coastal conservation project an assessment of the coral reefs of

Transcription

COASTAL CONSERVATION PROJECT
AN ASSESSMENT OF THE
CORAL REEFS OF
TOBAGO
Prepared by
Kahlil Hassanali
September 2009
INSTITUTE OF MARINE AFFAIRS
RESEARCH REPORT
COASTAL CONSERVATION PROJECT
AN ASSESSMENT OF THE
CORAL REEFS OF
TOBAGO
Prepared by
Kahlil Hassanali
Jr. Research Officer
September 2009
Institute of Marine Affairs
Hilltop Lane, Chaguaramas
P.O. Box 3160, Carenage Post Office
Trinidad and Tobago, W.I.
Tel. (868) 634-4291-4
Fax. (868) 634-4433
Email: [email protected]
i
ABSTRACT
In 2004, while preparing the State of the Marine Environment Report, it became apparent
that there was a lack of recent information on the state of reefs in Tobago except for
Buccoo Reef which has been monitored under the CARICOMP project. In addition,
there were many requests from the public for information on the state of reefs. This
project sought to bridge this knowledge gap and entailed a re-surveying of reefs at
Buccoo, Culloden, Arnos Vale and Speyside. Surveys were also conducted at La Guira
Bay.
Results from the assessment of the various areas around Tobago showed the fates of reefs
to be mixed in terms of comparative extent of hard coral cover over the last two and a
half decades. Mean hard coral declines were seen in some areas e.g. Buccoo and
Culloden, whereas improvements were observed in others e.g. Arnos Vale and Speyside
Reefs. Reefs in Man-o-War Bay, showed no overall trend with slight improvements in
mean hard coral cover at the mid and lower fore reef zones while there was a large
reduction in cover at the upper fore reefs. Surveys carried out at the reefs in La Guira Bay
were novel and thus comparisons could not be made. However, macroalgae cover is of
major concern especially at the Cove Ledge dive site.
Coral bleaching was not observed during surveys which was not surprising as they were
not conducted during an ‘El Niño’ period. However, high incidence of yellow band
disease was observed especially on the Buccoo and Culloden Reefs. Also, the rapid
assessment method revealed that Diadema antillarum numbers remain low compared to
pre die off density estimates.
ii
TABLE OF CONTENT
Page
ABSTRACT
i
1.0
INTRODUCTION
1
2.0
METHODOLOGY
8
3.0
RESULTS
19
3.1
ARNOS VALE
19
3.2
BUCCOO
23
3.3
CULLODEN
33
3.4
MAN-O-WAR BAY
43
3.5
SPEYSIDE
50
3.6
LA GUIRA BAY
60
3.7
RAPID ASSESSMENT
68
4.0
DISCUSSION
69
5.0
CONCLUSIONS
78
6.0
REFERENCES
80
7.0
ACKNOWLEDGEMENTS
83
iii
LIST OF FIGURES
Page
Figure 2.1:
Map of Tobago
8
Figure 2.2:
Map of Arnos Vale Reef showing general location of
survey sites
10
Figure 2.3:
Map of Buccoo Reef showing general location of survey
sites
11
Figure 2.4:
Map of Culloden Bay showing general location of survey
sites
12
Figure 2.5:
Map of Man-o-War Reef showing general location of
survey sites
13
Figure 2.6:
Map of La Guira Bay showing general location of survey
sites
14
Figure 2.7:
Map of Speyside Reef showing general location of survey
sites
15
Figure 2.8:
Species recovery curves for eight photoquadrats at 9m
Culloden West (Site A) and 16m Buccoo Western Reef
(Site B).
17
Figure 4.1:
Hard coral cover comparisons between the Laydoo (1985
a-e) surveys and the current assessments
70
iv
LIST OF TABLES
Page
Table 1.1:
Number of species found in varying benthic categories in
surveys of Tobago’s reefs (excluding those done by Laydoo,
1985 a-e).
3
Table 1.2:
Number of species found in varying benthic categories in
Laydoo (1985 a-e) surveys of Tobago’s reefs.
4
Table 2.1:
Depths surveyed at the various sampling sites located in the
different reef areas studied around Tobago. Number of survey
depths was dependent upon the fore-reef slope structure at the
sites.
9
Table 3.1.1:
Species cover on reef crest (3m) at Arnos Vale survey site.
19
Table 3.1.2:
Species mean density and frequency on reef crest (3m) at
Arnos Vale survey site.
20
Table 3.1.3:
Species cover on the upper fore reef (9m) at Arnos Vale
survey sites.
21
Table 3.1.4:
Species mean density and frequency on the upper fore reef
(9m) at Arnos Vale survey sites.
22
Table 3.2.1:
Species cover on the reef crest (3m) at Buccoo survey sites.
24
Table 3.2.2:
Species mean density and frequency on the reef crest (3m) at
Buccoo survey sites.
25
Table 3.2.3:
Species cover on the upper fore reef (9m) at Buccoo survey
sites.
26
Table 3.2.4:
(9m) at Buccoo survey sites.
28
Table 3.2.5:
Species cover on the mid fore reef (16m) at Buccoo survey
sites
29
Table 3.2.6:
Species mean density and frequency on the mid fore reef
(16m) at Buccoo survey sites
30
Table 3.2.7:
Species cover on the lower fore reef (21m) at Buccoo survey
sites
31
v
LIST OF TABLES
Page
Table 3.2.8:
Species mean density and frequency on the lower fore reef
(21m) at Buccoo survey sites.
32
Table 3.3.1:
Species cover on the reef crest (3m) at Culloden survey site
34
Table 3.3.2:
Culloden survey site.
35
Table 3.3.3:
Species cover on the upper fore reef (9m) at Culloden survey
sites.
36
Table 3.3.4:
(9m) at Culloden survey sites
37
Table 3.3.5:
Species cover on the mid fore reef (16m) at Culloden survey
sites.
39
Table 3.3.6:
(16m) at Culloden survey sites
40
Table 3.3.7:
Species cover on the lower fore reef (21m) at Culloden
survey site.
41
Table 3.3.8:
(21m) at Culloden survey site
42
Table 3.4.1:
Species cover on the reef crest (3m) at the Man-o-War Bay
survey sites
44
Table 3.4.2:
Man-o-War Bay survey sites
45
Table 3.4.3:
Species cover on the upper fore reef (9m) at Man-o-War Bay
survey sites
47
vi
LIST OF TABLES
Page
Table 3.4.4:
(9m) at Man-o-War Bay survey sites
48
Table 3.4.5:
Species cover on the mid fore reef (16m) at Man-o-War Bay
survey site
49
Table 3.4.6:
(16m) at Man-o-War Bay survey site
49
Table 3.4.7:
Species cover on the lower fore reef (21m) at Man-o-War
Bay survey site
50
Table 3.4.8:
(21m) at Man-o-War Bay survey site
50
Table 3.5.1:
Species cover on the reef crest (3m) at Angel Reef, Speyside
survey sites
52
Table 3.5.2:
Angel Reef, Speyside survey sites
53
Table 3.5.3:
Species cover on the upper fore reef (9m) at Angel Reef,
Speyside survey sites
54
Table 3.5.4:
(9m) at Angel Reef, Speyside survey sites
55
Table 3.5.5:
Species cover on the mid fore reef (16m) at Angel Reef,
57
Table 3.5.6:
58
Table 3.5.7:
Species cover on the lower fore reef (21m) at Angel Reef,
59
vii
LIST OF TABLES
Page
Table 3.5.8:
60
Table 3.6.1:
Species cover on the upper fore reef (9m) at Cove Ledge, La
Guira survey sites
62
Table 3.6.2:
Species cover on the upper fore reef (9m) at Majeston, La
Guira survey sites
63
Table 3.6.3:
(9m) at the Cove Ledge and Majeston, La Guira Bay
64
Table 3.6.4:
Species cover on the upper fore reef (9m) at Flying Reef, La
Guira Bay
66
Table 3.6.5:
(9m) at Flying Reef, La Guira survey
67
Table 4.1:
Siderastrea siderea percentage cover change between the
Laydoo (1985 a,b,c,e) surveys and the present surveys
76
LIST OF PLATES
Page
Plate 2.1:
Photoquadrat from 16m depth at Western Reef, Buccoo
viii
16
1.0
INTRODUCTION
Coral reefs are an integral part of the Caribbean environment, providing over 100 million
people in more than 25 countries and territories with food, coastal protection, and
revenue from tourism (Population Reference Bureau 1996). Tourism is the region’s most
important economic sector, and reefs provide much of the sand for the region’s beaches,
where most tourists spend their time (Burke & Maidens 2004). Tourist arrivals to the
Caribbean were estimated at nearly 28 million in 1999 (Caribbean Tourism Organisation
2001) and tourism revenue alone brings in over US $25 billion a year to the region
(Burke & Maidens 2004).
In spite of their importance, Caribbean coral reefs are under severe pressure mainly from
human activities such as coastal development, land clearance and intensive agriculture
among others (Mora 2008). In addition to this, there are impacts from global phenomena
such as climate change (Johannes 1970; Rogers 1985, 1990; Woodley 1992; Glynn 1997;
UNEP 2002). Thus, seventy-five percent of Caribbean reefs are in serious decline or
under threat (Hinrichsen 1996). There has been a major loss of coral cover and diversity
(Hoegh-Guldberg 1999; Wilkinson 2000; Gardner et al. 2003), coupled in many areas
with an increase in algal biomass and shift in algal community structure (Littler et al.
1992; Lapointe 1997; Hughes 1994).
Tobago reefs are not exempt from these deleterious impacts and changes. However, the
extent to which they are being affected is not quite known. Most studies on coral reefs
here have concentrated on the Buccoo and Speyside Reef ecosystems. Reefs at Man-OWar Bay, Culloden and Arnos Vale have also received some attention.
Buccoo Reef, designated a marine protected area (MPA) in 1973 and with its long history
of being one of Tobago’s major tourist attractions, is the most studied reef system in
Tobago. Goreau (1967) carried out largely qualitative work within the context of
potential impacts on the reef from planned tourist development on the south-western
1
coast of the island. Aerial and underwater observations were made of the reef, the latter
being done on the eastern side of the ecosystem noting general floral and faunal zonation
and species diversity patterns. Bon Accord Lagoon and associated mangrove habitat was
also similarly observed. Goreau commented and speculated upon the trophic relationships
amongst and between the Buccoo Reef-Bon Accord Lagoon complex noting the close
interdependence between the reef and mangrove lagoon, and actually considering them as
a single ecological unit. Recommendations were also made for the preservation of the
entire wetland ecosystem in the face of what was then proposed development. These
included the creation of a marine park and initiating long term study on the ecology of the
Buccoo area with particular reference to the mangroves and reefs.
Several years later Kenny (1976) conducted a preliminary study of the Buccoo Reef/Bon
Accord complex in response to the general question of development and management of
coastal resources. This preliminary study entailed a hydrographic survey with a view to
producing an up-dated map of the reef and lagoon, a faunal assessment so that a
comprehensive species list could be made and lastly, a delineation of the extent of
damage to the reef.
In the purely qualitative damage assessment it was found that, generally speaking, the
seaward slopes and the reef crest, excluding the tourist area, were only slightly damaged.
Damages observed in these areas were attributed to natural causes and more specifically
storm surge. The tourist area (the reef crest and back reef of Outer Reef) however, was
extensively damaged although, due to compounding historical data, it was uncertain
whether the damage here was caused by human activity. Kenny did suggest that storms
initially damaged the tourist area and subsequent activity on the reef prevented the
natural regeneration that might be expected.
With regards to the flora and fauna of the reef and lagoon Kenny (1976) concluded that
compared with other reefs in Tobago, Buccoo Reef is somewhat impoverished. He cited
sub-oceanic conditions e.g. low salinity during the rainy season, high turbidity and high
2
turbulence, as being possible reasons for this. His investigations yielded 1 sponge
species, 2 hydrozoans, 21 hexacoral species and 8 octocoral species (Table 1.1).
Table 1.1: Number of species found in varying benthic categories in surveys of Tobago’s
reefs (excluding those done by Laydoo, 1985a-e)
BENTHIC CATEGORY
Reef Location
Study Author
Sponges
Hydrozoans
Octocorals
Zoanthids
Hexacorals
Black Corals
Man-O-War Bay
Ramsaroop (1981)
4* (4)
3
21
2
24
2* (2)
Buccoo Reef
Kenny (1976)
1* (1)
2
8
2
21
undetermined
Speyside
IMA (2002)
3* (2)
2
9* (6)
1
26
undetermined
*
(#)
- no. undetermined at species level
Laydoo’s (1985a) benthic species number counts on Buccoo Reef (Table 1.2) differ
slightly from those reported by Kenny (1976). The former surveys at different reef sites
throughout Tobago however, did validate claims by the latter that benthic species number
in Buccoo is less than most other reef areas in Tobago. The mapping and benthic
sampling studies done by Laydoo remain today the most comprehensive quantitative
survey ever carried out on the Buccoo Reef ecosystem, gathering information on mean
species cover (% m-2), mean density (col. m-2) and frequency of occurrence (%) of the
benthic community.
In the aforementioned ecological surveys, the authors all highlighted the need to monitor,
assess and mitigate the impacts of sewage pollution and land run-off. Little quantitative
work was done until Lapointe et al. (2003) who did provide actual evidence of sewage
driven eutrophication in the Buccoo Reef Complex (BRC). Laydoo and Heileman (1987)
in a study of the environmental impacts of sewage treatment plants in Buccoo and Bon
Accord did find that improperly functioning plants exhibited direct impacts on the quality
of the downstream and receiving marine environment, including the BRC.
3
Table 1.2:
Number of species found in varying benthic categories in Laydoo (1985a-e)
surveys of Tobago’s reefs
BENTHIC CATEGORY
Reef Location
Algae
3*
(3)
Speyside
4*
(4)
Man-O-War Bay
3* (3)
Buccoo Reef
Culloden
Arnos Vale
1*
(1)
2*
(2)
Sponges
2*
(2)
Hydrozoans
Octocorals
Zoanthids
Hexacorals
Black Corals
3
14
1
21
1
1**
4*
(1)
16
2
24
2* (1)
4* (4)
5* (2)
19
3
27
3
(undet.)
4
16
1
27
0
13
1
20
0
3*
(3)
3*
(1)
(#)
* - no. undetermined at species level
** - distinguished up to level of class
Several years later Lapointe et al. (2003) reported that dissolved inorganic nitrogen
(DIN) and chlorophyll-a within the BRC were high compared to other fringing reefs
around Tobago and were indicative of eutrophication. In addition, values for δ15N ratios
(= 15N/14N) for macroalgae in the BRC were within the range reported for those growing
on sewage nitrogen. They alluded to the fact that relatively low cover of hermatypic
corals and high cover of macroalgae, turf algae, octocorals and Palythoa was evidence of
cumulative impacts of land based nutrient enrichment.
Two extensive surveys were conducted on the reefs in Speyside, the first being Laydoo
(1985e) and the second by IMA (2002). Laydoo’s study – a preliminary investigation of
the nature and distribution of the reefs at Speyside – found that species distribution and
abundance appeared to be related to the structural zonation of the reefs. Hydrozoans and
zoanthids were common on the shallow reef flats, octocorals and stony corals dominant
on the fore reef slopes and black corals and sponges abundant on the lower fore reef
areas. In total 48 species of hydrozoans, octocorals, zoanthids, stony corals and black
corals were recorded in his surveys (Table 1.2).
IMA (2002) also found scleractinians, gorgonians and sponges to be the dominant
organisms observed on the reefs. This study, which also incorporated physical
oceanography, water and sediment quality and microbiological analysis with the
biological/ecological components found that cover of live substrate did not change
4
significantly since the Laydoo 1985 survey. However, many diseased corals were
observed, especially the reef building corals – Montastrea annularis, Siderastrea siderea
and Diploria strigosa. Infection in corals was observed at all depths. In addition to this
the population of Diadema was still low following mass mortality that occurred region
wide (Lessios et al. 1984, Laydoo 1985 f). Algal mats observed covering dead corals at
Big Reef and Lucy Vale Reef in the Speyside area were most likely a sign of the strained
populations.
Along with Buccoo and Speyside, the nature and distribution of reefs at Man-O-War Bay,
Culloden Bay and Arnos Vale was also determined by Laydoo (1985b-d). The coral reefs
in Man-O-War Bay were previously surveyed by Ramsaroop (1981). He carried out
observations and identified benthic inhabitants at Booby Island Reef, Rest House Reef
and Pirate’s Bay Reef. No quantitative investigations were carried out, but an idea of
species number in varying benthic classes and sub classes was ascertained (Table 1.1).
