Scaridae), had the largest overall individuals within families recorded,
although Surgeonfish (Acanthuridae) were the more abundant. Mean relative abundance
across all sites was 85 individuals survey-1. The site with largest Parrotfish was PP04.
Dog Island had the overall mean largest fish of commercial and/or ecological importance
(20.7cm) and Shoal Bay - Island Harbour the smallest (11.9cm). Two important families
of interest that should be mentioned are Groupers and Jacks. Of all grouper species the
Coney was the most abundant, with an overall density across coral reef dominated sites
of c.38 individuals ha-1. All other species had a density of less than 7 individuals ha-1,
12
which is very low indeed. Jacks also didn’t rank as highly as would have been expected,
with most sites having no individuals recorded larger than 20cm. Their mean size across
all sites was 16.7cm, although a couple larger individuals were recorded at a small
number of sites.
Habitat: Overall, the underlying substrate of the twenty seven reef sites combined was
established as 45.0% solid, 25.3% rubble and 29.7% sand. Physical characteristics
included a mean rugosity value of 61.1, relief of 10.7cm and depth of 7.2m. Percentage
biotic/barren covers across the sites were: 21.5.9% sand, 23.6% turf algae and/or
sediment, 10.6% fleshy algae, 3.5% calcareous algae, 5.3% coralline algae, 0.1% other
algae, 2.7% Cyanobacteria, 9.5% hard coral, 9.2% soft coral, 4.7% fire coral, 7.0%
sponge (0.8 individuals per 0.5m2) and 2.7% other invertebrates (0.9 individuals per
0.5m2). Of the sites, PP07 was concluded to be the most ‘healthy’, with characteristics as
described previously. The most common species of coral was judged to be Mustard Hill
(Porites astreoides), followed by finger coral (porites porites) – see following plates.
Color Plates: Clockwise from top left: Juvenile Nassau grouper seen in Little Bay; Mustard Hill, the most
commonly occurring coral species; Bluehead Wrasse, the most commonly occurring fish species; and a
large Finger Coral colony, probably the second most common coral species, photographed at site SA03.
13
4.0 Discussion
4.1 Fish Surveys – both RDT and SPC survey types
Results show that there is a tendency for densest populations of fish, with the largest
individuals, to be found around the off-shore cays, especially those areas that are more
logistically difficult to visit (i.e. more inaccessible & exposed). For example PP04, which
is found on the north coast of Seal Island (part of the Prickly Pear Marine Park), housed
the largest individual parrotfish. According to SPC results it also had the highest relative
abundance of commercially and/or ecologically important species (This result is contra to
that found when conducting RDT surveys, although this could be an artifact of the
sampling method and is discussed both later and in Appendix II). This result is especially
interesting when relating it to habitat results, as PP04 has the least rugose reef structure of
all Prickly Pear site surveyed, the second highest fleshy algae cover and the second
lowest live hard coral cover. This essentially sets it among the least ‘healthy’ Prickly Pear
sites, a fact that inaccessibility of the area likely mitigates when considering site
favorability for a dense fish population(within reason). By this it is meant that there
seems a possibility of inaccessibility leading to lower fishing pressure, and therefore ‘safe
houses’ for fish populations.
Further examples of inaccessibility possibly influencing fish SPC results (i.e. primarily
size class distribution) can be highlighted when looking at mean size of individuals
surveyed. Dog Island, the most distant site (with visitation largely weather depending and
inaccessible for many weeks of the year), had the largest mean fish size of 20.7cm (size
class 20-25cm), with Prickly Pear (some sites accessible, others more inaccessible)
having the second largest figure of 17.2cm (size class 15-20cm). Sandy Island, which is
easily accessible but a short distance off-shore, had a mean fish size of 13.7cm (size class
10-15cm), whereas Shoal Bay - Island Harbour, the most accessible Marine Park (it is
mainland coastal) had the smallest mean fish size of 11.9cm. This does admittedly put it
in the same size class category as Sandy Island, although when looking at the habitat
data, Shoal Bay - Island Harbour would appear to have a more complex (higher rugosity
and relief values) and therefore potentially better fish habitat. It is known from previous
studies (Wynne & Côté 2007) that higher quality habitat can mitigate impacts from
fishing, and it is known that fishing in Shoal Bay - Island Harbour is indeed intense.
Sandy Island reportedly has moderately high fishing activity, although the number of
traps observed (pers. obs.), and poorer accessibility for spear fishers (with Shoal Bay Island Harbour being ideal for this), mean this intensity is likely much lower. This being
the case, Sandy Island has possibly suffered more from a lower intensity of fishing than
Shoal Bay - Island Harbour would have, although because in this latter Park fishing
intensity is thought to be that much higher habitat mitigation has lead to both Parks being
in a somewhat similar state in terms of mean fish size class. This is further backed up by
the relatively low complexity of the study sites around Dog Island, and those having the
largest, mean fish size of all the Marine Parks.
14
Similar results were yielded from RDT surveys, where the densest populations of fish
were found around Dog Island and the least dense in Shoal Bay - Island Harbour Marine
Park. When considering the other two Park areas results vary, with Sandy Island having
the largest mean value, although Prickly Pear has the highest value of any particular site
across both regions. Because RDT fish density results include those species not targeted
by fishers and that are often too small to even be caught as by-catch these results do not
necessarily relate to the same issues as previously speculated, but paint a rather more
complex picture of other factors that can effect fish distribution. Deciphering these
factors would require a more in-depth analysis than is presented here. It does however
compliment the SPC size class results and suggest that Dog Island is the ‘healthiest’
region from a fish point of view over the other three coral reef dominated Marine Parks,
and special attention should be given to it when considering management options in order
to conserve it as such. Having said this, Shoal Bay - Island Harbour with the smallest
individuals and least dense populations across all of the coral reef dominated Marine
Parks doesn’t represent a ‘lost cause’ and again should be given special attention in order
to manage it in such a way as to not let it degrade any further. After all, with the highest
number of species counted (all other parks had a very similar number of species recorded,
suggesting Shoal Bay – Island Harbour is special from a diversity point of view),
combined with the highest mean number of species recorded at each site and a relatively
healthy population of juveniles (i.e. smaller individuals), there is plenty of scope for
action, but it is urged sooner rather than later. It is an interesting fact that this Park has the
highest recorded species diversity, a strong case for urgent attention to be paid to in from
a conservation point of view. It should be noted that relative densities of commercially
and/or ecologically important species from SPC surveys ranked Shoal Bay - Island
Harbour second under Dog Island (although individuals were indeed markedly smaller),
contra to RDT results. A more detailed analysis, possibly breaking down the RDT results
into family groups as with SPC surveys, may yield different results than discussed above
and explain such contra results. Alternatively, specific families may be looked at (see
below), again removing inconsistencies that might be present when grouping all fish
families together. This will likely be an area investigated on a deeper level during
subsequent and more detailed analysis.
Results suggest that grouper populations are much reduced from that supposed
historically. Nassau grouper for example, are known to have been abundant a few
decades ago, although during this project no individuals were recorded. It is known on a
regional level that they have been over-exploited due to harvesting their spawning
aggregations in an extremely efficient manner. One juvenile was sighted in Little Bay,
although not during a survey, and also sub-adults have been sighted during other work
conducted by DFMR, although admittedly not on a regular basis. Their populations are at
such a low level that they have become an exciting sight, almost making a dive special,
rather than a commonly sighted species of great commercial interest. They can currently
be classed as commercially extinct in Anguilla and it is suggested that protective
management be employed in the near future to try and encourage their re-establishment.
Having said this, groupers are generally quite reclusive and often cryptic in nature (the
Coney might be seen as being the least so, possible explaining it’s higher recorded
density), so this may partially explain results. However, the extreme paucity of Nassau
15
grouper suggests that even though a cryptic nature may reduce observability, it would not
explain the results of this study and so represents a marked reduction in density of a
previously abundant species. This can therefore possibly be extrapolated to all grouper
species, although lacking historical information firm conclusions can’t be draw. It should
be noted that Dog Island once again had the highest number of individuals recorded.
4.2 Habitat Surveys
Results from the habitat surveys suggests that a variety of health states exist throughout
the Marine Parks, from high/moderate to bad. It is difficult to conclude the overall health
of all Parks combined because of the extremely complex set of ecological interactions
that occur within a coral reef ecosystem, however what is clear is that the mean live hard
coral cover is rather low at 9.5%. Fleshy algae cover varies from 0% to almost 35%,
which highlights the variation within habitats present in Anguillian coral reef dominated
areas. If one site were to be chosen as the most ‘healthy’ it would have to be PP07, which
was recorded to have the highest live coral cover of all sites at 24.5% and 0% fleshy
algae. Fish density here was also within the top five sites, although it should be noted that
SPC results didn’t reflect this.
The seagrass areas surveyed in Little Bay are concluded to be in good health, although
there was a reduction in percentage of seagrass noted when compared to the Oxenford &
Hunte study of 1990, where the present cover of 61.1% shows a marked reduction from
their recorded value of 82.3%. The map of Little Bay produced by Oxenford & Hunte
suggests that the size of seagrass beds have much reduced over the last 17 years. There
are also some changes in fish composition, for example, the presence of Yellowtail
Parrotfish (Sparisoma rubripinne). However, precise data are hard to extract and the
exact locations of the study sites not entirely clear, making robust comparisons difficult
to make: Yellowtail Parrotfish are known to exist around the more rocky regions on the
periphery of the seagrass bed here.