Although, reefs at Man-O-War Bay lack lagoons - which suggest that these reefs are
younger than the Buccoo Reef - Ramsaroop postulated that being further removed from
the effects of the Orinoco River effluent, especially lower salinity and higher turbidity
levels, allowed reefs at Man-O-War to be more species rich than the Buccoo Reef. Both
he and Laydoo (1985b) endorsed the huge potential, especially of Rest House and
Turpin’s Reef, for marine tourism, due to their accessibility. They did stress however,
that this characteristic could also prove disadvantageous if proper conservation
precautions were not taken.
Man-O-War Bay reefs were impacted by the mortality of Diadema antillarum which was
first officially documented on Tobago’s reefs in March 1984 at Man-O-War’s Booby reef
(Laydoo 1985f). Pre-mortality estimates here were approximately five (5) urchins.m -2.
As alluded to earlier, this mass mortality was a region wide phenomenon in the
Caribbean (Lessios et al. 1984) with all reefs in Tobago eventually being affected.
Surveys at Culloden Bay, on Tobago’s leeward coast, indicated that the reef system was
in a youthful and vigorous stage of development (Laydoo 1985c). This was inferred
5
through the presence of a diverse benthic fauna (Table 1.2) and more so, a ‘spur and
groove’ fore-reef morphology. The reef comprised of numerous sediment channels, at
right angles to the coastline, separated by buttresses made of mainly large, hermatypic
stony corals. At the time, anthropogenic impacts were negligible apart from some fishing
activity in the marine area adjacent to the reef. However evidence of storm damage and
white band disease was observed in the shallow water Acropora palmata. Like Diadema
die off, high mortality of A. plamata due to white band disease was also reported in
Tobago (Laydoo 1985g), and by extension, a region wide phenomenon. Nonetheless, the
diverse marine life and relatively undisturbed environment at Culloden Bay led Laydoo
(1985h) to suggest that the reef system can represent a control site in monitoring
environmental impacts at other reef localities in Tobago.
Laydoo (1985d) provides the only literature to date on the nature and distribution of reefs
in Arnos Vale. It was found that reefs here had lower species diversity compared to other
reef localities around Tobago (Table 1.2). The smaller horizontal and vertical extent of
the reef areas in the bay was proposed as a reason for this. Nonetheless, it was a popular
area for snorkellers although it was found that the reefs remained generally undisturbed
by their activities. In addition to this, environmental factors that could be detrimental to
marine life, such as sedimentation and pollution, were minimal.
In an executive summary of the ecological survey of reefs around Tobago (Laydoo
1985h) several conclusions were arrived at. These included the fact that extensive
distribution of coral rubble, observed in many shallow reef areas, could be attributed to
the effects of storms and hurricanes. This rubble framework in turn contributed to an
enhanced habitat that led to high fish diversity and abundance on the reefs. Laydoo
(1985h) also concluded that conflicts existed in space utilization at many of the localities
investigated, especially between artisanal fishing activities and marine tourism and
recreation activities. Similar conflicts still remain today.
In 2004, while preparing the State of the Marine Environment Report, it became apparent
that there was a lack of recent information on the state of reefs in Tobago except for
6
Buccoo Reef which has been monitored under the CARICOMP project. In addition,
there have been many requests from the public for information on the state of reefs.
Thus, commencing in late 2007, through the IMA’s Coral Reef Monitoring Project,
which is a component of the larger Coastal Conservation Project, a re-surveying of the
major reefs in Tobago took place.
This research project was designed to address the lack of information on the health of the
major reef systems.
Reefs at Buccoo, Culloden, Arnos Vale, Man-o-War Bay and
Speyside, which were qualitatively and quantitatively surveyed in the 1980s, were resurveyed. The aim was to identify changes/impacts to these areas. In addition, the
fringing reefs of La Guira Bay were also surveyed. Little qualitative and more so,
quantitative coral reef research has been carried out here (IMA 1990) although it is well
known that diverse reefs, increasing in popularity as dive sites, can be found in this area.
7
2.0
METHODOLOGY
Surveys of reefs in six areas of Tobago (Figure 2.1) were conducted using a belt-quadrat
method (Dodge et al. 1982) to quantitatively describe the non-living and living benthos in
terms of species frequency, density and cover. In five of the reef areas, their associated
sampling sites were determined using maps from Laydoo (1985a-e). A sixth area with
reefs, La Guira Bay – located on the Atlantic side of southwest Tobago – was not
previously surveyed by Laydoo but the lack of quantitative data of reefs in this region
and its increasing importance in dive tourism warranted its inclusion in this study. Here
major dive spots in the area were selected as locations for sample sites. Survey depths at
each of the sampling localities throughout the reef areas in Tobago were 3m, 9m, 16m
and 21m, fore-reef slope structure permitting (Table 2.1).
Figure 2.1:
Map of Tobago
8
Table 2.1: Depths surveyed at the various sampling sites located in the different reef areas
studied around Tobago. Number of survey depths was dependent upon the
fore-reef slope structure at the sites
Area
Sampling Site
Surveying Depths
Arnos Vale Bay (Figure 2.2)
Eastern side of Arnos Vale Bay
3m, 9m
Western side of Arnos Vale Bay
9m
Eastern Reef, Buccoo
3m, 9m
Outer Reef, Buccoo
3m, 9m, 16m
Northern Reef, Buccoo
3m, 9m, 16m, 21m
Western Reef, Buccoo
3m, 9m, 16m, 21m
Eastern side of Culloden Bay
3m, 9m, 16m, 21m
Western side of Culloden Bay
9m, 16m
Eastern side of Booby Island
3m, 9m, 16m, 21m
Western side of Booby Island
3m, 9m
Rest House Reef
3m
Pirate's Reef
3m, 9m
Dive site known as Cove Ledge
(2 sites)
9m
Dive site known as Majeston (2 sites)
9m
Flying Reef (5 sites)
9m
In line with concrete Jetty adjacent to white
house on Goat Island
3m, 9m, 16m, 21m
Approximately 100m South of jetty
3m, 9m, 16m, 21m
Approximately 100m North of jetty
3m, 9m, 16m, 21m
Buccoo (Figure 2.3)
Culloden Bay (Figure 2.4)
Man-o-War Bay (Figure 2.5)
La Guira Bay (Figure 2.6)
Speyside (Figure 2.7)
A methodology similar to that adopted by Laydoo (1985a-e) was applied to allow for
easier comparison of the two studies. At each sampling depth a sequence of eight 1.0 m 2
quadrats were photographed. A sample area of 8.0m2 was previously determined to be
optimum by Laydoo (1985a-e) through the use of a species area curve. At the respective
depths at each sampling locality the starting point for photographs i.e. photoquadrat 1,
was selected at random with successive photoquadrats taken thereafter at 2m intervals
along the contours.
9
Figure 2.2: Map of Arnos Vale Reef showing general location of survey sites
10
Figure 2.3: Map of Buccoo Reef showing general location of survey sites
11
Figure 2.4: Map of Culloden Bay showing general location of survey sites
12
Figure 2.5: Map of Man-o-War Reef showing general location of survey sites
13
Figure 2.6: Map of La Guira Bay showing general location of survey sites
14
Figure 2.7: Map of Speyside Reef showing general location of survey sites
The photoquadrats were taken using a Canon S3-IS digital camera with an IKELITE W20 underwater wide angle conversion lens (magnification 0.56x). The camera was
enclosed in an IKELITE underwater housing. The entire setup was attached to a 1.3m rod
which maintained a fixed distance between camera and reef to ensure a minimum area of
1.0m2 was captured in each photoquadrat (Plate 2.1).
15
Plate 2.1: Photoquadrat from 16m depth at Western Reef, Buccoo
The photoquadrats were analysed using the National Coral Reef Institute (NCRI)/Nova
South-eastern University Oceanographic Centre’s Coral Point Count with Excel
extensions program (CPCe V 3.4). Through CPCe seventy five (75) random points were
applied to each photoquadrat. Laydoo in his 1985 studies used 450 points however use of
this many in these assessments was determined to be impractical. Seventy five random
points was found to be sufficient through the use of species recovery curves (Figure 2.8).
16
Figure 2.8:
Species recovery curves for eight photoquadrats at 9m Culloden West (Site A)
and 16m Buccoo Western Reef (Site B). Species recovery curves were used to
determine the appropriate number of random points to be used for analysis of
photoquadrats in this study
Sixteen photoquadrats, eight each from what were deemed, through preliminary
investigations, to be the two most species diverse sampling sites, were overlaid using
initially fifty (50) random points. The number of points was increased by increments of
five until all coral species within photoquadrat fell under at least one random point over
the series of overlays. The maximum number of points needed to do this during the
testing of the sixteen photoquadrats was then taken as the number to be used in
photoquadrat analysis in the study.
In the study, the non-living/living bottom underlying each random point was identified.
Living bottom was identified to species where possible, especially in the case of hard
corals, and the results expressed as mean species cover (% m-2) and frequency (%). The
number of colonies, irregardless of whether or not they underlay a random point, of each
hard coral species, gorgonian (family level primarily and genus level in the cases of
17
Pseudopterogorgia, Erythropodium and Briareum) and sponges (family level) in the
photoquadrat was also counted to obtain mean densities (col. m-2).
The AGRRA (2005) rapid assessment method was also applied to obtain information on
additional parameters such as recruitment, presence/absence of Diadema antillarum and
disease and bleaching occurrence. A twenty (20) metre transect line was laid just above
the reef surface at each sample depth. In disease/bleaching assessment, any stony coral
for which any part of its skeleton underlay the transect line was observed. Affected coral
species and percentage of coral surface impacted was recorded. The type of coral
disease/severity of discolouration (for bleaching) was also noted. Recruitment was
analysed by recording any hard coral species smaller than 2cm in diameter within a half
metre belt on either side of the transect line. Any Diadema antillarum seen within these
half metre zones were also recorded.
18
3.0
3.1
RESULTS
ARNOS VALE
Arnos Vale’s reefs extended to a maximum depth of about 10m allowing for surveys to
be conducted at only two depths. At an eastern locality, the reef flat at 3m and upper fore
reef at 9m was surveyed while only a depth of 9m was surveyed at a western locality
(Figure 2.2).
At 3m the total live bottom cover was very high (97.8%) with encrusting coralline algae
(41.2% cover) and the zoanthid Palythoa caribaeorum (39.3% cover) dominating the
species assemblage (Table 3.1.1). Hard coral made up only 11.2% of the benthos with
Millepora complanata (6% cover, 1.375 col.m-2) and, to a lesser extent, the knobby brain
coral Diploria clivosa (2.1% cover, 1.5 col.m-2) dominating among the 7 hard coral
species recorded (Table 3.1.2).
In comparison to the other major groups recorded,
sponges (4.8% cover) and gorgonians (1.3% cover) covered a very limited amount of the
benthos.
Table 3.1.1:
Species cover on reef crest (3m) at Arnos Vale survey site
Arnos Vale 3m
MAJOR CATEGORY (% of transect)
Species (% of transect)
Arnos Vale East
MEAN
11.17
11.17
Diploria clivosa
2.17
2.17
Diploria strigosa
0.83
0.83
Favia fragum
0.33
0.33
Meandrina meandrites
0.50
0.50
Millipora alcicornis
0.33
0.33
Millipora complanata
6.00
6.00
Porites astreoides
1.00
1.00
1.33
1.33
Erythropodium
0.33
0.33
Gorgonian (general)
1.00
1.00
4.83
4.83
HARD CORAL
GORGONIANS
SPONGES
ZOANTHIDS
39.33
39.33
Palythoa sp.
39.17
39.17
Zoanthid (general)
0.17
0.17
ENCRUSTING CORALLINE ALGAE
41.17
41.17
SAND, PAVEMENT, RUBBLE
2.17
2.17
19
Table 3.1.2:
Species mean density and frequency on reef crest (3m) at Arnos Vale survey
site
Arnos Vale 3m
-2
Mean Density (col. m ) (n=8)
Frequency (%)
Arnos Vale East
Arnos Vale East
1.5
62.5
Diploria strigosa
0.5
37.5
Favia fragum
0.75
25
0.125
12.5
0.125
12.5
1.375
62.5
Porites astreoides
0.375
37.5
Erythropodium
0.25
12.5
Gorgonian (general)
0.5
25
Sponge
3.5
87.5
Species
Diploria clivosa
At 9m the total mean live cover dropped to about 60%. Here a red macroalgae (unknown
species: tuft like, growing on rubble) dominated with an average cover of 22.2±0.2%
(Table 3.1.3). Mean hard coral cover was 14±7.5% although cover at the western survey
site was more than twice that at the eastern locality (19.3% and 8.7% cover respectively).
On average however, no one hard coral species dominated out of the 14 recorded.
Diploria strigosa (4.5±0.7%) and Montastrea cavernosa (3.7±4%) had the highest
coverages. Encrusting coralline algae also had a fair mean percentage cover
(12.9±17.3%) although this was largely because it made up 25.2% of the cover at the
western survey site with only 0.7% cover recorded at the eastern site. All the other major
category groupings – sponges, gorgonians and zoanthids each had approximately 5% or
less mean cover although sponge cover was relatively high (7.8%, 4.25col.m-2) at the
western locality (Table 3.1.4).
20
Table 3.1.3: Species cover on the upper fore reef (9m) at Arnos Vale survey sites
Arnos Vale 9m
Arnos Vale East
Arnos Vale West
MEAN
STD. DEV.
STD. ERROR
8.67
19.33
14.00
7.54
5.33
Agaricia agaricites
0.00
0.33
0.17
0.24
0.17
Dichocoenia stokesi
0.00
0.50
0.25
0.35
0.25
Diploria labyrinthiformis
0.17
1.17
0.67
0.71
0.50
Diploria strigosa
5.00
4.00
4.50
0.71
0.50
0.17
0.83
0.50
0.47
0.33
1.17
0.83
1.00
0.24
0.17
0.00
1.50
0.75
1.06
0.75
Montastraea cavernosa
0.83
6.50
3.67
4.01
2.83
Montastrea faveolata
0.00
2.50
1.25
1.77
1.25
Mycetophyllia ferox
0.17
0.00
0.08
0.12
0.08
Porites astreoides
0.17
0.50
0.33
0.24
0.17
Scolymia cubensis
0.00
0.17
0.08
0.12
0.08
Siderastrea radians
0.50
0.17
0.33
0.24
0.17
Siderastrea siderea
0.50
0.33
0.42
0.12
0.08
6.00
2.00
4.00
2.83
2.00
Briareum
0.83
0.00
0.42
0.59
0.42
Erythropodium
1.33
0.33
0.83
0.71
0.50
Gorgonian (general)
0.83
0.50
0.67
0.24
0.17
Pseudopterogorgia
HARD CORAL
GORGONIANS
3.00
1.17
2.08
1.30
0.92
SPONGES
3.00
7.83
5.42
3.42
2.42
ZOANTHIDS
0.83
2.67
1.75
1.30
0.92
0.83
2.67
1.75
1.30
0.92
22.00
22.33
22.17
0.24
0.17
Palythoa sp.
MACROALGAE
22.00
22.33
22.17
0.24
0.17
Macroalgae (general)
0.67
25.17
12.92
17.32
12.25
58.83
20.67
39.75
26.99
19.08
21
Table 3.1.4: Species mean density and frequency on the upper fore reef (9m) at Arnos Vale survey
sites
Arnos Vale 9m
Species
-2
Frequency (%)
Arnos Vale East
Arnos Vale West
Arnos Vale East
Arnos Vale West
Agaricia agaricites
0
0.625
0
12.5
Dichocoenia stokesi
0
0.25
0
12.5
0.125
0.25
12.5
25
Diploria strigosa
1.375
2.875
87.5
62.5
0.125
0.5
12.5
25
1.25
1
62.5
37.5
0.125
0.375
0
25
0.375
2.5
25
75
0
0.5
0
25
Mycetophyllia ferox
0.125
0
12.5
0
Porites astreoides
0.125
0.25
12.5
25
Scolymia cubensis
0
0.125
0
12.5
Siderastrea radians
0.625
0.5
37.5
12.5
Siderastrea siderea
0.125
0.125
12.5
12.5
Briareum
0.625
0
37.5
0
Erythropodium
0.75
0.25
50
25
Gorgonian (general)
1.25
0.75
50
12.5
Pseudopterogorgia
1.5
0.625
37.5
37.5
3
4.25
87.5
100
0.125
0
n/a
n/a
Sponge
Diploria clivosa
22
3.2
BUCCOO
The fore reef slope structure on the Buccoo Reef allowed for surveys to be conducted at all four
depths at two sites (Northern reef and Western reef), 3m through 16m depths at Outer reef and
only the two shallowest depths at Eastern reef (Figure 2.3).
The total mean live cover at 3m was just under 80% with Palythoa caribaeorum, a zooanthid,
making up on average, 32±40.9% out of that live cover (Table 3.2.1). There was great variability
in Palythoa cover throughout the survey localities however, with 86.3% and 40.7% cover at
Outer and Northern reefs respectively, whereas there was less than 1% cover at Western reef. At
Eastern reef no Palythoa was recorded.
Encrusting coralline alga was also a dominant component of the benthos at 3m (22.8±19.5%
mean cover) but like Palythoa was also highly variable among survey sites. Mean macroalgal
cover was 14.3±16.9% at this depth. However, macroalgae and Palythoa coverage varied
inversely - macroalgal cover was high (35% at Western reef and 21.3% at Eastern reef) where
Palythoa coverage was low and vice versa. There was very little to no macroalgal cover at the
Outer and Northern reef sites. Mean hard coral cover was only 5.6±4.3% with Millipora sp.
making up over half of this figure. Millipora complanata coverage (9.3%) (Table 3.2.1) and
density (6.25 col.m-2) (Table 3.2.2) was particularly high at Eastern reef. Gorgonians (2.6±4.7%)
and sponges (1.4±1.3%) showed very low coverage at 3m.
Encrusting coralline algae dominated the living benthos at 9m accounting for 38.8±38.7% of the
total mean living cover, which was about 71% (Table 3.2.3). Variability in cover among sites
was high, ranging from 0% at Eastern reef to 82.3% at Northern reef. At this depth, mean hard
coral and gorgonian cover were both about 14% each with Montastrea faveolata dominating
(6.3±5.1%) the cover for the 12 hard coral species recorded, and Erythropodium caribaeorum
(5.8±2.9%) doing the same for the gorgonian category. Interestingly, hard coral cover decreased
steadily from site to site as one moved in an east to west direction around the arc of reef
platforms that make up part of the Buccoo Reef complex. It was also observed that on average,
23.2±17.3% of the coral was affected by yellow band disease. The highest incidences took place
23
Table 3.2.1: Species cover on the reef crest (3m) at Buccoo survey sites
Buccoo 3m
Buccoo Eastern Reef
Buccoo Outer Reef
Buccoo Northern Reef
Buccoo Western Reef
MEAN
STD. DEV.
STD. ERROR
11.50
2.33
2.50
6.17
5.63
4.30
2.15
Acropora palmata
0.00
0.00
0.00
2.33
0.58
1.17
0.58
Diploria clivosa
0.00
0.00
0.67
3.67
1.08
1.75
0.88
Diploria strigosa
0.00
0.00
0.17
0.00
0.04
0.08
0.04
Favia fragum
0.00
0.00
0.17
0.17
0.08
0.10
0.05
1.33
1.83
0.67
0.00
0.96
0.80
0.40
9.33
0.50
0.50
0.00
2.58
4.51
2.25
Montastraea annularis
0.33
0.00
0.00
0.00
0.08
0.17
0.08
Porites astreoides
0.50
0.00
0.33
0.00
0.21
0.25
0.13
0.83
0.00
9.67
0.00
2.63
4.71
2.36
Erythropodium
0.83
0.00
0.67
0.00
0.38
0.44
0.22
Gorgonian (general)
0.00
0.00
9.00
0.00
2.25
4.50
2.25
1.50
0.33
3.17
0.67
1.42
1.27
0.63
0.00
86.33
40.67
0.83
31.96
40.92
20.46
0.00
86.33
40.67
0.83
31.96
40.92
20.46
21.33
0.67
0.33
35.00
14.33
16.92
8.46
Halimeda
0.00
0.00
0.33
0.17
0.13
0.16
0.08
21.33
0.67
0.00
34.83
14.21
16.95
8.47
2.17
10.00
40.17
38.67
22.75
19.52
9.76
62.67
0.33
3.50
18.67
21.29
28.72
14.36
HARD CORAL
GORGONIANS
SPONGES
ZOANTHIDS
Palythoa sp.
MACROALGAE
24
Table 3.2.2: Species mean density and frequency on the reef crest (3m) at Buccoo survey sites
-2
Buccoo 3m
Species
Frequency (%)
Buccoo Eastern
Buccoo Outer
Buccoo Northern
Buccoo Western
Buccoo Eastern
Buccoo Outer
Buccoo Northern
Buccoo Western
Reef
Reef
Reef
Reef
Reef
Reef
Reef
Reef
0
0
0
0.125
0
0
0
12.5
Diploria clivosa
0
0
0.375
2
0
0
37.5
100
Diploria strigosa
0.125
0
0.125
0
0
0
12.5
0
0
0
0.25
0.125
0
0
12.5
12.5
1.625
1.375
0.75
0
50
75
37.5
0
6.25
0.375
0.25
0
75
12.5
25
0
0.25
0
0
0
12.5
0
0
0
Porites astreoides
0.25
0
0.125
0
12.5
0
12.5
0
Erythropodium
0.5
0
0.5
0
37.5
0
25
0
Acropora palmata
Favia fragum
Gorgonian (general)
Sponge
0
0
4
0
0
0
75
0
0.875
0.125
1.125
0.625
50
12.5
37.5
37.5
25
Table 3.2.3: Species cover on the upper fore reef (9m) at Buccoo survey sites
Buccoo 9m
Buccoo Eastern Reef
Buccoo Outer Reef
Buccoo Western Reef
MEAN
STD. DEV.
STD. ERROR
20.50
17.67
10.00
7.00
13.79
6.34
3.17
Agaricia agaricites
0.00
0.00
0.50
0.00
0.13
0.25
0.13
Colpophyllia natans
0.00
1.33
0.00
0.83
0.54
0.66
0.33
0.00
0.00
0.33
0.50
0.21
0.25
0.13
Diploria strigosa
0.00
0.00
1.17
1.67
0.71
0.84
0.42
Eusmilia fastigiata
0.00
0.00
0.00
0.33
0.08
0.17
0.08
11.50
0.33
1.33
0.00
3.29
5.50
2.75
5.33
0.50
0.17
0.00
1.50
2.56
1.28
1.00
0.00
0.00
0.00
0.25
0.50
0.25
2.33
13.50
6.17
3.00
6.25
5.11
2.56
Porites astreoides
0.33
0.17
0.33
0.00
0.21
0.16
0.08
Porites porites
0.00
0.00
0.00
0.67
0.17
0.33
0.17
Siderastrea siderea
0.00
1.83
0.00
0.00
0.46
0.92
0.46
HARD CORAL
GORGONIANS
4.17
12.33
5.67
32.83
13.75
13.21
6.60
Briareum
0.00
0.00
0.00
18.00
4.50
9.00
4.50
Erythropodium
4.17
7.50
2.50
8.83
5.75
2.92
1.46
Gorgonian (general)
0.00
2.17
3.17
4.67
2.50
1.96
0.98
Pseudopterogorgia
0.00
2.67
0.00
1.33
1.00
1.28
0.64
4.50
0.33
0.00
0.00
1.21
2.20
1.10
0.00
0.50
1.67
0.00
0.54
0.79
0.39
0.00
0.50
1.67
0.00
0.54
0.79
0.39
6.67
0.00
0.00
3.17
2.46
3.18
1.59
Halimeda
0.00
0.00
0.00
2.67
0.67
1.33
0.67
6.67
0.00
0.00
0.50
1.79
3.26
1.63
0.00
59.67
82.33
13.17
38.79
38.70
19.35
64.17
9.50
0.33
43.83
29.46
29.77
14.88
SPONGES
ZOANTHIDS
Palythoa sp.
MACROALGAE
26
at the Outer and Northern reefs sampling locations with 38.7% and 36.7% of corals
affected respectively. Yellow band disease primarily affected Monatstrea faveolata.
Mean macroalgal (2.5±3.2%) and sponge (1.2±2.2%) cover at this depth were very low.
However, at Eastern reef in particular, macroalgal cover (6.67%) and sponge cover
(4.5%, 3.375 col.m-2) (Table 3.2.4) was especially above the average.
At 16m depth mean hard coral cover was highest (30.4±1.4%) (Table 3.2.5) when
compared with all other survey depths on the Buccoo reef. Hard coral cover was
consistently high at all survey sites with Montastrea faveolata dominating at Outer reef
(16.2%, 2.5 col.m-2) and Northern reef (9.7%, 3.125 col.m-2) and Colpophyllia natans at
Western reef (11.3%, 1 col.m-2) (Table 3.2.6). Fourteen hard coral species were recorded
and this was the highest number recorded at any depth in Buccoo. Encrusting coralline
algae also had substantial, consistent coverage throughout with an average cover of
27.3±7%. Gorgonians were the only other major component of the living biota
(14.5±8.5% mean cover) with Erythropodium caribaeorum making up the vast majority
(8.9±2.7%) of this grouping. Gorgonian cover was more variable than that of hard corals
and coralline algae though, with 7.2%, 12.5% and 23.8% cover at Outer reef, Northern
reef and Western reef respectively. As alluded to earlier, out of the total mean living
cover of 74.2%, zoanthids (1.4±1.3%), sponge (0.4±0.5%) and macroalgal (0.2±0.3%)
cover were all extremely low.
Total mean live cover at 21m on the Buccoo reef was just under 80% with mean
encrusting coralline algal cover accounting for about half of this (40.4±3.7%) (Table
3.2.7). Although not as high as at 16m, mean hard coral cover was still good (21.5±7.3%)
with Western reef (26.7%) having 10% higher coverage than Northern reef (16.3%).
Montastrea faveolata (14.3%, 2.25 col.m-2 and 7.2%, 2 col.m-2 respectively) (Table 3.2.8)
once again dominated out of the 12 species identified at this depth. Although variable
(23.2% at Northern reef and 9% at Western reef) mean gorgonian cover was 16.1±10%
with Erythropodium caribaeorum largely dominating at both survey sites. Once again,
sponges (1.2±0.5% cover), macroalgae (0.3±0.5% cover) and zoanthids (0.2±0.2% cover)
were minorities in the benthic cover makeup.
27
Table 3.2.4: Species mean density and frequency on the upper fore reef (9m) at Buccoo survey sites
-2
Buccoo 9m
Species
Frequency (%)
Buccoo Eastern
Buccoo Outer
Buccoo Northern
Buccoo Western
Buccoo Eastern
Buccoo Outer
Buccoo Northern
Buccoo Western
Reef
Reef
Reef
Reef
Reef
Reef
Reef
Reef
Agaricia agaricites
0
0.125
0.375
0
0
0
25
0
Colpophyllia natans
0
0.5
0
0.5
0
37.5
0
25
0
0
0.125
0.125
0
0
12.5
12.5
Diploria strigosa
0
0
0.625
0.875
0
0
25
37.5
Eusmilia fastigiata
0
0
0
0.25
0
0
0
25
5.375
0.375
1
0
100
12.5
25
0
2.75
0.375
0.125
0
62.5
12.5
12.5
0
0.625
0
0
0
12.5
0
0
0
1.375
2.625
1.375
1.125
37.5
50
50
75
Porites astreoides
0.25
0.125
0.375
0
12.5
12.5
25
0
Porites porites
0
0
0
0.125
0
0
0
12.5
Siderastrea siderea
0
0.5
0
0
0
12.5
0
0
Briareum
0
0
0
3.25
0
0
0
62.5
Erythropodium
0.875
2.75
2.875
1.625
37.5
62.5
75
37.5
Gorgonian (general)
0
0.75
1.125
4.125
0
37.5
37.5
87.5
Pseudopterogorgia
0
0.5
0.125
0.375
0
37.5
0
25
3.375
0.375
0
0.125
100
25
0
0
0
0
0
0.125
n/a
n/a
n/a
n/a
Sponge
Scolymia cubensis
28
Table 3.2.5: Species cover on the mid fore reef (16m) at Buccoo survey sites
Buccoo 16m
Buccoo Outer Reef
Buccoo Western Reef
MEAN
STD. DEV.
STD. ERROR
31.00
31.33
28.83
30.39
1.36
0.78
Agaricia agaricites
0.00
0.50
0.50
0.33
0.29
0.17
Colpophyllia natans
2.00
8.83
11.33
7.39
4.83
2.79
0.33
0.67
0.33
0.44
0.19
0.11
Diploria strigosa
1.00
2.50
5.00
2.83
2.02
1.17
Madracis decactis
0.33
0.17
0.33
0.28
0.10
0.06
0.17
0.83
0.17
0.39
0.38
0.22
1.00
1.50
0.83
1.11
0.35
0.20
1.67
1.17
0.33
1.06
0.67
0.39
0.00
2.50
1.33
1.28
1.25
0.72
16.17
9.67
6.67
10.83
4.86
2.80
Porites astreoides
2.83
0.33
0.50
1.22
1.40
0.81
Porites porites
0.00
0.00
0.33
0.11
0.19
0.11
Siderastrea radians
0.33
0.33
0.00
0.22
0.19
0.11
Siderastrea siderea
5.17
2.33
1.17
2.89
2.06
1.19
7.17
12.50
23.83
14.50
8.51
4.91
Briareum
0.00
2.00
0.00
0.67
1.15
0.67
Erythropodium
6.83
7.83
12.00
8.89
2.74
1.58
Gorgonian (general)
0.00
1.83
0.83
0.89
0.92
0.53
Pseudopterogorgia
HARD CORAL
GORGONIANS
0.33
0.83
11.00
4.06
6.02
3.48
SPONGES
0.00
0.17
1.00
0.39
0.54
0.31
ZOANTHIDS
0.00
2.67
1.50
1.39
1.34
0.77
0.00
2.67
1.50
1.39
1.34
0.77
0.00
0.00
0.50
0.17
0.29
0.17
Palythoa sp.
MACROALGAE
0.00
0.00
0.50
0.17
0.29
0.17
Halimeda
25.00
35.17
21.83
27.33
6.97
4.02
36.83
18.17
22.50
25.83
9.77
5.64
29
Table 3.2.6: Species mean density and frequency on the mid fore reef (16m) at Buccoo survey sites
-2
Buccoo 16m
Species
Frequency (%)
Buccoo Outer
Reef
Buccoo Western Reef
Buccoo Outer Reef
Buccoo Western Reef
Agaricia agaricites
0.125
1.125
0.625
0
25
37.5
Colpophyllia natans
0.125
0.625
1
12.5
50
62.5
0.125
0.25
0.125
12.5
25
12.5
Diploria strigosa
0.25
0.75
0.75
25
50
50
Madracis decactis
0.125
0.125
0.25
12.5
12.5
25
0.125
0.125
0.5
12.5
12.5
12.5
0.875
1.5
0.625
25
50
25
0.5
0.25
0.25
25
25
12.5
0
0.5
0.625
0
25
62.5
2.5
3.125
2.25
75
100
87.5
Porites astreoides
1.5
0.125
1.125
75
12.5
25
Porites porites
0
0
0.125
0
0
12.5
Siderastrea radians
0.375
0.125
0
25
12.5
0
Siderastrea siderea
1.125
1.375
0.5
62.5
62.5
50
0
0.5
0
0
25
0
Briareum
Erythropodium
1.25
2.25
3.125
87.5
100
100
Gorgonian (general)
0
1
0.75
0
62.5
37.5
Pseudopterogorgia
0.25
0.25
2.5
12.5
12.5
87.5
Sponge
0.125
0.25
0.5
0
12.5
37.5
Scolymia cubensis
0.125
0
0.125
n/a
n/a
n/a
30
Table 3.2.7: Species cover on the lower fore reef (21m) at Buccoo survey sites
Buccoo 21m
Species (% of transect
Buccoo Western Reef
MEAN
STD. DEV.
STD. ERROR
16.33
26.67
21.50
7.31
5.17
Agaricia agaricites
0.33
0.50
0.42
0.12
0.08
Colpophyllia natans
4.83
0.00
2.42
3.42
2.42
0.17
0.17
0.17
0.00
0.00
Diploria strigosa
0.00
6.00
3.00
4.24
3.00
Eusmilia fastigiata
0.17
0.67
0.42
0.35
0.25
Madracis decactis
0.17
1.00
0.58
0.59
0.42
1.17
0.00
0.58
0.82
0.58
0.50
0.33
0.42
0.12
0.08
0.17
1.33
0.75
0.82
0.58
7.17
14.33
10.75
5.07
3.58
Porites astreoides
0.17
1.50
0.83
0.94
0.67
Siderastrea siderea
1.50
0.83
1.17
0.47
0.33
HARD CORAL
GORGONIANS
23.17
9.00
16.08
10.02
7.08
Erythropodium
20.33
7.33
13.83
9.19
6.50
Gorgonian (general)
1.33
0.67
1.00
0.47
0.33
Pseudopterogorgia
1.50
1.00
1.25
0.35
0.25
SPONGES
0.83
1.50
1.17
0.47
0.33
ZOANTHIDS
0.33
0.00
0.17
0.24
0.17
0.33
0.00
0.17
0.24
0.17
0.67
0.00
0.33
0.47
0.33
Palythoa sp.