The Dog Island site DG02 was in an almost identical location to one of the sites studied
by Oxenford & Hunte in 1990. Although it is recognized that even a difference of a few
hundred meters can make all the difference when making such comparisons, it does offer
the chance to do so, and combined with Little Bay represents one of the only two such
historical comparisons that can be made. Hard coral cover has dropped from 23% in 1990
to 9% in 2007, although percentage covers of sponges and algae have remained almost
the same. Few details are given relative to fish species present in the 1990 survey
although the site did have the highest number present among all similar sites surveyed.
On the whole (in general terms), the sites at Shoal Bay – Island Harbour exhibited the
poorest state of health with high fleshy algae and low live coral cover, also with high
levels of sediment cover (albeit this category is combined with turf algae which can be
seen as a beneficial characteristic – see Appendix II). The situation is especially
concerning within the Shoal Bay – Island Harbour Marine Park because it has the highest
complexity values (mean rugosity 49.0, mean relief 14.0) of all the others. This suggests
it used to be an area of high live coral cover, hence the present complexity of the existing
16
(mainly dead) reef areas. If this area is to afford us the coastal protection its reefs have
given Anguilla in the past it is of vital importance that this ‘phase shift’ towards an algae
dominated reef be addressed if at all possible. The factors that cause such a ‘shift’ are
again extremely complex and on the whole poorly understood. Indeed this topic is of
much debate within the scientific community. Generally however it is attributed to a
variety of reasons including (but not limited to): Over-fishing removing grazers and
traps/anchoring damaging the living reef; Diadema autillarum reductions since it’s
1980’s mass mortality event; sea temperature rises increasing mortality from bleaching
events; nutrients input making our coastal waters eutrophic; ocean acidification
interfering with coral physiology; and natural disturbance events increasing in frequency
and severity. Shoal Bay – Island Harbour, being a major tourist hot-spot with many
developments present/under construction (not to mention untold future expansion),
finding a possible solution to at least some of these issues is of utmost significance.
However, it does pose the typical problem of doing so without negatively affecting this
economically important industry. DFMR have begun doing whatever possible to address
these issues with: Diadema antillarum being translocated into the Park from other areas
threatened by destructive coastal development; Establishment of long-term monitoring
sites; the maintenance of mooring buoys to discourage anchoring; reviews of fishery
legislation; and a comprehensive water quality monitoring programme soon to be set up
in collaboration with the water lab. Obviously many of the negative impacts to our ocean
realm have to be dealt with on a regional, if not global, level so are largely out of our
control. However, if those areas that can be addressed locally are to be done so
effectively, it needs the full backing of and support from the Government of Anguilla.
5.0 Conclusions and Recommendations
The sites at Dog Island within this study did not exhibit exceptionally ‘healthy’ habitat
characteristics and so the question is raised as to why it houses such a dense fish
population? It is concluded that these more exposed sites exhibit such characteristics
because they are less likely to be affected by land based ‘pollution’, and are regularly
flushed through (bringing in plenty of food) by strong currents. Similar conclusions can
be drawn when looking at specific sites in detail, as with PP01 which has the second
highest fish density and also relatively ‘healthy’ habitat (although again, like Dog Island,
it does not have high complexity values which are normally associated with higher fish
densities). This site is once more very exposed, being located on the western end of
Prickly Pear West, so currents will regularly flush the area and bring in plenty of food for
primary consumers at the bottom of the food chain and other plankton eaters. These
examples show how reef complexity is not the only, nor the vital, component that
influences fish density, and how important it is to consider each site separately when
drawing in-depth conclusions that will be the building blocks for future management
plans.
The main overall conclusion to be drawn is that in general the healthier habitats are found
further away from mainland Anguilla and the apex of these in the most inaccessible
areas. This fact in itself has management implications, but also presents decisions that fist
17
have to be made: When considering conservational management options should priority
be given to the healthiest sites, and say, make them permanently (or at least seasonally)
closed areas? Or should this happen to the most degraded site in an effort to restore them,
or at least aid their restoration? These questions of course come solely from a fisheries
management perspective, but similar situations present themselves when considering
other (albeit only anthropogenic) causes. For example, Shoal Bay – Island Harbour has
the heaviest tourist usage out of all five Marine Parks (pers. obs.) and Dog Island the
least. Should this be more strictly controlled and potentially effect one of Anguilla’s most
important industries? Another example is highlighted by speculating that nutrient levels
are higher in Shoal Bay – Island Harbour due to land based leaching and/or lower level of
water movement effectively flushing the area on a regular basis. This is an area that
should be looked at in great detail and is indeed part of DFMR’s future work plan.