MACROALGAE
0.67
0.00
0.33
0.47
0.33
DEAD CORAL WITH ALGAE
0.33
0.00
0.17
0.24
0.17
37.83
43.00
40.42
3.65
2.58
20.50
19.83
20.17
0.47
0.33
31
Table 3.2.8: Species mean density and frequency on the lower fore reef (21m) at Buccoo survey sites
Buccoo 21m
Species
-2
Frequency (%)
Buccoo Western Reef
Buccoo Western Reef
Agaricia agaricites
0.875
0.5
25
12.5
Colpophyllia natans
0.5
0
37.5
0
0.125
0.125
12.5
12.5
0
0.5
0
37.5
Eusmilia fastigiata
0.125
0.125
12.5
12.5
Madracis decactis
0.125
0.375
12.5
25
0.875
0
37.5
0
0.25
0.125
25
12.5
0.125
0.625
12.5
50
2.25
2
100
100
Porites astreoides
0.125
0.75
12.5
50
Siderastrea siderea
0.375
0.375
37.5
25
Erythropodium
3.875
2.5
100
87.5
Gorgonian (general)
0.75
0.5
37.5
25
Pseudopterogorgia
0.375
0.75
37.5
62.5
Sponge
0.125
0.75
12.5
37.5
Briareum
0
0.25
n/a
n/a
Scolymia cubensis
0
0.125
n/a
n/a
Mycetophyllia sp.
0
0.125
n/a
n/a
Diploria strigosa
32
3.3
CULLODEN
Reefs at eastern locality of Culloden were quite extensive and allowed for surveys to take
place at all four sampling depths (Figure 2.4). At the western site, however, due to fore
reef slope structure, surveys were conducted at only two depths; 9m and 16m.
Of the approximate 98% live cover observed at 3m in the Culloden area, encrusting
coralline algae made up about 50% and Palythoa caribaeorum made up about 32%
coverage (Table 3.3.1). In comparison, sponge cover at this depth was 6.3% however this
was the highest mean sponge cover for all depths surveyed in Culloden. Similarly, the
sponge density of 4.25 col.m-2 was also the highest observed when compared to all the
other localities surveyed (Table 3.3.4). Nonetheless, in this reef crest zone, like sponge
cover, coverage of hard corals (4.5%) and gorgonians (4.8%) was relatively low. They
were all higher than macroalgal cover (1.3%) though, which for the most part was
identified as Halimeda sp.
Total mean live cover at 9m was lower (71.2%) than at 3m but dominance was more
evenly distributed among the major categories. Encrusting coralline alga was once again
most dominant with just under 31±12.2% mean cover (Table 3.3.3). The 16 species of
hard corals recorded had an average cover of 16.3±4.7% with Montastrea faveolata
accounting for about a third of this (5.7±7.5%). This species was especially abundant at
the western locality – 11% (0.75 col.m-2 density) out of 20% hard coral cover compared
to 0.3% (0.25 col.m-2 density) out of 13% hard coral cover at the eastern site (Table
3.3.4). Consequently, so was the noted occurrence of yellow band disease which has an
affinity to this species in particular. It affected nearly 13% of the hard corals captured in
the photoquadrats taken at this western site while none were affected in the Eastern site’s
photoquadrats.
Gorgonians at 9m had a mean cover of about 13±10.8% but coverage at the eastern
survey site was much higher (20.8%) compared to that of the western site (5.5%) (Table
3.3.3). This was also the case with sponge cover where, although the mean cover was low
(3.8±4.5%), 7% coverage was recorded at the eastern locality compared with 0.7% at the
33
western site. About five percent (4.9±2.5%) mean zoanthid cover and just under 2%
mean macroalgal cover made up the remainder of the total mean live cover.
Table 3.3.1: Species cover on the reef crest (3m) at Culloden survey site
Culloden 3m
Culloden East
MEAN
4.50
4.50
Diploria clivosa
0.67
0.67
0.33
0.33
Diploria strigosa
1.33
1.33
Favia fragum
0.17
0.17
0.50
0.50
0.17
0.17
0.50
0.50
0.17
0.17
0.33
0.33
Porites astreoides
0.33
0.33
4.83
4.83
Briareum
0.17
0.17
Erythropodium
0.17
0.17
Gorgonian (general)
3.83
3.83
Pseudopterogorgia
0.67
0.67
6.33
6.33
31.67
31.67
31.67
31.67
1.33
1.33
HARD CORAL
GORGONIANS
SPONGES
ZOANTHIDS
Palythoa sp.
MACROALGAE
Halimeda
1.33
1.33
49.50
49.50
1.83
1.83
34
Table 3.3.2: Species mean density and frequency on the reef crest (3m) at Culloden survey
site
Culloden 3m
-2
Frequency (%)
Culloden East
Culloden East
Diploria clivosa
0.25
25
0.125
12.5
Diploria strigosa
0.25
12.5
Favia fragum
0.125
12.5
0.125
12.5
0.125
12.5
0.625
37.5
0.125
12.5
0.125
12.5
Porites astreoides
0.625
25
Briareum
0.125
12.5
Erythropodium
0.125
12.5
Gorgonian (general)
2.125
100
Pseudopterogorgia
0.125
12.5
Sponge
4.25
75
Species
35
Table 3.3.3: Species cover on the upper fore reef (9m) at Culloden survey sites
Culloden 9m
Culloden East
Culloden West
MEAN
STD. DEV.
STD. ERROR
13.00
19.67
16.33
4.71
3.33
Agaricia agaricites
2.00
0.00
1.00
1.41
1.00
Colpophyllia natans
1.33
0.67
1.00
0.47
0.33
0.50
0.17
0.33
0.24
0.17
Diploria strigosa
0.83
2.50
1.67
1.18
0.83
Eusmilia fastigiata
0.50
0.00
0.25
0.35
0.25
Isophyllia rigida
0.00
0.17
0.08
0.12
0.08
Madracis decactis
0.83
0.33
0.58
0.35
0.25
0.50
2.33
1.42
1.30
0.92
1.67
0.17
0.92
1.06
0.75
1.17
0.67
0.92
0.35
0.25
2.00
0.83
1.42
0.82
0.58
0.33
11.00
5.67
7.54
5.33
Porites astreoides
0.00
0.17
0.08
0.12
0.08
Scolymia cubensis
0.17
0.00
0.08
0.12
0.08
Siderastrea radians
0.33
0.33
0.33
0.00
0.00
Siderastrea siderea
0.83
0.33
0.58
0.35
0.25
20.83
5.50
13.17
10.84
7.67
2.33
3.67
3.00
0.94
0.67
Gorgonian (general)
7.67
0.00
3.83
5.42
3.83
Pseudopterogorgia
10.83
1.83
6.33
6.36
4.50
SPONGES
7.00
0.67
3.83
4.48
3.17
ZOANTHIDS
3.17
6.67
4.92
2.47
1.75
Palythoa sp.
3.00
6.67
4.83
2.59
1.83
Zoanthid (general)
0.17
0.00
0.08
0.12
0.08
1.83
1.83
1.83
0.00
0.00
Halimeda
1.83
1.50
1.67
0.24
0.17
0.00
0.33
0.17
0.24
0.17
0.83
0.00
0.42
0.59
0.42
22.00
39.33
30.67
12.26
8.67
31.33
26.33
28.83
3.54
2.50
HARD CORAL
GORGONIANS
Erythropodium
MACROALGAE
36
Table 3.3.4:
Species mean density and frequency on the upper fore reef (9m) at Culloden
survey sites
Culloden 9m
Species
-2
Frequency (%)
Culloden East
Culloden West
Culloden East
Culloden West
Agaricia agaricites
1.125
0.125
75
12.5
Colpophyllia natans
0.125
0.125
12.5
12.5
0.125
0.125
12.5
12.5
Diploria strigosa
0.375
2
25
50
Eusmilia fastigiata
0.125
0
12.5
0
Isophyllia rigida
0
0.125
0
12.5
Madracis decactis
0.875
0.125
37.5
12.5
0.25
0.25
12.5
12.5
0.75
0.375
37.5
12.5
0.5
0.125
12.5
12.5
1.125
0.5
62.5
37.5
0.25
0.75
25
50
Porites astreoides
0
0.25
0
12.5
Scolymia cubensis
0.25
0
12.5
0
Siderastrea radians
0.125
0.125
12.5
12.5
Siderastrea siderea
0.25
0.125
25
12.5
Erythropodium
1.25
2.375
50
75
3
0.125
100
0
Gorgonian (general)
Pseudopterogorgia
Sponge
Favia fragum
2.5
0.125
75
12.5
2.625
1
87.5
37.5
0
0.125
n/a
n/a
37
Total mean live cover at 16m was just over 88%. Here, mean encrusting coralline algae cover
continued to dominate the benthos. Its mean cover was more than three times higher than that
of the next highest major category, hard corals (55±18.2% compared to 17.9±8.1%) (Table
3.3.5). Like at 9m though, out of the 15 species of hard corals documented Montastrea
faveolata was once again most abundant with an average cover and density of 9.9±6% and
1.75 col.m-2 respectively (Table 3.3.6). Gorgonians had a mean cover of just under
11.8±5.4% with Pseudeopterogorgia sp. (5.6±4.1% cover) making up about half that
number.
Interestingly, the survey locality on the eastern side of Culloden had almost twice the hard
coral and gorgonian cover than the western side. However, Yellow Band disease occurrence
was also much higher here with 30.3% of the hard corals affected compared to 6.9% at the
western site. The remaining categories – sponges (1.3±0.2%), macroalgae (1.2±0.7%) and
zoanthids (0.9±1.3%) – had very low mean coverage at this depth.
High coverage of encrusting coralline algae was again observed at 21m making up just over
61% of the benthic cover (Table 3.3.7). Hard corals had similar coverage to that observed at
9m and 16m about 16%. At this depth however, Montastrea faveolata (4.5% cover) shared
its hard coral dominance with Meandrina meandrites (3.8% cover). The former was clearly
encountered more frequently however (Table 3.3.8). Gorgonians had about 10% cover with
Erythropodium caribaeorum (5.3%) accounting for just over half of this. Sponges made up
4% out of the approximate 92% live cover documented with almost negligible contribution
made from macroalgae (0.5%) and none from zoanthids.
38
Table 3.3.5: Species cover on the mid fore reef (16m) at Culloden survey sites
Culloden 16m
HARD CORAL
Culloden East
Culloden West
MEAN
STD. DEV.
STD. ERROR
23.67
12.17
17.92
8.13
5.75
Agaricia agaricites
0.33
0.17
0.25
0.12
0.08
Dichocoenia stokesi
0.00
0.33
0.17
0.24
0.17
0.17
0.00
0.08
0.12
0.08
Diploria strigosa
0.67
0.00
0.33
0.47
0.33
Madracis decactis
1.17
2.83
2.00
1.18
0.83
0.83
0.33
0.58
0.35
0.25
0.33
0.00
0.17
0.24
0.17
0.50
0.00
0.25
0.35
0.25
1.17
0.83
1.00
0.24
0.17
14.17
5.67
9.92
6.01
4.25
Mycetophyllia aliciae
0.00
0.17
0.08
0.12
0.08
Porites astreoides
0.00
0.33
0.17
0.24
0.17
Scolymia cubensis
0.00
0.17
0.08
0.12
0.08
Siderastrea radians
0.00
0.50
0.25
0.35
0.25
Siderastrea siderea
4.33
0.83
2.58
2.47
1.75
GORGONIANS
15.67
8.00
11.83
5.42
3.83
Briareum
0.00
0.33
0.17
0.24
0.17
Erythropodium
2.83
3.83
3.33
0.71
0.50
Gorgonian (general)
4.33
1.17
2.75
2.24
1.58
Pseudopterogorgia
8.50
2.67
5.58
4.12
2.92
SPONGES
1.50
1.17
1.33
0.24
0.17
ZOANTHIDS
1.83
0.00
0.92
1.30
0.92
1.83
0.00
0.92
1.30
0.92
1.67
0.67
1.17
0.71
0.50
Halimeda
1.67
0.50
1.08
0.82
0.58
0.08
Palythoa sp.
MACROALGAE
0.00
0.17
0.08
0.12
0.17
0.00
0.08
0.12
0.08
42.17
67.83
55.00
18.15
12.83
13.33
10.17
11.75
2.24
1.58
39
Table 3.3.6: Species mean density and frequency on the mid fore reef (16m) at Culloden survey
sites
Culloden 16m
Species
Agaricia agaricites
Dichocoenia stokesi
-2
Frequency (%)
Culloden East
Culloden West
Culloden East
Culloden West
0.125
0.125
12.5
12.5
0
0.125
0
12.5
0.125
0
12.5
0
Diploria strigosa
0.25
0.125
25
0
Madracis decactis
1.125
0.875
37.5
75
0.125
0.125
12.5
12.5
0.25
0
25
0
0.375
0
25
0
0.375
0.5
37.5
50
2.125
1.375
100
50
0
0.125
0
12.5
Porites astreoides
0
0.25
0
12.5
Scolymia cubensis
0
0.25
0
12.5
Siderastrea radians
0
0.375
0
25
Siderastrea siderea
1.375
0.5
75
37.5
0
0.25
0
12.5
1.5
2.375
62.5
75
Gorgonian (general)
1.875
0.375
100
12.5
Pseudopterogorgia
2.375
0.75
75
37.5
1
1.125
62.5
50
Briareum
Erythropodium
Sponge
40
Table 3.3.7: Species cover on the lower fore reef (21m) at Culloden survey site.
Culloden 21m
Culloden East
MEAN
15.67
15.67
Agaricia agaricites
0.33
0.33
Dichocoenia stokesi
0.50
0.50
Diploria strigosa
0.67
0.67
Leptoseris cucullata
0.17
0.17
Madracis decactis
1.67
1.67
3.83
3.83
1.33
1.33
4.50
4.50
Porites astreoides
0.50
0.50
Scolymia cubensis
0.17
0.17
Siderastrea radians
0.17
0.17
Siderastrea siderea
1.83
1.83
10.17
10.17
Briareum
2.00
2.00
Erythropodium
5.33
5.33
Gorgonian (general)
2.67
2.67
Pseudopterogorgia
0.17
0.17
SPONGES
4.00
4.00
MACROALGAE
0.50
0.50
HARD CORAL
GORGONIANS
0.50
0.50
61.33
61.33
8.33
8.33
41
Table 3.3.8: Species mean density and frequency on the lower fore reef (21m) at Culloden
survey site
Culloden 21m
Species
-2
Frequency (%)
Culloden East
Culloden East
Agaricia agaricites
0.375
25
Dichocoenia stokesi
0.125
12.5
Diploria strigosa
0.25
12.5
0.125
12.5
Madracis decactis
1.125
75
0.375
37.5
0.75
37.5
1.5
87.5
Porites astreoides
0.25
12.5
Scolymia cubensis
0.25
12.5
Siderastrea radians
0.125
12.5
Siderastrea siderea
0.375
37.5
Briareum
0.75
50
Erythropodium
2.25
75
Gorgonian (general)
1.75
50
Pseudopterogorgia
0.125
12.5
Sponge
0.75
25
42
3.4
MAN-O-WAR BAY
The reefs in Man-o-War Bay were not deep with the exception of Booby Island, where the
eastern side was surveyed at 21m. Reefs at the three remaining sites extended to depths of just
over 10m except for Rest House Reef whose reefs had a maximum depth of about 7m (Figure
2.5).
At 3m zoanthids were the dominant group accounting for, on average, 23.6±24.7% of the total
mean live cover of about 61% (Table 3.4.1). Palythoa caribaeorum cover was very high at the
Booby Island west (54.3%) and Pirate’s reef (32.8%) sites leading to this high mean zoanthid
cover. At the two remaining sites very little to no zoanthids were recorded. Mean hard coral
cover was 20.3±15.1% and this figure is the highest recorded at any 3m reef area surveyed
during this study. This mean cover figure is deceptive though, as the variability among the four
reef crest sites surveyed in Man-O-War bay was high. While the hard coral cover at the Booby
Island east and west sites and Pirate’s reef site were above the Tobago wide norm (about 12%,
14% and 13% cover respectively), it was the 42.8% cover at the Rest House reef locality that
really increased the hard coral cover average.
The Rest House reef site at 3m was dominated almost entirely by the yellow pencil coral
Madracis mirabilis (42.3% cover, 2.375 col.m-2 density) (Table 3.4.2) and with the fragile nature
of this species the high percentage cover of coral rubble with algae here (41.7%) was expected.
Millipora sp. was common at the Pirate’s reef site but especially so at the western side of Booby
Island where all hard coral recorded was Millipora alcicornis. To the east of Booby Island hard
coral species diversity was higher but was dominated by Millipora complanata (3.2% cover, 0.5
col.m-2 density) and Montastrea faveolata (3% cover, 0.625 col.m-2 density) (Table 3.4.2). In
total 11 species of hard coral were recorded at 3m in Man-o-War Bay among the sites surveyed.
Mean gorgonian cover at 3m was 7±3% while encrusting coralline algae and sponges had
average covers of 4.8±4.7% and 3.7±4.7% respectively. Average macroalgal cover was low
making up just 1.3±1.5% of the total benthic cover.