Below are some recommendations that can be made from the information presented
within this report:
•
•
•
•
•
Special attention should be given to those Marine Parks that are closest to
mainland Anguilla, and the management of these areas enhanced.
An investigation should be made as to whether Dog Island, especially that area
around West Cay, be nominated for special status as an almost pristine region.
Special management should be considered for fish species that are recorded in
lower numbers than historically suggested, for example groupers and jacks.
With a full coastal water quality monitoring programme soon to begin, legislative
support should be given to back up any recommendations made from it. Other
initiatives carried out by DFMR, such as the recent Diadema antillarum
translocations should also be encouraged and supported.
Independent monitoring schemes by developers should be encouraged, as well as
exploring the potential to establish an educational field station that would
facilitate visiting students or researchers to conduct their work in Anguilla.
Endeavors such as these will help build the knowledge base that is currently
lacking which is essential in assisting with in the decision making process that is
needed when pursuing sustainable development.
18
Appendix I – Survey Site Descriptions & Coordinates
Shoal Bay – Island Harbour Marine Park
SB01 (N18 15.584 W063 02.549) – Pavement reef with scattered dead coral heads. Lots of soft corals
and reasonable fish presence. Classed as mixed reef community, low complexity. Shot placed on flat area
close to small sand channel.
SB02 (N18 15.167 W063 02.469) – Same area as AMMP site. Complex dead Acropora palmata stands
in shallow parts (also a couple of live ones), more mixed community on slope into deeper region. Sand
bottom at 18m. Algae dominated on the most part. Classed as mixed reef community, high complexity.
Shot placed in the middle of a partially dead large Montastraea annularis colony.
SB03 (N18 15.723 W063 02.026) – Shallow area with dead Acropora palmata and Proites porites
colonies. In very shallow area it is mostly very bare flattened coral rubble. As site deepens it become more
scattered coral heads with Porites porites fragments scattered around sandy areas. Soft corals also. Classed
as mixed reef community, medium complexity. Shot placed amongst dead Acropora palmata stands, close
to large dead Porites porites structures.
SB04 (N18 15.425 W063 02.110) – Situated near Shoal Bay Reef dive buoy. Quite similar in many ways
to SB02 although less Acropora palmata rubble/dead stands and more algae cover. Shallow but slopes
down to sandy bottom around 18m. Some fish diversity but abundance seems low. Classed as algae
dominated mixed reef community, high complexity. Shot placed in approximately 5m of water among
rubble and soft corals.
SB05 (N18 15.854 W063 01.499) – Situated near Lobster Reef dive buoy. Small slope from shallows
into deeper water made up of rubble from various coral species. Resembles a grave yard somewhat with
low live hard coral cover. Some soft corals. Fish diversity & abundance seemed low. Classed as mixed reef
community, medium complexity. Shot placed in small sand/rubble patch surrounded by soft corals.
SB06 (N18 15.572 W063 01.604) – Same area as AMMP sub-site (to become site in it’s own right when
more are added to the AMMP project). Reef slopes from shallows (mainly consisting of Porites porites &
Montastraea annularis colonies – both alive and dead) down to 19m sandy bottom. Many fish swimming
(Snappers, Sergeant Majors, Parrotfishes, Grunts, Chromis) off slope over deeper water. Down slope coral
diversity increases (both hard & soft) although much is dead and algae predominates. Classed as algae
dominated mixed reef community, medium – high complexity. Shot placed in 5m of water on Porites
porites rubble.
SB07 (N18 15.752 W063 01.314) – Similar in many ways to SB06, although here in shallows many dead
Acropora palmata stands predominate, and slope down to sandy bottom is only 12m. Very low fish
diversity and high algae cover. Many soft corals and intrusive fish/crayfish traps. Classed as algae
dominated mixed reef community, medium – high complexity. Shot placed in small sand patch surrounded
by dead coral heads.
SB08 (N18 15.497 W063 01.034) – Located inshore between Shoal Bay East (Upper) and Island
Harbour. Large patch reefs, with this site being located on the northern edge of one. Shallow reef (3m with
some structures breaching surface) that gradually slopes down to sandy bottom at 12m in parts, although
sandy areas are shallower in parts. Algae dominated with not much live hard coral. Soft corals quite
abundant. Fish diversity and abundance reasonable with large parrotfish common. Classed as Algae
dominated mixed reef community, medium to high complexity. Shot placed on flat area near large
Montastraea annularis colony.
19
SB09 (N18 16.017 W063 00.110) – Inner side of outer reef area north of Scilly Cay. Generally flat with
small – medium old coral heads of mixed species. Small sand patches. Lots of small soft corals suggesting
past mortality event. Fish abundance high if considering smaller species, although a few parrotfish were
present. Similar in many ways to SB01. Algae present in quantity but not as dominant as at other sites.