43
Table 3.4.1:
Species cover on the reef crest (3m) at the Man-O-War Bay survey sites
Man-o-War Bay 3m
HARD CORAL
Booby Is. East
Booby Is. West
Pirate's Reef
Rest House Reef
MEAN
STD. DEV.
STD. ERROR
11.67
13.67
13.00
42.83
20.29
15.05
7.53
Agaricia agaricites
0.17
0.00
0.00
0.00
0.04
0.08
0.04
Diploria clivosa
0.67
0.00
0.00
0.00
0.17
0.33
0.17
Diploria strigosa
1.67
0.00
1.33
0.00
0.75
0.88
0.44
Madracis mirabilis
0.00
0.00
0.00
42.33
10.58
21.17
10.58
1.17
0.00
0.00
0.00
0.29
0.58
0.29
0.00
13.67
3.67
0.50
4.46
6.35
3.17
3.17
0.00
3.00
0.00
1.54
1.78
0.89
1.00
0.00
2.00
0.00
0.75
0.96
0.48
3.00
0.00
0.00
0.00
0.75
1.50
0.75
Porites astreoides
0.50
0.00
1.67
0.00
0.54
0.79
0.39
Siderastrea siderea
0.33
0.00
1.33
0.00
0.42
0.63
0.32
7.33
4.33
5.33
11.17
7.04
3.02
1.51
Briareum
0.00
0.00
0.50
3.00
0.88
1.44
0.72
Erythropodium
4.17
3.00
0.50
0.00
1.92
1.99
1.00
Gorgonian (general)
1.67
1.33
0.83
3.00
1.71
0.93
0.46
1.13
GORGONIANS
1.50
0.00
3.50
5.17
2.54
2.26
SPONGES
Pseudopterogorgia
10.67
0.50
2.67
0.83
3.67
4.76
2.38
ZOANTHIDS
3.67
54.33
32.83
3.50
23.58
24.71
12.35
Palythoa sp.
3.67
46.33
32.83
0.00
20.71
22.53
11.27
Zoanthid (general)
0.00
8.00
0.00
3.50
2.88
3.79
1.90
3.00
0.17
2.00
0.00
1.29
1.46
0.73
3.00
0.17
2.00
0.00
1.29
1.46
0.73
0.17
0.00
0.33
41.67
10.54
20.75
10.38
ENCRUSITNG CORALLINE ALGAE
11.33
4.00
4.00
0.00
4.83
4.73
2.36
52.17
23.00
39.83
0.00
28.75
22.59
11.29
MACROALGAE
44
Table 3.4.2:
Species mean density and frequency on the reef crest (3m) at Man-O-War survey sites
-2
Man-o-War Bay 3m
Species
Frequency (%)
Booby Is. East
Booby Is. West
Pirate's Reef
Rest House Reef
Booby Is. East
Booby Is. West
Pirate's Reef
Rest House Reef
0.125
0
0
0
12.5
0
0
0
Diploria clivosa
0.5
0
0
0
25
0
0
0
Diploria strigosa
0.625
0
0.875
0
50
0
50
0
0
0
0
2.375
0
0
0
100
0.25
0
0
0
25
0
0
0
Agaricia agaricites
Madracis mirabilis
0
4.625
2.75
0.375
0
87.5
62.5
25
0.5
0
1.625
0
37.5
0
100
0
0.625
0
1.25
0
37.5
0
37.5
0
0.625
0
0
0
25
0
0
0
Porites astreoides
0.125
0
1
0
12.5
0
50
0
Siderastrea siderea
0.125
0
0.375
0
12.5
0
37.5
0
0
0
0.25
1.875
0
0
25
62.5
Erythropodium
1.625
0.625
0.5
0
62.5
37.5
25
0
Gorgonian (general)
1.125
0.75
1.125
2.25
75
37.5
25
37.5
Pseudopterogorgia
0.5
0.125
1
1.75
25
0
62.5
62.5
Sponge
6.375
0.625
3.5
1.75
87.5
25
62.5
37.5
Favia fragum
0.125
0
0
0
n/a
n/a
n/a
n/a
Briareum
45
At 9m, gorgonians dominated the live benthos with an average of 13.5±8.9% cover (Table
3.4.3). Cover varied among sites though – 23% cover at Pirate’s reef, 12.6% at Booby Island
east and only 5.5% at Booby Island west. However, the 12.9±13.3% mean hard coral cover at
9m in Man-o-War Bay was largely attributable to the high hard coral percentage cover
(28.2%) recorded at Booby Island West. Montastrea faveolata dominated here – 13.3% cover
and a density of 1.125 col.m-2 (Table 3.4.4). In comparison, the other two 9m sites had low
hard coral cover, 6.5% at Pirate’s reef and 4% at Booby Island east. Overall, the total mean
live cover at 9m in Man-o-War Bay was low (about 34%) with zoanthids (2.3±2.3% mean
cover), macroalgae (2.1±2.4% mean cover), sponges (1.9±1.2% mean cover) and encrusting
coralline algae (1.4±1.3% mean cover) making little contributions.
Gorgonians again dominated at 16m with 14% cover (Table 3.4.5). The one locality surveyed
at this depth, the eastern side of Booby Island, was made up of mainly stony rubble and this
substrate type did not support a diversity of hard coral species. Only 4 species were recorded
totalling just over 4% in cover. Of the four species observed though, Millipora alcicornis had
the highest density (1.75 col.m-2) (Table 3.3.6). Macroalgal cover increased to 6.5% at this
depth as did sponge cover (3%) and encrusting coralline algae cover (1.5%) but once again
the total live cover remained at around 34%.
Live cover dropped even lower at 21m – just over 18% - with gorgonian cover making up
more than half of this (10.8% gorgonian cover) (Table 3.4.7). At this depth only 3% hard
coral cover was evident with even fewer species (3) recorded. Once again however,
Millipora alcicornis density was highest (Table 3.4.8). Sponges also occupied about 3% of
the rubbly substrate with very little colonisation recorded from encrusting coralline algae
(1% cover), zoanthids (0.3% cover) and macroalgae (0.3% cover).
46
Table 3.4.3: Species cover on the upper fore reef (9m) at Man-O-War Bay survey sites
Man-o-War Bay 9m
Booby Is. East
Booby Is. West
Pirate's Reef
MEAN
STD. DEV.
STD. ERROR
4.00
28.17
6.50
12.89
13.29
7.67
Agaricia agaricites
0.00
0.00
0.17
0.06
0.10
0.06
Colpophyllia natans
0.00
6.50
0.00
2.17
3.75
2.17
0.50
0.00
1.33
0.61
0.67
0.39
Diploria strigosa
0.67
2.67
2.00
1.78
1.02
0.59
2.00
0.17
0.17
0.78
1.06
0.61
0.50
0.00
0.00
0.17
0.29
0.17
0.33
0.83
2.67
1.28
1.23
0.71
0.00
13.33
0.00
4.44
7.70
4.44
Porites astreoides
0.00
1.17
0.00
0.39
0.67
0.39
Porites porites
0.00
0.33
0.00
0.11
0.19
0.11
Siderastrea siderea
0.00
3.17
0.17
1.11
1.78
1.03
HARD CORAL
GORGONIANS
12.00
5.50
23.00
13.50
8.85
5.11
Briareum
0.00
0.00
0.50
0.17
0.29
0.17
Erythropodium
4.50
2.17
0.50
2.39
2.01
1.16
Gorgonian (general)
3.67
3.17
15.83
7.56
7.17
4.14
Pseudopterogorgia
3.83
0.17
6.17
3.39
3.02
1.75
2.17
0.67
3.00
1.94
1.18
0.68
SPONGES
ZOANTHIDS
4.83
1.67
0.33
2.28
2.31
1.33
Palythoa sp.
0.00
1.50
0.17
0.56
0.82
0.47
Zoanthid (general)
4.83
0.17
0.17
1.72
2.69
1.56
0.00
4.67
1.50
2.06
2.38
1.38
0.00
4.67
1.50
2.06
2.38
1.38
0.17
0.33
1.17
0.56
0.54
0.31
1.33
2.67
0.17
1.39
1.25
0.72
75.50
56.33
64.33
65.39
9.63
5.56
MACROALGAE
47
Table 3.4.4: Species mean density and frequency on the upper fore reef (9m) at Man-O-War Bay survey sites
-2
Man-o-War Bay 9m
Species
Frequency (%)
Booby Is. East
Booby Is. West
Pirate's Reef
Booby Is. East
Booby Is. West
Pirate's Reef
Agaricia agaricites
0
0
0.125
0
0
12.5
Colpophyllia natans
0
0.625
0
0
50
0
0.125
0
0.25
12.5
0
25
Diploria strigosa
0.375
1
0.25
37.5
25
25
0.5
0.125
0.125
37.5
12.5
12.5
0.5
0.25
0.125
25
0
0
0.125
0.375
1.125
12.5
37.5
37.5
0
1.125
0
0
37.5
0
Porites astreoides
0
0.25
0
0
12.5
0
Porites porites
0
0.25
0
0
12.5
0
Siderastrea siderea
0
1.25
0
0
37.5
12.5
Briareum
0
0
0.125
0
0
12.5
Erythropodium
0.375
0.75
0.125
12.5
50
25
Gorgonian (general)
3.875
2.5
4.75
75
50
100
Pseudopterogorgia
1
0.125
1.5
62.5
12.5
87.5
3.75
0.625
2.5
62.5
37.5
75
Sponge
48
Table 3.4.5: Species cover on the mid fore reef (16m) at Man-O-War Bay survey site
Man-o-War Bay 16m
HARD CORAL
Booby Is. East
MEAN
4.17
4.17
Madracis decactis
0.17
0.17
2.50
2.50
1.17
1.17
Siderastrea siderea
0.33
0.33
14.00
14.00
Erythropodium
1.83
1.83
Gorgonian (general)
7.83
7.83
Pseudopterogorgia
4.33
4.33
SPONGES
3.00
3.00
ZOANTHIDS
4.33
4.33
4.33
4.33
6.50
6.50
6.50
6.50
0.83
0.83
1.50
1.50
65.67
65.67
GORGONIANS
Zoanthid (general)
MACROALGAE
Table 3.4.6:
Species mean density and frequency on the mid fore reef (16m) at Man-O-War
Bay survey site
Man-o-War Bay 16m
-2
Frequency (%)
Booby Is. East
Booby Is. East
Madracis decactis
0.125
12.5
1.75
75
0.5
50
0.125
12.5
Species
Siderastrea siderea
Erythropodium
0.5
25
Gorgonian (general)
3.875
75
Pseudopterogorgia
1.25
62.5
Sponge
3.625
87.5
49
Table 3.4.7: Species cover on the lower fore reef (21m) at Man-o-War Bay survey site
Man-o-War 21m
Booby Is. East
MEAN
3.00
3.00
Agaricis lamarcki
0.33
0.33
1.17
1.17
HARD CORAL
1.50
1.50
10.83
10.83
Erythropodium
3.17
3.17
Gorgonian (general)
7.00
7.00
Pseudopterogorgia
0.67
0.67
SPONGES
2.83
2.83
ZOANTHIDS
0.33
0.33
0.33
0.33
0.33
0.33
0.33
0.33
0.33
0.33
1.00
1.00
81.33
81.33
GORGONIANS
Zoanthid (general)
MACROALGAE
Table 3.4.8:
Species mean density and frequency on the lower fore reef (21m) at Man-o-War
Bay survey site
Man-o-War Bay 21m
-2
Frequency (%)
Booby Is. East
Booby Is. East
Agaricis lamarcki
0.125
12.5
0.25
25
0.75
50
Erythropodium
1.125
75
Gorgonian (general)
3.25
87.5
Pseudopterogorgia
0.25
25
Sponge
3.875
50
Species
50
3.5
SPEYSIDE
In Speyside the reef fringing the western coast of Goat Island and Angel Reef, was surveyed
at three separate localities, each at all four depths (Figure 2.7). At 3m, the vast majority of
the benthic structure was composed of just bare rock with a total mean live cover of only
17%. Generally low frequencies and densities of hard corals, gorgonians and sponges is a
reflection of this (Table 3.5.2). Hard corals had a low mean cover of 7.6±5.6% with 10
different species recorded (Table 3.5.1). The northern most site on Angel reef however had
14% hard coral cover, more than twice that of the other two sites i.e. in line with the jetty
(about 4% cover) and to the south of the reef (5% cover). Zoanthids, namely Palythoa
caribaeorum, occupied another 7±5.4%, on average, of the 3m zone but seemed to be more
concentrated towards the two northernmost sites with there being only 0.8% coverage at the
southern locality. A mean of about 2±1.1% represented gorgonian cover with very minimal
cover (mean 0.3±0.5%) being attributable to encrusting coralline algae.
Mean hard coral cover at 9m was relatively high (34.5±13%) and 18 different species were
recorded (Table 3.5.3). The reefs at this depth appeared healthy and diverse. The hard coral
cover at the southern site was especially high with nearly 50% of the substrate being covered
by hard corals. However, the assemblage at this site was dominated by Madracis mirabilis
(33.5% cover, 2.875 col.m-2 density) (Table 3.5.4). At the jetty site the 25% hard coral cover
was dominated by Montastrea faveolata (10.2% cover, 3.25 col.m-2 density) and at the
northern site (28.7% hard coral cover), Montastarea annularis (11% cover, 2.25 col.m-2
density) dominated. On this reef, in the upper fore reef zone about fifteen percent (15±7.7%)
of the benthos was occupied by gorgonians. Again there were variations from site to site with
the highest cover being found at the jetty site (23.8% cover). The southern and northern
surveying localities had 11.7% and 9.5% gorgonian cover respectively. The remainder of the
approximately 55% total mean live cover was shared among species in the encrusting
coralline algae (2.8±3.8% mean cover), sponge (1.9±1.7% mean cover) and macroalgae
(0.3±0.5% mean cover) categories.
51
Table 3.5.1: Species cover on the reef crest (3m) at Angel Reef, Speyside survey sites
Speyside 3m
Angel Reef North
Angel Reef Jetty
Angel Reef South
MEAN
STD. DEV.
STD. ERROR
14.00
3.83
5.00
7.61
5.56
3.21
Agaricia agaricites
0.00
0.00
0.17
0.06
0.10
0.06
Diploria clivosa
0.00
2.00
1.67
1.22
1.07
0.62
0.00
0.50
0.00
0.17
0.29
0.17
Diploria strigosa
0.00
0.17
0.50
0.22
0.25
0.15
Favia fragum
0.17
0.17
0.17
0.17
0.00
0.00
3.33
0.00
1.17
1.50
1.69
0.98
0.67
0.00
0.00
0.22
0.38
0.22
Porites astreoides
1.17
0.00
1.00
0.72
0.63
0.36
Siderastrea radians
5.00
0.17
0.00
1.72
2.84
1.64
Siderastrea siderea
3.67
0.83
0.33
1.61
1.80
1.04
HARD CORAL
GORGONIANS
1.33
3.33
1.50
2.06
1.11
0.64
Erythropodium
0.33
0.00
0.00
0.11
0.19
0.11
Gorgonian (general)
1.00
3.33
1.50
1.94
1.23
0.71
9.83
10.50
0.83
7.06
5.40
3.12
9.83
10.50
0.83
7.06
5.40
3.12
0.83
0.00
0.00
0.28
0.48
0.28
74.00
82.33
92.67
83.00
9.35
5.40
ZOANTHIDS
Palythoa sp.
52
Table 3.5.2: Species mean density and frequency on the reef crest (3m) at Angel Reef, Speyside survey sites
-2
Speyside 3m
Species
Frequency (%)
Angel Reef North
Angel Reef Jetty
Angel Reef South
Angel Reef North
Angel Reef Jetty
Angel Reef South
Agaricia agaricites
0
0
0.125
0
0
12.5
Diploria clivosa
0
0.125
0.25
0
12.5
12.5
0
0.125
0
0
12.5
0
Diploria strigosa
0
0.125
0.125
0
12.5
12.5
Favia fragum
0.125
0.125
0.75
12.5
12.5
12.5
1.125
0
1.75
37.5
0
50
0.125
0
0
12.5
0
0
Porites astreoides
0.625
0
0.625
25
0
25
Siderastrea radians
0.75
0.125
0
25
12.5
0
Siderastrea siderea
1.125
0.125
0.125
37.5
12.5
12.5
Erythropodium
0.25
0
0
25
0
0
Gorgonian (general)
0.125
0.875
0.625
12.5
50
25
0
0
0.25
0
0
0
Sponge
53
Table 3.5.3: Species cover on the upper fore reef (9m) at Angel Reef, Speyside survey sites
Speyside 9m
Angel Reef North
Angel Reef Jetty
Angel Reef South
MEAN
STD. DEV.