Classed as mixed reef community, low complexity. Shot placed in bare area close to one of the larger small
sand patches.
SB10 (N18 15.798 W063 00.224) – Outer side of inner reef slightly west of Scilly Cay. Steep reef slope
(made mainly from dead and broken Acropora palmata stands – in shallows some still survives) from 2m
shallows drops to sandy bottom at 9m. Sandy bottom has scattering of coral structures/rock. Heavy algae
growth and little live hard coral apparent. Quite an abundance of reasonable sized Parrotfish. Good variety
of soft corals. Classed as algae dominated mixed reef community of high complexity. Shot placed in
around 5m of water on slope (about 100m east of submerged pedal boat).
SB11 (N18 15.898 W062 59.873) – Outer side of inner reed slightly east of Scilly Cay. Shallow area (25m) of pavement reef with some raised topology. Large numbers of soft corals, but also small hard coral
colonies present. Some small dead Acropora palmata stands, although a few patches are still alive. Fire
coral appeared common. Lots of small juvenile fish noted, with a scattering of large parrotfish too. Algae
not dominant. Classed as a mixed reef community of low complexity. Shot placed close to raised topology,
with flatter region to the north.
SB12 (N18 15.828 W062 59.723) - Located on end of reef that stretches past back of Scilly Cay.
Complex Acropora palmata stands/rubble. Shallow in parts but slopes down to c.8m deep sand/rubble
region. Algae dominated reef with low live hard coral cover and limited soft corals. Fish diversity and
abundance low although a few large Parrotfish were noted. This area seems somewhat ecologically dead
although it is classed as algae dominated mixed reef community, high complexity. Shot placed on coral
rubble at c4m.
Little Bay Marine Park
LB01 (N18 13.641 W063 04.216) - Located around AMMP site in eastern side of Marine Park. Sea
grass, with mixed Halimeda and saucer blade algae. All fish sighted were small/juveniles. Approximately
6m in depth. Numerous small sand hills and a couple of bare sand patches present. Classed as seagrass bed.
Shot placed in small sand patch.
LB02 (N18 13.572 W063 04.379) - Located around AMMP site in central part of Marine Park. Sea grass,
with mixed Halimeda and saucer blade algae. All fish sighted were small/juveniles. Approximately 8.5m in
depth. Numerous small sand hills present. Site situated closer to some larger sandy areas than other sites at
Little Bay. Classed as seagrass bed. Shot placed in small sand patch.
LB03 (N18 13.452 W063 04.340) - Located in western side of Marine Park. Sea grass, with mixed
Halimeda and saucer blade algae. All fish sighted were small/juveniles. Approximately 8m in depth.
Numerous small sand hill and some bare sand patches present, some larger than others. Classed as seagrass
bed. Shot placed in small sand patch.
Sandy Island Marine Park
SA01 (N18 12.773 W063 07.588) – Located close to the small cay NW of Sandy Island. 4 – 7 meters in
depth with sandy/rubble bottom dominated by soft corals (some hard corals present – mainly Mustard Hill
although noticed a bit of Staghorn). Mainly juvenile fish (lots of small blue headed wrasse), surgeonfish
and parrotfish. Classed as soft coral dominated mixed reef community of low complexity. Shot placed in
sand patch near slightly raised area with dead coral heads and lots of soft corals (mainly Sea Plumes)
housing a huge shoal of French Grunts.
20
SA02 (N18 12.549 W063 07.481) – Located southwest of Sandy Island. This site is very similar to SA01
although some patches of soft corals seemed rather denser here. Fish assemblage seemed similar also
although no large schools of French Grunts noted. Classed as soft coral dominated mixed reef community
of low complexity. Shot placed in sand patch near dense soft coral area (mainly Sea Plumes).
SA03 (N18 12.841 W063 07.148) – Located on eastern side of reef around sandy island quite close to
ship wreck. Highest amount of hard coral seen to date with huge finger coral colonies and good sized
Montastraea sp. Also Staghorn colonies present which are rare around Anguilla. Some sandier areas and
also some areas that appear fairly barren/dead. Some algae but patchy. Hundreds of Chromis noted. Classed
as hard coral dominated mixed reef community of medium complexity. Shot placed in sand/silt depression
in middle of a huge finger coral colony.
SA04 (N18 12.850 W063 06.934) – Located east of site SA03. Sand channels with ridges of hard corals
(dead Acropora palmata etc). Gradual slope into a sandy bottom at around 10m. Reasonably abundant soft
corals, with live hard coral being quite sparse. Moderate fish abundance and diversity. Class as mixed reef
community of medium complexity. Shot placed in one of the sand channels.
Prickly Pear Marine Park
PP01 (N18 15.995 W063 11.403) – Located on southwestern side of Prickly Pear West, comprising a
small ridge with interspersed sand holes. Not much hard coral cover but many brightly coloured sponges
and also lots of small soft corals. Good fish diversity with both small juveniles and larger individuals
(Barracuda, French Grunts etc). Hundreds of Bluehead wrasse. Also sighted a Hawksbill Turtle. Depth
between 5 – 10 meters (although more shallow areas present near sea rocks). Not algae dominated. Classed
as mixed reef community of low complexity. Shot placed on flat area on top of the ridge.
PP02 (N18 16.290 W063 10.567) – Located on northern side of Prickly Pear East in inner area of outer
reef. Many large coral heads with small sand patches or lower relief hard bottom. Large Montastraea
annularis colonies present in mixed states of health – some mostly dead. Also areas of Acropora palmata
rubble – a few colonies alive. Limited soft corals present. Fish diversity and abundance moderate. Some
algae growth, but hard to say if it is dominant. Classed as mixed reef community of medium/high
complexity. Shot placed in small sand patch surrounded by (mainly dead) coral colonies.
PP03 (N18 15.718 W063 10.070) – Located on eastern end of Prickly Pear East. Shallow region near
rocks comprised of sandy bottom with quite dense scattering of coral colonies/heads. Good diversity of fish
present with both juveniles and adults (especially Parrotfish). Depth 3 – 7 meters. Not algae dominated.
Classed mixed reef community of medium complexity. Shot placed on sand patch amongst coral heads.
PP04 (N18 16.156 W063 08.891) – Located midway along northern coast of Seal Island. Flat pavement
reef with scattered, mostly algae covered, old coral heads. Also some patches of dead Acropora palmata
and some small canyons. Many Grunts, Tangs and Parrotfish around this rubble. Site slopes up towards sea
rocks to the south, with gradual slope down into deeper water to the north. Few soft corals, but still classed
as mixed (pavement) reef community of low/medium complexity. Shot placed amongst area of coral
rubble.
PP05 (N18 15.934 W063 08.194) – Located past east of southern coast of Seal Island (Inner west of
Long Reef). Gently sloping reef comprised mainly of low topology Montastraea annularis colonies
(mostly dead) interspersed among sandy/hard bottom with some algae cover. Shallow areas (3m) slowly
slope down to sandy bottom at around 10m, although the actual survey site only varies between 5 – 8.5
meters in depth. Mostly juvenile fish notes. Some soft coral and algae cover. Relatively high numbers of
Hamlets and many Three Spot Damselfishes (Stegastes planifrons) present. Classed as mixed reef
community of medium complexity. Shot placed among dead coral colonies at c6m.
21
PP06 (N18 15.741 W063 07.513) – Located almost midway along Long Reef (Inner). Very similar to
PP05 although the gently sloping reef comprised mainly of Montastraea annularis colonies (mostly dead)
has slightly higher topological complexity with less sandy/hard bottom areas. Also seems to have a better
diversity of hard corals (some Staghorn (Acropora cervicornis) for example). Shallow areas (3m) slowly
slope down to sandy bottom at around 10m, although the actual survey site only varies between 6 – 8.5
meters in depth. Mostly juvenile fish notes. Some soft coral and algae cover. Relatively high numbers of
Hamlets and many Three Spot Damselfishes (Stegastes planifrons) present. Classed as mixed reef
community of medium complexity. Shot placed in small sand hole at c7m.
PP07 (N18 16.222 W063 06.269) – Located along Long Reef, towards it’s eastern end pretty close to the
MV Sarah wreck. Some shallow areas of dead Acropora palmata, but some living colonies present also.
Also large colonies of Porites porites and Montastraea sp with finger coral being dominant. Other live hard
corals present – probably the highest percentage cover of all sites studies. Some scattered sand patches and
a good abundance and diversity of fish. A very pretty survey site. Classed as a hard coral dominated mixed
reef community of medium/high complexity. Shot placed in small sand hole near a large Montastraea sp
colony.
PP08 (N18 16.150 W063 05.525) – Located on the far western outer end of Long Reef. Shallow (3m)
area with slope down to rocky/coral/sand plateau at 10m. Many dead, but also a number live, Acropora
palmata colonies. Many White Encrusting Zoanthids (Palythoa caribaeorum) present in shallower regions.
Strong current present. Good fish diversity, low levels of algae and some soft corals. Classed as mixed reef
community of high complexity. Shot places among dead coral colonies (midway down slope).
Dog Island Marine Park
DG01 (N18 16.526 W063 14.559) - Located midway along the southeastern coast of the island.
Generally this region consists of pavement reef with scattered algae and the odd small ridge or small rock.
The location of this site was the same as this although it had more topological features than the immediate
surrounding area – such as a few small (20cm deep) ledges housing many lobsters; and a scattering of some
small rocks. For such low complexity this site had an abundance of fish – mainly grunts, goatfish,
surgeonfish and (interestingly) black bar solider fish. Classed as an algal pavement reef of low complexity.