STD. ERROR
28.71
25.33
49.33
34.46
12.99
7.50
Agaricia agaricites
1.67
1.67
0.67
1.33
0.58
0.33
Colpophyllia natans
1.50
0.00
0.83
0.78
0.75
0.43
0.00
0.00
0.17
0.06
0.10
0.06
Diploria strigosa
8.35
2.50
3.00
4.62
3.24
1.87
0.17
0.00
0.00
0.06
0.10
0.06
Madracis decactis
0.33
0.17
0.00
0.17
0.17
0.10
Madracis mirabilis
2.00
0.00
33.50
11.83
18.79
10.85
0.00
0.50
0.00
0.17
0.29
0.17
0.00
0.00
0.17
0.06
0.10
0.06
11.02
5.00
0.33
5.45
5.36
3.09
0.00
0.00
1.17
0.39
0.67
0.39
0.00
10.17
0.00
3.39
5.87
3.39
0.00
0.17
0.00
0.06
0.10
0.06
Porites astreoides
1.17
2.50
0.50
1.39
1.02
0.59
Porites porites
0.00
0.00
0.17
0.06
0.10
0.06
Scolymia cubensis
0.17
0.17
0.00
0.11
0.10
0.06
Siderastrea radians
0.00
1.33
2.83
1.39
1.42
0.82
Siderastrea siderea
2.34
1.17
6.00
3.17
2.52
1.46
9.52
23.83
11.67
15.01
7.72
4.46
Briareum
1.34
6.50
2.67
3.50
2.68
1.55
Erythropodium
6.51
8.67
2.33
5.84
3.22
1.86
Gorgonian (general)
1.67
6.50
6.50
4.89
2.79
1.61
Pseudopterogorgia
HARD CORAL
GORGONIANS
0.00
2.17
0.17
0.78
1.21
0.70
SPONGES
0.17
3.50
2.00
1.89
1.67
0.96
ZOANTHIDS
0.00
0.83
0.00
0.28
0.48
0.28
0.00
0.83
0.00
0.28
0.48
0.28
0.83
0.00
0.00
0.28
0.48
0.28
0.83
0.00
0.00
0.28
0.48
0.28
0.33
0.00
9.50
3.28
5.39
3.11
7.18
1.17
0.17
2.84
3.79
2.19
53.26
45.33
27.33
41.97
13.28
7.67
Palythoa sp.
MACROALGAE
54
Table 3.5.4: Species mean density and frequency on the upper fore reef (9m) at Angel Reef, Speyside survey sites
-2
Speyside 9m
Species
Frequency (%)
Angel Reef North
Angel Reef Jetty
Angel Reef South
Angel Reef North
Angel Reef Jetty
Angel Reef South
Agaricia agaricites
2.625
1.125
0.875
62.5
37.5
25
Colpophyllia natans
0.125
0
0.125
12.5
0
12.5
0
0
0.125
0
0
12.5
Diploria strigosa
0.375
0.125
0.25
25
12.5
12.5
0.125
0
0
12.5
0
0
Madracis decactis
0.125
0.25
0
12.5
12.5
0
Madracis mirabilis
0.5
0
2.875
37.5
0
100
0
0.125
0
0
12.5
0
0
0.125
0.25
0
0
12.5
2.25
2.125
0.125
62.5
50
12.5
0
0.25
0.125
0
0
12.5
0
3.25
0
0
62.5
0
0
0.125
0
0
12.5
0
0.625
1
0.25
50
50
12.5
0
0
0.125
0
0
12.5
Scolymia cubensis
0.375
0.125
0
12.5
12.5
0
Siderastrea radians
0
0.5
0.375
0
25
37.5
Siderastrea siderea
0.25
0.375
0.5
25
25
37.5
Briareum
0.125
1.25
1.875
12.5
37.5
75
1
2.125
0.75
62.5
75
50
1.25
2.25
2.875
37.5
87.5
75
Porites astreoides
Porites porites
Erythropodium
Gorgonian (general)
Pseudopterogorgia
Sponge
Favia fragum
0
0.375
0.125
0
25
12.5
0.25
1.75
3.125
12.5
50
50
0
0
0.125
n/a
n/a
n/a
55
At 16m, hard coral cover was the highest category with about 24±11.2% mean cover (Table 3.5.5),
similar to 9m. Hard coral cover decreased southwards; the highest cover (36.7% cover) was on the
northern site. It fell to 18.5% at the jetty surveying site and then to about 16% at the southern
locality. On average, Diploria strigosa (6±8.8% mean cover), Madracis mirabilis (5.2±4.6% mean
cover), Agaricia agaricites (4.4±1.2% mean cover) and Porites astreoides (3.8±3.3% mean cover)
were the species of hard corals that dominated the sites at this depth. A few large colonies of
Diploria strigosa stood out at the northern survey site having 16.2% cover (0.25 col.m-2 density) at
this locality in particular (Table 3.5.6).
Gorgonian cover represented on average about 10±6.3% of the benthic cover at 16m on Angel reef
decreasing from the mean of 15±7.7% recorded at 9m. Mean encrusting coralline algae and mean
sponge cover, on the other hand, showed considerable increases with species in these categories
colonising 8.5±1.6% and 7.2±2.5% of the reef respectively. Unlike hard coral cover, sponge cover
increased steadily from north to south along Angel reef. Macroalgae, although almost negligible
(0.2±0.2% mean cover), made up the remainder of the nearly 50% total mean live cover.
Twenty one metres (21m) depth was at the vertical extent of the reef, lying at the reef/sand interface
especially at the northern and southern sites. Consequently, total mean live cover at this depth was
lower than at 9m and16m (38.6%). The paucity of suitable substrate for colonisation was reflected in
the low mean hard coral cover (Table 3.5.7). About 13.4±8% of the benthic surface was occupied by
the 12 hard coral species. The hard coral coverage at the jetty site – where the reef seemed to extend
a bit deeper – represented the only real fairly substantial amount of coverage (22.2% hard coral
cover). In addition, Agaricia sp. seemed to out-compete other hard corals at the 21m survey sites,
having the highest densities (Table 3.5.8) and representing about half of the total mean hard coral
cover.
Sponges continued their trend of increasing coverage with depth as there was 12.3±2.2% mean
coverage in this lower fore reef zone. Mean gorgonian cover declined once again to about 8±2.9%.
Encrusting coralline algae, which cannot colonise sandy substrates, had 4.7±3% mean cover and, as
was the norm with this reef, mean macroalgal cover was again minimal (0.2±0.2%).
56
Table 3.5.5: Species cover on the mid fore reef (16m) at Angel Reef, Speyside survey sites
Speyside 16m
Angel Reef North
Angel Reef Jetty
Angel Reef South
MEAN
STD. DEV.
STD. ERROR
36.67
18.50
16.17
23.78
11.22
6.48
Agaricia agaricites
4.00
5.83
3.50
4.44
1.23
0.71
Agaricis lamarcki
0.00
0.00
0.33
0.11
0.19
0.11
Colpophyllia natans
2.67
0.00
0.00
0.89
1.54
0.89
Diploria strigosa
16.17
0.17
1.67
6.00
8.84
5.10
Eusmilia fastigiata
0.00
0.33
0.83
0.39
0.42
0.24
0.50
0.17
0.17
0.28
0.19
0.11
Madracis decactis
0.17
0.00
0.00
0.06
0.10
0.06
Madracis mirabilis
9.83
0.67
5.00
5.17
4.59
2.65
0.17
0.17
0.83
0.39
0.38
0.22
0.00
0.00
0.17
0.06
0.10
0.06
0.00
1.00
0.00
0.33
0.58
0.33
0.33
0.33
0.00
0.22
0.19
0.11
Porites astreoides
1.83
7.67
2.00
3.83
3.32
1.92
Scolymia cubensis
0.00
0.17
0.00
0.06
0.10
0.06
Siderastrea radians
0.00
1.33
0.67
0.67
0.67
0.38
Siderastrea siderea
1.00
0.67
1.00
0.89
0.19
0.11
4.83
17.17
8.50
10.17
6.33
3.66
Briareum
0.00
2.83
1.83
1.56
1.44
0.83
Erythropodium
1.83
3.17
1.17
2.06
1.02
0.59
Gorgonian (general)
3.00
11.17
4.00
6.06
4.45
2.57
Pseudopterogorgia
0.00
0.00
1.50
0.50
0.87
0.50
SPONGES
4.33
8.00
9.17
7.17
2.52
1.46
MACROALGAE
0.17
0.00
0.33
0.17
0.17
0.10
0.17
0.00
0.33
0.17
0.17
0.10
6.83
0.67
1.17
2.89
3.43
1.98
HARD CORAL
GORGONIANS
7.67
7.50
10.33
8.50
1.59
0.92
39.50
48.17
54.33
47.33
7.45
4.30
57
Table 3.5.6: Species mean density and frequency on the mid fore reef (16m) at Angel Reef, Speyside survey sites
-2
Speyside 16m
Species
Angel Reef North
Angel Reef Jetty
2.5
0
Colpophyllia natans
Diploria strigosa
Agaricia agaricites
Agaricis lamarcki
Eusmilia fastigiata
Frequency (%)
Angel Reef South
Angel Reef North
Angel Reef Jetty
Angel Reef South
3.125
2.5
75
87.5
75
0
0.875
0
0
25
0.125
0
0
12.5
0
0
0.25
0.125
0.375
25
12.5
37.5
0
0.25
0.125
0
12.5
12.5
0.125
0.125
0.25
12.5
12.5
12.5
Madracis decactis
0.125
0
0
12.5
0
0
Madracis mirabilis
1
0.5
1
62.5
25
50
0.125
0.125
0.125
12.5
12.5
12.5
0
0
0.125
0
0
12.5
0
0.375
0
0
25
0
0.375
0.375
0
25
12.5
0
Porites astreoides
1
0.875
0.875
50
50
50
Scolymia cubensis
0.25
0.125
0
0
12.5
0
Siderastrea radians
0
0.625
0.25
0
25
25
Siderastrea siderea
0.125
0.375
0.25
25
12.5
25
Briareum
0
0.75
0.25
25
12.5
12.5
Erythropodium
0.75
1.375
0.5
37.5
75
50
Gorgonian (general)
1.375
3.875
1.375
50
87.5
50
Pseudopterogorgia
0.125
0
0.5
0
0
50
Sponge
2.625
4.625
3.375
87.5
100
100
58
Table 3.5.7: Species cover on the lower fore reef (21m) at Angel Reef, Speyside survey sites
Speyside 21m
Angel Reef North
Angel Reef Jetty
Angel Reef South
MEAN
STD. DEV.
STD. ERROR
11.50
22.17
6.50
13.39
8.00
4.62
Agaricia agaricites
4.00
4.17
2.17
3.44
1.11
0.64
Agaricis lamarcki
1.50
5.17
3.50
3.39
1.84
1.06
Colpophyllia natans
0.00
2.50
0.00
0.83
1.44
0.83
0.33
0.33
0.17
0.28
0.10
0.06
Madracis decactis
0.50
0.83
0.33
0.56
0.25
0.15
Madracis mirabilis
0.50
0.00
0.00
0.17
0.29
0.17
1.00
2.83
0.17
1.33
1.36
0.79
0.50
1.33
0.17
0.67
0.60
0.35
0.50
0.33
0.00
0.28
0.25
0.15
Porites astreoides
1.17
3.00
0.00
1.39
1.51
0.87
Siderastrea radians
0.00
0.33
0.00
0.11
0.19
0.11
Siderastrea siderea
1.50
1.33
0.00
0.94
0.82
0.47
5.33
11.00
7.67
8.00
2.85
1.64
Briareum
0.00
1.83
0.00
0.61
1.06
0.61
Erythropodium
0.00
2.00
0.00
0.67
1.15
0.67
Gorgonian (general)
4.17
5.67
6.17
5.33
1.04
0.60
HARD CORAL
GORGONIANS
1.17
1.50
1.50
1.39
0.19
0.11
SPONGES
Pseudopterogorgia
14.83
10.50
11.67
12.33
2.24
1.29
MACROALGAE
0.17
0.33
0.00
0.17
0.17
0.10
0.17
0.33
0.00
0.17
0.17
0.10
0.50
0.17
0.17
0.28
0.19
0.11
4.83
7.67
1.50
4.67
3.09
1.78
62.83
48.17
72.50
61.17
12.25
7.07
59
Table 3.5.8: Species mean density and frequency on the lower fore reef (21m) at Angel Reef, Speyside survey sites
-2
Speyside 21m
Species
Frequency (%)
Angel Reef North
Angel Reef Jetty
Angel Reef South
Angel Reef North
Angel Reef Jetty
Angel Reef South
Agaricia agaricites
2.25
2.375
0.75
75
75
37.5
Agaricis lamarcki
0.375
0.75
0.75
25
37.5
37.5
Colpophyllia natans
0
0.125
0
0
12.5
0
0.125
0.125
0.125
12.5
12.5
12.5
Madracis decactis
0.375
0.5
0.125
25
25
12.5
Madracis mirabilis
0.25
0.125
0
12.5
0
0
0.375
0.75
0.25
25
50
12.5
0.375
0.375
0.125
12.5
12.5
12.5
0.25
0.125
0
25
12.5
0
Porites astreoides
1
0.625
0
37.5
25
0
Siderastrea radians
0
0.25
0
0
12.5
0
Siderastrea siderea
0.625
0.375
0
37.5
25
0
Briareum
0
0.375
0
0
37.5
0
Erythropodium
0
0.625
0
0
25
0
Gorgonian (general)
1.875
2.25
1.75
62.5
75
75
Pseudopterogorgia
0.25
0.25
0.625
25
12.5
25
Sponge
4.25
3.875
3.375
100
100
100
Scolymia cubensis
0.125
0
0
n/a
n/a
n/a
60
3.6
LA GUIRA BAY
This bay is on the Atlantic side of the island and is a high energy environment with a fairly strong
current causing drift parallel to the coastline in a westerly direction. Reefs here were intermittent;
interspersed by patches of coral rubble, Palythoa beds, Thalassia patches and sand. Due to the
structures of the reefs, surveys were only conducted at one depth – 9m – as the reef sites started at
depths ranging from 4-6m and descended to about 12-15m.
Two sets of eight photoquadrats were taken at the dive site known as ‘Cove Ledge’ (Figure 2.6).
Here macroalgae had a mean coverage of 35.6±9.8% (Table 3.6.1) - making up more than half of the
total mean live cover of the area (70.4%). This macroalgae was observed overgrowing and out
competing some of the sponges in the locality. Nonetheless, sponge cover and density were still
fairly high, having averages of 15.1±0.6% cover and 8.06 col.m-2 (Table 3.6.3) respectively.
Zoanthids, namely Palythoa caribaeorum, were the only other really significant component of the
benthos, occupying a mean of 9.2±12%. Hard coral (4.7% cover), gorgonians (4% cover) and
encrusting coralline algae (1.8±0.7%) all contributed to a lesser extent to the total mean live cover.
Two sets of eight photo-transects were also conducted at the ‘Majeston’ dive site (Figure 2.6). At
this locality the gorgonian category dominated with a mean cover of 35.3±5.9% (Table 3.6.2). This
gorgonian cover however was made up almost entirely by Erythropodium caribaeorum which
colonised, on average, 34.8±6% of the benthic surface. Macroalgae also had a high mean coverage
(21.6±11.4%) with Dictyota sp. and, to a lesser extent, an unidentified reddish-gray delicate plant
with a fluffy appearance and soft texture, making up the vast majority of the macroalgal species
assemblage. Mean encrusting coralline algae coverage was much higher here than at ‘Cove Ledge’
with 10.8±2.6% mean cover. Total number of hard coral species recorded also varied between
‘Majeston’ and ‘Cover Ledge’. At ‘Cove Ledge’ 10 species were recorded whereas only half that
number was observed at ‘Majeston’. In addition, while no one species dominated at ‘Cove Ledge’,
of the 7.8±4.1% mean hard coral coverage at ‘Majeston’ 86% of this was Siderastrea siderea
colonies (6.7±3,8% mean cover). It was also noted during analysis that an average of 22.7±32% of
the S. siderea colonies here was affected by Dark Spot Disease. Mean sponge cover at ‘Majeston’
was only 3.2±1.2% making up a very small part of the almost 79% total mean live cover.
61
Table 3.6.1: Species cover on the upper fore reef (9m) at Cove Ledge, La Guira survey sites
Cove Ledge 9m
Cove Ledge 1
Cove Ledge 2
MEAN
STD. DEV.