Shot placed in small rubble covered depression surrounded by small ledges.
DG02 (N18 16.650 W063 16.392) – Located on the northeastern coast of West Cay. A very
topologically complex region with limited hard coral but many brightly coloured sponges. Some areas of
densely packed soft corals. Topology is not ‘complex’ here like mounds of Acropora palmata are for
example, rather highly three dimensional with tall rock peaks and trenches resembling a mountain range.
High fish diversity and abundance with many Black Durgeons, Grunts and Bar Jacks. Classed as a mixed
reef community of high complexity. Shot placed on top of a small plateau amidst the ‘mountains’.
DG03 (N18 17.142 W063 15.616) – Located near the southeastern coast of Mid Cay. A flat pavement
area slopes up and becomes covered in low lying hard corals (mixture of dead & alive). As this slope
gradually reaches it peak soft corals become more dominant. The peak then dips sea ward gradually into
the deep – this area is soft coral dominated. A good diversity and abundance of fish present. Classed as
mixed reef community of medium complexity. Shot placed in sand hole amongst the low lying hard corals
just prior to the slope peaking. It should be noted that on the relatively calm day this exposed site was
surveyed quite a strong current was present making work more difficult.
**See following page for a map illustrating the locations of these study sites**
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Appendix II – Notes on Data Analysis and Limitations
Occurrence Categories (RDT)
Based on overall density if extrapolated into numbers seen per hectare of representative
habitat, where <1ha-1 is considered ‘rare’, <10 ha-1 ‘Uncommon’, <150 ha-1 ‘Occasional’,
<750 ha-1 ‘Common’ and >750 ha-1 is ‘abundant’. These categories do not take into
account specifics of any particular species’ life history traits (i.e. being cryptic and
therefore problematic to accurately survey), nor are the categories based on prior research
as to what should be considered, for example, an abundantly occurring species. The
categories are merely a tool used within this report to provide qualitative results for a
species’ abundance, where in the results section the ‘most commonly occurring species’
are those that fall into the category of ‘abundant’. These categories also relate to hectares
of representative habitat and are not realistic when considering variations that can occur a
short distance away from a site. Hectares were used rather than square meters in order to
emphasize differences between sites. The exact figures that resulted from the RDT
surveys should be used for more detailed future analysis, although again any particular
species’ life history traits should be considered when drawing any conclusions. For
example many Damselfish (Pomacentridae) are often cryptic as are most Blennies
(Labrisomidae, Chaenopsidae, Blenniidae & Tripterygiidae) and Gobies (Gobiidae). In
many of these cases a mere presence/absence can be concluded rather than an accurate
abundance/density. It should also be noted that species were placed into different
abundance categories when submitting data to REEF depending on their tally per survey
conducted where: 1 = ‘one’, 2 – 10 = ‘few’, 11 – 100 = ‘many’, and >100 = ‘abundant’.
Relative Abundance (SPC)
Results were only worked out to a relative abundance value (individuals survey-1)
because in the methodology fish were counted within a five meter radius of the surveyor,
thus forming a sphere. Within this sphere, especially on sites that were characterized by a
steep slope, there might be a variety of habitats, including open water. For this reason it
was felt more appropriate to leave abundance relative. As it turns out most of these
figures were not used in the discussion section so this point is largely academic.
Underlying substrate categories (Habitat)
For the purpose of this project the underlying substrate was split into three categories
defined as: Solid – Rock or other consolidated hard material that does not move readily;
Rubble – Loose hard material ranging in size from pebbles to small boulders, although
they must be potentially movable (i.e. could shift location in a storm); and Sand – as
described. When categorizing the substrate the surveyor was encouraged to make
investigations to find out, for example, if sand was only a light covering over rock, and so
underlying substrate should therefore be classed as Solid. For this reason, and also due to
plants/algae overgrowing sand, the percentage cover in the underlying substrate section
may differ greatly to that in the sand percentage cover when making biotic/barren
assessment.
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Biotic or Barren (Habitat)
These categories of the habitat relate to the percentage cover of either flora, fauna or
barren (sand, sediment) characteristics over the underlying substrate. Initially a category
existed for bare rock, but as none was seen during surveys this was later disregarded.
Although rock can look bare a lot of the time it invariably is covered with either
sediment, turf algae, coralline algae or a mixture. Turf algae rarely exists on its own and
is usually accompanied with a dusting of sediment (sometimes a very heavy dusting),
hence why these two characteristics were grouped together. Coralline algae usually has a
covering of turf algae too, a fact that should be noted when considering the results from
this habitat work.