STD. ERROR
4.67
4.67
4.67
0.01
0.00
Agaricia agaricites
0.00
0.17
0.08
0.12
0.08
Diploria clivosa
0.33
0.33
0.33
0.00
0.00
Diploria strigosa
2.33
0.00
1.17
1.65
1.17
Madracis decactis
0.00
0.83
0.42
0.59
0.42
0.00
0.33
0.17
0.24
0.17
1.00
0.17
0.58
0.59
0.42
0.00
0.17
0.08
0.12
0.08
0.00
1.50
0.75
1.06
0.75
Porites astreoides
0.00
0.33
0.17
0.24
0.17
Siderastrea siderea
1.00
0.83
0.92
0.12
0.08
4.00
4.01
4.00
0.00
0.00
Briareum
0.17
0.67
0.42
0.35
0.25
Erythropodium
1.17
1.50
1.33
0.24
0.17
Gorgonian (general)
2.67
0.17
1.42
1.77
1.25
HARD CORAL
GORGONIANS
0.00
1.67
0.83
1.18
0.83
SPONGES
Pseudopterogorgia
14.67
15.53
15.10
0.61
0.43
ZOANTHIDS
0.67
17.70
9.18
12.04
8.51
0.67
17.70
9.18
12.04
8.51
42.50
28.71
35.61
9.75
6.89
Palythoa sp.
MACROALGAE
42.50
28.71
35.61
9.75
6.89
0.17
0.00
0.08
0.12
0.08
1.33
2.34
1.84
0.71
0.50
32.00
27.05
29.52
3.50
2.48
62
Table 3.6.2: Species cover on the upper fore reef (9m) at Majeston, La Guira survey sites
Majeston 9m
HARD CORAL
Majeston 1
Majeston 2
MEAN
STD. DEV.
STD. ERROR
4.83
10.67
7.75
4.12
2.92
Agaricia agaricites
0.17
0.33
0.25
0.12
0.08
Agaricia grahamae
0.00
0.17
0.08
0.12
0.08
Diploria strigosa
0.33
0.00
0.17
0.24
0.17
Porites astreoides
0.33
0.83
0.58
0.35
0.25
Siderastrea siderea
4.00
9.33
6.67
3.77
2.67
39.50
31.17
35.33
5.89
4.17
Erythropodium
39.00
30.50
34.75
6.01
4.25
Gorgonian (general)
0.50
0.67
0.58
0.12
0.08
4.00
2.33
3.17
1.18
0.83
GORGONIANS
SPONGES
MACROALGAE
13.50
29.67
21.58
11.43
8.08
Dictyota
10.67
20.50
15.58
6.95
4.92
2.83
9.17
6.00
4.48
3.17
ENCRUSITNG CORALLINE ALGAE
12.67
9.00
10.83
2.59
1.83
25.50
17.17
21.33
5.89
4.17
63
Table 3.6.3: Species mean density and frequency on the upper fore reef (9m) at the Cove Ledge and Majeston, La Guira survey sites
-2
La Guira Bay 9m
Species
Frequency (%)
Cove Ledge 1
Cove Ledge 2
Majeston 1
Majeston 2
Cove Ledge 1
Cove Ledge 2
Majeston 1
Majeston 2
Agaricia agaricites
0
0.125
0.125
0.25
0
12.5
12.5
25
Agaricia grahamae
0
0
0
0.125
0
0
0
12.5
Diploria clivosa
0.125
0.125
0
0
12.5
12.5
0
0
Diploria strigosa
0.75
0
0.25
0
50
0
25
0
Madracis decactis
0
0.625
0
0
0
25
0
0
0
0.125
0
0
0
12.5
0
0
0.25
0.125
0
0
12.5
12.5
0
0
0
0.25
0
0
0
12.5
0
0
0
0.25
0
0
0
25
0
0
Porites astreoides
0
0.25
0.125
0.5
0
12.5
12.5
37.5
Siderastrea siderea
0.25
0.375
1.125
1
25
25
50
75
Briareum
0.25
0.375
0
0
12.5
25
0
0
Erythropodium
0.875
1.125
8.875
8.625
50
37.5
100
100
2
0.375
0.375
0.5
62.5
12.5
25
25
0
0.625
0
0
0
25
0
0
8.625
7.5
0.875
0.625
87.5
87.5
50
50
Gorgonian (general)
Pseudopterogorgia
Sponge
64
Five sets of eight photoquadrats were conducted along the length of the ‘Flying Reef’ dive site
(Figure 2.6). This reef, which is about 1.5km long, had a total mean live cover of about 48%,
lower than the other two dive sites surveyed in La Guira Bay. No major group showed
dominance on this reef (Table 3.6.4). Macroalgae had the highest coverage (12.9±5.4% mean
cover) with Dictyota sp. once again being very prolific (10.7±4.6% mean cover). The seventeen
different hard coral species recorded had a mean cover of 11.9±6% of the benthos, with
Sideratrea siderea (4.3±1.7% mean cover) and Montastrea faveolata (2±4.3% mean cover), in
combination, accounting for more than half this figure. Gorgonians also featured in similar
proportions to macroalgae with a mean cover of 10.1±2%. Sponges had an average coverage of
7.6±2.3% and consistently high densities at all the ‘Flying Reef’ surveying localities (Table
3.6.5). Encrusting coralline algae (3.7±2.4% mean cover) and zoanthids (1.9±1.4% mean cover)
however, found it hard to colonise the predominantly sand/rubble bottom.
65
Table 3.6.4: Species cover on the upper fore reef (9m) at Flying Reef, La Guira Bay
Flying Reef 9m
Flying Reef 1
Flying Reef 2
Flying Reef 3
Flying Reef 4
Flying Reef 5
MEAN
STD. DEV.
STD. ERROR
5.33
9.33
10.00
21.33
13.50
11.90
6.02
2.69
Agaricia agaricites
0.33
0.00
2.00
0.33
0.17
0.57
0.81
0.36
Agaricia grahamae
0.17
0.00
0.00
0.00
0.00
0.03
0.07
0.03
Dichocoenia stokesi
0.00
0.50
0.00
0.00
0.00
0.10
0.22
0.10
0.00
0.50
0.00
0.00
0.00
0.10
0.22
0.10
Diploria strigosa
1.33
2.83
0.00
2.00
3.33
1.90
1.31
0.59
Eusmilia fastigiata
0.00
0.00
0.17
0.00
0.00
0.03
0.07
0.03
Madracis decactis
0.00
0.17
0.50
0.00
0.00
0.13
0.22
0.10
0.17
0.00
0.67
0.00
0.17
0.20
0.27
0.12
0.00
0.17
1.17
1.83
2.33
1.10
1.02
0.46
0.00
0.50
0.00
0.00
0.00
0.10
0.22
0.10
1.50
0.00
0.67
1.67
1.00
0.97
0.67
0.30
0.00
0.00
0.33
9.67
0.00
2.00
4.29
1.92
Porites astreoides
0.00
0.00
0.17
0.00
0.00
0.03
0.07
0.03
Porites porites
0.00
0.00
0.00
0.50
0.17
0.13
0.22
0.10
Scolymia cubensis
0.00
0.00
0.17
0.00
0.00
0.03
0.07
0.03
Siderastrea radians
0.00
0.83
0.00
0.00
0.00
0.17
0.37
0.17
Siderastrea siderea
1.83
3.83
4.17
5.33
6.33
4.30
1.70
0.76
HARD CORAL
GORGONIANS
8.83
8.83
10.00
13.50
9.33
10.10
1.96
0.88
Briareum
0.00
0.00
1.00
0.17
0.67
0.37
0.45
0.20
Erythropodium
0.00
1.00
2.50
6.67
1.17
2.27
2.62
1.17
Gorgonian (general)
8.83
7.83
6.00
6.33
7.33
7.27
1.15
0.51
Pseudopterogorgia
0.00
0.00
0.50
0.33
0.17
0.20
0.22
0.10
SPONGES
8.50
7.50
9.50
3.67
8.67
7.57
2.29
1.03
ZOANTHIDS
0.50
0.50
3.33
3.00
2.33
1.93
1.36
0.61
0.50
0.50
3.33
3.00
2.33
1.93
1.36
0.61
6.50
16.00
17.33
7.50
17.00
12.87
5.39
2.41
Dictyota
5.00
14.83
13.33
6.33
13.83
10.67
4.62
2.07
1.50
1.17
4.00
1.17
3.17
2.20
1.30
0.58
0.00
0.17
0.00
0.00
0.00
0.03
0.07
0.03
2.17
3.67
4.33
7.17
1.00
3.67
2.35
1.05
68.17
54.00
45.50
43.83
48.17
51.93
9.86
4.41
Palythoa sp.
MACROALGAE
66
Table 3.6.5: Species mean density and frequency on the upper fore reef (9m) at Flying Reef, La Guira survey
-2
Flying Reef 9m
Species
Frequency (%)
Flying Reef 1
Flying Reef 2
Flying Reef 3
Flying Reef 4
Flying Reef 5
Agaricia agaricites
0.625
0
1.875
0.375
Agaricia grahamae
0.125
0
0
0
Dichocoenia stokesi
0
0.125
0
0
0.375
Diploria strigosa
Flying Reef 1
Flying Reef 2
Flying Reef 3
Flying Reef 4
Flying Reef 5
0.25
25
0
37.5
25
12.5
0
12.5
0
0
25
0
0
0
0
12.5
0
0
0
0
0
0
0
12.5
0
0
0
0.5
1.25
0.125
0.375
0.5
50
62.5
0
25
37.5
Eusmilia fastigiata
0
0
0.125
0
0
0
0
12.5
0
0
Madracis decactis
0
0.125
0.375
0.125
0
0
12.5
25
0
0
0.125
0
0.125
0
0.125
12.5
0
12.5
0
12.5
0.125
0.375
1.5
0.75
1.125
0
12.5
50
37.5
62.5
0
0.125
0
0
0
0
12.5
0
0
0
0.625
0
0.375
0.625
1
62.5
0
37.5
37.5
37.5
0
0
0.125
1.75
0
0
0
12.5
25
0
Porites astreoides
0
0
0.125
0
0
0
0
12.5
0
0
Porites porites
0
0
0
0.125
0.125
0
0
0
12.5
12.5
Scolymia cubensis
0
0
0.125
0
0
0
0
12.5
0
0
Siderastrea radians
0
0.125
0
0
0
0
12.5
0
0
0
Siderastrea siderea
0.375
1
0.75
1.375
1.25
37.5
50
37.5
50
62.5
Briareum
0
0
0.125
0.125
0.125
0
0
12.5
12.5
12.5
Erythropodium
0
0.625
1.75
1.875
0.875
0
37.5
50
75
50
Gorgonian (general)
3.625
1.75
2.875
2.875
3.875
100
87.5
87.5
75
87.5
Pseudopterogorgia
0.125
0
0.25
0.25
0.125
0
0
25
25
12.5
Sponge
4.875
5
4.75
3
3.5
87.5
87.5
87.5
75
75
67
3.7
RAPID ASSESSMENT
A rapid assessment was carried out at each survey depth at all reef sites to yield information on
Diadema antillarum presence/absence, coral disease and bleaching occurrence and recruitment.
From the surveys it appeared that D. antillarum densities remain far below the pre-mortality
estimates. This sea urchin was observed at Arnos Vale, Buccoo’s Eastern Reef, Speyside’s Angel
Reef and Flying Reef in La Guira Bay. It must be noted though that Diadema observed at Arnos
Vale were not found along the rapid assessment transects. However, in one area of the western
locality’s reef crest the numbers were very high (> 50). Here, densities were reminiscent of premortality estimates of 5 urchins.m-2 (Laydoo 1985g). A total of only thirteen (13) D. antillarum
were observed between the other remaining locations.
Rapid assessment also revealed that several coral diseases occurred throughout all the reef areas
in Tobago. Yellow Band disease affecting Montastrea, Dark Spots disease affecting Siderastrea,
Aspergillosis affecting Gorgonia, Black band disease and bleaching were all recorded. However,
these diseases were not prevalent in most locations. The exceptions to this would be Yellow
Band disease in some forereef zones of Buccoo and Culloden, and Dark Spots disease in La
Guira Bay.
The observations with regards to recruitment were also interesting. Generally, hard coral
recruitment was seen in all areas where rapid assessment was carried out except some of the reef
crest sites of Buccoo and Man-o-War Bay. However, sponge recruitment was observed far more
regularly. Of particular note were the species of scleractinian recruits. Overall, it could be said
that the major reef builders on Tobago reefs e.g. Montastrea sp., Siderastrea sp. and Diploria
sp., were observed to be recruiting. However, in comparison, far more abundant in hard coral
recruitment were non-framework builders, especially Agaricia.
68
4.0
DISCUSSION
In this study, reefs fringing Tobago do not appear to strictly adhere to the observations reported
by Gardner et al. (2003) that average hard coral cover across the entire Caribbean basin has seen
massive declines – by 80% - since the late 1970s. Conversely, the various reefs around Tobago
seem to be experiencing mixed fortunes. Mean hard coral declines were seen in some areas e.g.
Buccoo and Culloden, whereas improvements were observed in others e.g. Arnos Vale and
Speyside, when compared with the Laydoo surveys of the 1980s (Figure 4.1). The other resurveyed area, Man-o-War Bay, showed no overall trend with slight improvements in mean hard
coral cover at the mid (16m) and lower (21m) fore reef zones while there was large reduction at
the upper (9m) fore reefs. The coupled methodology between the 1985 and current study allowed
for benthic cover differences at the various depths over the last 20 years to be revealed. When
looking at the data from this point of view, the upper reef crest zones (3m) were particularly
interesting showing very significant decreases in hard coral cover in all surveyed areas except
Arnos Vale and Man-o-War Bay.
Several explanations may be proposed for the hard coral decline that took place almost island
wide at 3m. However, it is likely that different areas of Tobago have been affected by varying
synergies of factors. For example, in Culloden, where hard coral cover has seen an almost 85%
reduction at the reef crest - from 29.1% in 1985 to 4.5% in 2009 - the loss of the major reef
framework building coral Acropora palmata can be cited as the chief reason for this. In the
Laydoo (1985c) study 28% of the benthic cover here was made up A. palmata colonies.
However, it seems that inability to recover from the region wide phenomenon of white band
disease that decimated populations of this species (Laydoo 1985g) has left a void in the hard
coral assemblage at the reef crest that has yet to be filled by other hard corals. Palythoa
caribaeorum and coralline algae are now the dominant space occupiers. The situation is unlike
that found in Arnos Vale where, although A. palmata dominated the hard coral fauna in the early
1980s, post die off, Millipora complanata and to a lesser extent Diploria clivosa has filled the
void.
69
Figure 4.1:
Hard coral cover comparisons between the Laydoo (1985a-e) surveys and the current
assessments
70
A. palmata die off can also be applicable to Buccoo’s approximate 75% mean hard coral decline
in the 3m zone. Like at Culloden and Arnos Vale, this species was a major constituent of
Buccoo’s reef crests as well. The proliferation of Palythoa caribaeorum and macroalgae
however, also suggests that eutrophication has some part to play (Lapointe 2003) as hard corals
are out competed for space and/or fail to recruit. The losses of grazers e.g. Diadema antillarum which have failed to recover to densities anywhere near to pre-mortality estimates (Laydoo
1985f) - may have also exaggerated these competition effects.
Eliciting explanations for the declines at Speyside’s reef crest are not as clear cut however. In the
1980s, unlike at the aforementioned reefs, A. palmata was not a major part of the hard coral
assemblage. Species such as Porites astreoides, Siderastrea siderea and Millipora alcicornis
showed dominance instead (Laydoo 1985e). In addition, no studies in the Speyside area have
pointed to eutrophication of the waters. Diadema antillarum population has remained at low
levels since the die off but this by itself does not elicit a mechanism for scleractinian loss
(Aronson & Precht 2006). This is especially so in light of no eutrophication and low macroalgae
cover as observed in this study. As a matter of fact, it was found that the majority (83%) of the
benthic surface was just bare rock. It is therefore extremely difficult to explain the almost 57%
loss in mean hard coral cover in this zone over the last two decades.
This is especially so when, from this study, the fore reef zone (9-21m) has seen mean hard coral
cover increase. The fact that these increases have taken place tends to negate the possibility of
recruitment rates being low due to, for example, changing current patterns or inappropriate
settling surfaces. One possible explanation for the reduction though, is that the areas surveyed at
3m are where tourists on glass bottom boats are brought to snorkel. While these boats use fixed
moorings and may not anchor on the reef, other tourist related activities could have caused
sufficient disturbance that may be reflected in a decline of hard coral cover. However, the IMA
(2002) report aimed at formulating a management plan for Speyside did stress that where these
boats presently operate is deep enough to prevent damage to the reef by snorkelling and walking
on corals. This explanation therefore, is tenuous at best.