Note on depth limitation (General)
Because of replicate number surveys were not carried out in water deeper than ten
meters. With fewer logistical constraints it would have been more favorable to specify a
depth for a certain number of survey replicates (i.e. 5m, 10m & 15m – habitat
permitting). With the resources available it was felt advantageous to specify a depth
range for all surveys, but record the depth of each survey for use in later analysis.
Definition of ‘Health’ (General)
This term is used in a general sense throughout this project, and is a qualitative measure
rather than quantative. For example, a site with high fish density and/or diversity may be
described as having a healthy fish population, although this may not necessarily be the
case (i.e. the dense population may be caused by a large school of Jacks passing through
and so not represent a high resident population). The term is also used when referring to
habitat, and is based loosely on high coral cover and low fleshy algae. Sediment may also
be seen as a negative characteristic, but high complexity (rugosity & relief) a positive
one. When the term has been used it is not based on any calculations or index of health
and so is used again in a qualitative sense. More detailed analysis may come to different
conclusions than have been drawn here regarding which sites were in fact the most
‘healthy’.
Variation of habitat types between study sites within Marine Parks (General)
For the most part of this report sites within each Marine Park are grouped together and
talked about in general terms. However, sites often varied greatly within each park and so
this grouping is not necessarily correct. For example, SB01 was flat pavement type reef at
a relatively constant depth with scattered coral colonies and soft corals where as SB02
was a more complex region sloping from 2m down to a depth of more that 15m, where it
then developed a sandy bottom. The reason sites have been grouped like this is because
of the general nature of this report, but when conducting a more detailed analysis it would
be an incorrect thing to do. This is the main reason for including site descriptions in
Appendix I, so that grouping can be made based on similar habitat
characteristics/geographic location. This document only represents a ‘report’ on work
conducted and brief discussion and is not meant to form the basis of management
decisions unless accompanied by a more detailed analysis and socioeconomic
assessments.
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Survey Numbers within Marine Parks (General)Each park had a varying number of
study sites, the amounts of which were chosen as described in the methods section.
However, although this was a wise thing to do for the most part, some artifacts may be
produced in the dataset as a result. For example, during the RDT surveys the number of
species recorded in a park as whole is likely to be higher if more sites are visited due to
the increased likelihood of sighting less common species. For a more realistic result each
park was given a diversity value based on the mean number of species seen within each
site across the park as a whole. It should be noted here that an actual diversity index was
not used in this report, which might prove beneficial if conducting a more detailed
analysis.
Data Inconsistencies (General)
Density discrepancies between the RDT surveys and SPC surveys such as that seen in
PP04. Reasons for this are unclear but are likely due to a mixture of reasons. For
example, the survey types look at different groupings of fish, so a higher RDT result than
SPC is likely caused by a huge school of fish not recorded using the SPC methodology,
for example, Wrasse (Labridae) or Chromis sp. In cases where SPC yields higher results
than RDT, the most likely scenario is caused by a school of fish, for example, Acanthurus
sp., swimming past the surveyor and not being sighted by the RDT surveyor. This latter
scenario would likely be solved by increasing survey replicate number. However, there
are other possible reasons that could be due to data handling/analysis. For example,
results from RDT & SPC methods may yield more similar results if both were split into
the same categories (i.e. RDT results grouped into fish families as SPC results were).
Another possible reason for this later discrepancy that would not be solved by increasing
replicate number would be double counting individuals. This is far more likely to happen
when using the SPC methodology than it is with RDT surveys because rather than
remaining in the same spot you swim over new habitat at all times. For this reason when
discussing results in this report SPC data are on the whole only used for size class
distributions (if double counting did occur then it is assumed it will be uniform across all
size classes and so not affect the distribution curve), and RDT data for density and
diversity purposes. On a few occasions however they are mentioned because they
highlight an interesting issue. It is not suggested that any future, more detailed statistical
analysis, should follow this course as it is probable that there are extremely valid and
correct reasons for this inconsistency, however, for the purpose of this report this is the
decision that was made.
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Appendix III – Example Datasheets: Roving diver datasheet (this page); Fish
size class datasheet (second page following); Habitat quadrat datasheet (third page
following).
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References
Bythell J. (1995). The Anguillian Marine Resources Atlas. Natural Resources Institute,
University of Greenwich, Kent, UK.
Humann P. & Deloach N. (1989). ‘The Reef Set’. New World Publications.
Oxenford H.A. & Hunte W. (1990). ‘A survey of marine habitats around Anguilla, with
baseline community descriptors for coral reefs and seagrass beds’. Report for the
Department of Agriculture and Fisheries, Government of Anguilla, 177 pages.
Wynne S.P. & Côté I.M. (2007). ‘Effects of habitat quality and fishing on Caribbean
spotted spiny lobster populations’. Journal of Applied Ecology 44. p.488 – 494.
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