71
Like decreases in hard coral cover at Speyside’s reef crest, it is also extremely difficult to explain
the opposite - increases in cover at various reef zones surveyed around the island. The reef crest
and fore reefs of Arnos Vale, the entire fore reef of Speyside and the mid and lower fore reefs of
Man-O-War Bay all showed mean hard coral cover increase. In light of the ever increasing
negative pressures on Tobago’s marine environment through a myriad of factors such as
population increases, rampant coastal development, changing watershed and land use that
promotes terrestrial run off, climate change and its associated impacts and increased tourism
volume and artisanal fishing effort (Mora 2008; Burke & Maidens 2004), improvements in
scleractinian cover on reefs is certainly not in keeping with the almost ubiquitous worldwide
trend of reef decline. This is especially so given the fact that little to no safeguarding measures
e.g. establishment of Marine Protected Areas (MPA) or Coastal Zone Management Plans, have
been instituted to protect reefs in those areas where hard coral cover increase has been evident.
On the contrary, Buccoo, where the only MPA in the country exists, has seen declining fortunes
in some areas.
Therefore, at the risk of sounding pessimistic, it is unlikely that the improvements reflected in
the data have occurred in reality. Rather, the data has to be interpreted with caution. It appears
more feasible that better technology e.g. higher resolution coloured photographs and the
application of the user friendly CPCe program, has made the present study more accurate. The
limitations placed on researchers in the 1980s may have led to an underestimation of hard coral
cover and as such, a pseudo improvement in some areas when comparing the both results from
the both time periods. The large data gap that exists in terms of time elapsed between the 1985
study and similar assessments like this one only serves to increase the level of uncertainty when
trying to make comparisons and draw conclusions. If hard coral cover was underestimated in the
Laydoo (1985a-e) surveys however, it would suggest that the declines observed in areas such as
Buccoo and Culloden have been even more drastic.
In South-west Tobago, land use change and coastal development has been freely ongoing for
several decades. Many commentators over the years have offered cautionary words about this
situation as it pertains to Buccoo Reef’s survival and resilience (Goreau 1967; Kenny 1976;
Laydoo 1985a; IMA 1994). Nonetheless, cumulative terrestrial inputs such as fertilizer from golf
72
courses and agriculture, sewage from hotel and domestic wasters and sediments in run off from
impacted catchments and coastal construction, which all negatively affect water quality and reef
health, provide the main, plausible explanations for the observed hard coral decline on Buccoo
(Wilkinson 2008).
To a lesser extent, the influence of fairly novel challenges may also be cited. For example,
Buccoo was severely affected by coral bleaching in 1998 and 2005 (O’Farrell & Day, 2005).
Although the majority of corals recovered1 high incidences of disease e.g. Yellow Band disease
observed in the current study at the upper fore reef in some surveyed areas of Buccoo, may be as
a result of increased susceptibility due to bleaching. Yellow Band disease is known to cause
partial to total colony mortality and is considered to be one the most widespread and damaging
coral diseases (Cervino et al., 2001).
Ironically, deleterious pressures on Culloden’s reefs seem to be less than that of Buccoo’s but
hard coral cover decline from 1985 to now has been far more precipitous. Whereas Buccoo had a
mean scleractinian decrease of 6.2% over the entire reef crest to lower fore reef area, Culloden’s
mean decrease was 18.1% over the same zones. In the 1980s the relatively pristine, undisturbed
coastal and marine environment of Culloden actually led Laydoo to suggest that this area could
have been used as a control site in monitoring environmental impacts at other reef localities in
Tobago (Laydoo 1985h). Today, however, the coast of Culloden and the surrounding region still
remains largely undeveloped so associated anthropogenic impacts should still be minimal –
definitely far less than in Buccoo – yet coral health has deteriorated more rapidly. A thorough
investigation into water circulation in this area needs to be conducted though, to determine if
pollutants may be coming from other areas of the coast.
It is known however, that Culloden was badly affected by bleaching in 2005 with more than 85%
of hard corals being affected (O’Farrell & Day, 2005). However, like at Buccoo, the majority of
corals recovered1. Montastrea faveolata – identified as Montastraea annularis in the Laydoo
1985 studies as several distinct Montastrea species were, in that time, considered just different
growth forms of M. annularis (Weil & Knowlton 1994) – has always been, and remains, the
1
www.buccooreef.org/coral_bleaching.html
73
most dominant scleractinian on the fore reef slopes of Culloden (Laydoo 1985c). However, as
mentioned earlier, in the results of the present survey a high incidence of infection of M.
faveolata by Yellow Band disease was noted. It is therefore being postulated that disease has
been responsible for the waning hard coral health of Culloden. If this is indeed the case, declines
might have been relatively recent. The lack of regular surveys over the last two decades
however, precludes any declaration being made with respect to the nature of the decline.
It is interesting to note that Buccoo and Culloden, perhaps the only two real coral reef systems
studies (where aragonite structures have been built up over time) – the other areas can be more
considered as coral assemblages growing on rocks – are the chief areas exhibiting declining hard
coral cover. Perhaps the fates of these two ‘true reefs’ on the leeward coast of Tobago are
intertwined. Conducting paleo-reef studies may be able to shed some light on this theory.
Generally, in all the reef areas surveyed, far more hard coral species were recorded in the present
study’s photoquadrat analyses when compared to those recorded in Laydoo’s (1985a-e) analyses.
This was so even though he applied 450 random points to each 1m2 photoquadrat as opposed to
the 75 that were used in this CPCe assisted analytical method. It is unlikely that these additional
species are a reflection of increasing diversity on Tobago’s reefs as most were identified and
recorded in previous checklists done via visual surveys (Kenny 1976; Ramsaroop 1981; Laydoo
1985a-e; Laydoo 1990; IMA 1990; IMA 2002). It is perhaps, therefore, yet another illustration of
improved technology and fewer limitations yielding more accurate results in this study.
There are a few other noteworthy points to be made. Firstly, it appears that Madracis mirabilis
was misidentified in the Laydoo surveys as Madracis decactis in some areas where its coverage
was high e.g. Angel Reef’s upper and mid fore reef, Speyside and Rest House Reef’s reef crest,
Man-o-War Bay. It was recorded by Ramsaroop (1981) as Madracis asperula when he was
formulating his checklist of the coral fauna found in Man-o-War Bay. Nonetheless, the
specimens in this present surveys’ photoquadrats unmistakably match the examples of the yellow
pencil coral (Madracis mirabilis) found in Humann (1998).
74
Secondly, the loss of cover from the reef building coral Siderastrea siderea is very noticeable
between the 1985 surveys and now (Table 4.1) Buccoo’s fore reef slopes went from being S.
siderea dominated to M. faveolata dominated. Here the upper fore reef experienced a 92%
decrease in average cover and both the mid and lower fore reefs an 89% average cover decrease.
At Culloden’s mid fore reef there was an average decrease of 63%. A 93% mean decline was
seen at Man-o-War Bay’s upper fore reefs and a 58% mean decline was seen at the reef crest of
Angel Reef, Speyside. Conversely, no significant S. siderea increases were observed anywhere.
It should be noted however that it is not immediately clear whether Laydoo (1985 a-e)
differentiated between S. siderea and S. radians in his surveys. If he did not, this may over
exaggerate the extent of S. siderea decline. That being said however, in these present surveys S.
radians did not really have high percentage coverage in any of the survey locations and thus the
S. siderea decline is still drastic.
Again, the lack of regular, continuous surveying over the last two decades makes accurately
commenting on the nature of this decline impossible. The same could be said for proposing a
reason for the decline. However, Dark Spots disease which, during rapid assessment, was
observed on Tobago reefs but was not prevalent, bleaching, or some other disease may be
possible factors. Coral Cay Conservation has been monitoring Tobago reefs since 2005, after the
bleaching event. They too have noticed significant loss of S. siderea, at 7m and 12m, since then
and suggest that bleaching (70% of S. siderea were bleached during the event) and subsequent
death of colonies is a major contributor to what is being observed in their surveys (pers. comm.
Jan-Willem van Bochove). S. siderea losses were the only major change in community structure
observed on the surveyed reefs between 1985 and now.
75
Table 4.1:
Siderastrea siderea percentage cover change between the Laydoo (1985 a,b,c,e) surveys
and the present surveys
Survey Locations
3m Speyside
16m Culloden
9m Buccoo
16m Buccoo
21m Buccoo
9m Man-o-War Bay
Mean Siderastrea siderea % cover
1985
2009
3.87
7
5.7
27.33
10.75
16.2
1.61
2.58
0.46
2.89
1.17
1.11
% Reduction in
cover
58
63
92
89
89
93
Thirdly, the quantitative surveys conducted on the reefs in La Guira Bay are the first of its kind.
The qualitative description given of Flying Reef in IMA (1990) i.e. a fore reef slope community
dominated by gorgonian, with stony corals being ubiquitous and sponges common, does not
seem to have changed much. From the data though, the percentage of bare or exposed substrate
here has increased since 1990. Also, as stated in IMA (1990), and supported by this current
study, the coral species diversity in La Guira Bay seems to be similar to that recorded around the
other reefs of Tobago.
However, further visual surveys would elicit a more detailed species checklist than that found in
the IMA (1990) report. Surveys should be carried out to update the ichthyofaunal species lists as
well. Interestingly, the rapid assessment surveys did reveal a fairly high incidence of Dark Spots
disease affecting S. siderea colonies in La Guira Bay. As mentioned earlier, for reasons
uncertain, this species has seen a drastic fall in cover on some Tobago reefs over the last two
decades. In addition to this, although Flying Reef is by far the most popular dive site in this area,
the exceedingly high macroalgal cover recorded, especially at Cove Ledge, and to a lesser extent,
Majeston, is cause for concern as these areas are also frequented by divers.
Lastly, this study was designed to repeat, where practicable, Laydoo (1985a-e) methodologies so
that one of the main objectives i.e. comparison of datasets, could be more readily carried out.
One limitation of this however, is that for fore reef zones that are extensive and gently sloping where average reef depth remains the same over large distances - eight photoquadrats at, for
76
example, 9m or 16m, may not be sufficient to capture the true essence of what exists at that
depth. This holds true for reefs at Culloden and Buccoo for instance. It is a concern that, for
Buccoo especially, although an approximate 6% mean hard coral decline was observed over fore
reef zones here, the aforementioned limitation may have led to an underestimation of this
decrease. Richard Hubbard (pers. comm.), who has been diving in this area since the 1980s, has
painted a grimmer picture of hard coral loss from then to now. In the future therefore, when these
assessments are carried out again, perhaps multiple photo-transects should be carried out at some
of the survey sites e.g. Western, Northern and Outer reefs, Buccoo and Culloden East and West,
to glean more adequate insight as to what can be found at these locations.
77
5.0
CONCLUSIONS
Results from the assessment of the various areas around Tobago show the fates of their reefs to
be mixed in terms of comparative extent of hard coral cover over the last two and a half decades.
Mean hard coral declines were seen in some areas e.g. Buccoo and Culloden, whereas
improvements were observed in others e.g. Arnos Vale and Speyside reefs. Reefs in Man-o-War
bay, showed no overall trend with slight improvements in mean hard coral cover at the mid and
lower fore reef zones while there was a large reduction in cover at the upper fore reefs. Surveys
carried out at the reefs in La Guira bay were novel and thus comparisons could not be made.
However, macroalgae cover is of major concern especially at the Cove Ledge dive site.
When making comparisons between the 1985 surveys and those done in this study however, the
data has to be interpreted with caution. It is possible that better technology e.g. higher resolution
coloured photographs and the application of the user friendly CPCe program, has made the
present study more accurate. Limitations placed on researchers in the 1980s may have led to an
underestimation of hard coral cover. This therefore may paint a false picture, one where
improvements in hard coral cover may have been shown when in fact there were none. In
addition, where declines were apparent, the situation may be much worse.
To prevent a similar situation of uncertainty from occurring in the future as well as to further
track changes in the dynamic Tobago reef environments e.g. the decline, or alternatively,
recovery of species such as Sideratrea siderea and Diadema antillarum, it is being suggested
that monitoring be ongoing. Surveys of this kind should be carried out by the IMA on at least, a
3-4 year basis.
In addition to this, a few other projects, pertaining to Tobagonian reefs, are being proposed. The
first is a high resolution examination of the stability of the coral community structure and
demography (recruitment, growth, survivorship etc.) of major coral reef organisms on a reef with
a high degree of anthropogenic impact (Buccoo Reef) and one that is less impacted (Culloden
Reef). It is expected that, through this project, community structure will be assessed by means of
78
surveys of the same permanent transects/quadrats in order to reveal and document changes and
provide insight into the dynamics of coral reef communities.
A second proposed project entails using a Nitrogen loading model to determine the natural load
of nitrogen to the Bon Accord Lagoon and Culloden Bay, to identify the major land uses that
contribute to the nitrogen loads in these areas and to estimate the nitrogen retention provided by
the different components of the watersheds e.g. forest, wetland etc. This research could feed into
management guidelines for an Integrated Coastal Zone Plan for Buccoo Reef and Culloden Reef
especially as it relates to alleviating eutrophication of the coastal waters.
A third project was alluded to in earlier discussion – a paleo-reef study to garner historical
insights from Tobago and Trinidad’s reefs. It is anticipated that cores of old dead reef, recent
dead reef as well as modern corals from locations such as Buccoo and Culloden in Tobago and
Guayaguayare, Salybia and Chaguaramas in Trinidad will be analysed to age reefs and
reconstruct past environmental conditions.
79
6.0
REFERENCES
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and Economic Statistic. St Micheal’s, Barbados.
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Glynn, P. W. 1997. Bioerosion and coral reef growth: a dynamic balance. In Life and Death of
Coral Reefs. Edited by C. Birkeland. New York: Chapman and Hall.
Goreau, T.F. (1967) Buccoo Reef and Bon Accord Lagoon, Tobago. Observations and
recommendations concerning the preservation of the reef and its lagoon in relation to
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investigations and water quality monitoring. Chaguaramas: Institute of Marine Affairs.
80
IMA (2002) Technical report for the formulation of a management plan for the Speyside Reefs
Marine Park - Bio Physical. Chaguaramas: Institute of Marine Affairs.
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reefs in Jamaica and southeast Florida. Limnology and Oceanography 42, pp. 1119-1131.
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reef monitoring on fringing reefs of Tobago: Chemical and ecological evidence of
sewage driven eutrophication in the Buccoo Reef Complex. Proceedings of the Fiftyfourth annual Gulf and Caribbean Fisheries Institute, pp. 457-472.
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Report. Chaguaramas: Institute of Marine Affairs.
Laydoo, R.S. (1985 b). Coral reefs at Man-O-War, Tobago. Chaguaramas: Institute of Marine
Affairs.
Laydoo, R.S. (1985 c). Coral reefs at Culloden Bay, Tobago. Chaguaramas: Institute of
Marine Affairs.
Laydoo, R.S. (1985 d). Coral reefs at Arnos Vale, Tobago. Chaguaramas: Institute of Marine
Affairs.
Laydoo, R.S. (1985 g). In-situ observations of Diadema antillarium mass mortality in Tobago,
West Indies. Chaguaramas: Institute of Marine Affairs.
Laydoo, R.S. (1985 e). Coral reefs at Speyside, Tobago. Chaguaramas: Institute of Marine
Affairs.
Laydoo, R.S. (1985 f). Inference of a ‘White Band’ epidemic in the elk-horn coral Acropora
palamata (Lamarck) populations in Tobago, West Indies. Institute of Marine Affairs.
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Chaguarams: Institute of Marine Affairs.
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Caribbean Marine Studies 1, pp. 29-36.
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Lessios, H.A., Robertson, D.R. and Cubit, J.D. (1984) Spread of Diadema mass mortality
through the Caribbean. Science 226, pp. 335-337.
Littler, M. M., Littler, D. S. and Lapointe, B. E. (1992) Modification of tropical reef community
structure due to cultural eutrophication: the southwest coast of Martinique. Proceedings
of the 7th International Coral Reef Symposium 1, pp. 335-343.
Mora, C. (2008) A clear human footprint in the coral reefs of the Caribbean. Proceedings of the
Royal Society B 275, pp. 767-773.
O’Farrell, S. and Day, O. (2005) Report on the 2005 coral bleaching event in Tobago – Part 1:
Results from Phase I survey. Buccoo Reef Trust and Coral Cay Conservation, Tobago.
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associated reef fisheries. Proceedings of the 5th International Coral Reef Symposium 6,
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Ecological Progress Series 62, pp. 185-202.
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82
7.0
ACKNOWLEDGEMENTS
I would like to thank the following persons for their assistance in undertaking this project.
Fellow Researchers Dr. Rahanna Juman, Mr. Richard Hubbard and Dr. George Warner for their
advice and guidance throughout. Technicians Mr. Addison Titus, Mr. Jonathan Gomez and Mr.
Russell Rajnauth in carrying out field surveys. Boat Captain Mr. Allerson Small and his crew,
Launch Engineer Mr. Hayden Branche and Deckhand Mr. Ronald Robinson. Maps in this report
were produced by Mr. Deanesh Ramsewak and Mr. Sean Padmanabhan and Mrs. Charmain
Pontiflette-Douglas who aided in formatting this report.
83

coastal conservation project an assessment of the coral reefs of

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