The coral reefs located off the north coast of the Jamaican mainland are some of the best and most studied reefs in the world. Coral reefs of Pedro Bank, Jamaica were assessed in March, 2012 as part of the KSLOF Global Reef Expedition using a modified Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocol. The main objectives were to: 1) characterize the distribution, structure and health of coral reefs; and 2) evaluate the population status of commercially important reef fishes and invertebrates. This work was conducted to assist in characterizing coral reef habitats within and outside a proposed fishery reserve, and identify other possible conservation zones. Within 20 reefs, live coral cover ranged from 4.9% to 19.2%. Coral communities were dominated by small corals (esp. Agaricia, Porites and Siderastrea) although many sites had high abundances of large colonies of Montastraea annularis and M. faveolata, and these were generally in good condition. A single area, within the proposed fishery reserve, had extensive Acropora cervicornis thickets, and several shallow locations had small, but recovering A. palmata stands. Macroalgal cover at all sites was relatively low, with only three sites having greater than 30% cover; crustose coralline algae (CCA) was high, with eight sites exceeding 20% cover. Fish biomass at all sites near the Cays was low, with a dominance of herbivores (parrotfish and surgeonfish) and a near absence of groupers, snappers and other commercially important species. While parrotfish were the most abundant fish, these were all extremely small (mean size= 12cm; <4% over 29cm), and they were dominated by red band parrotfish (Sparisoma aurofrenatum) followed by striped parrotfish (Scarus iseri). While coral communities remain in better condition than most coastal reefs in Jamaica, intense fishing pressure using fish traps (main target species: surgeonfish) and hookah/spear fishing (main target: parrotfish) is of grave concern to the future persistence of these reefs. The proposed fishery reserve encompasses some of the best coral reef habitat near the Cays, but this MPA should be expanded to encompass other habitats and MPAs should be considered for bank reefs at the northwestern end, as well as Banner Reef and Blowers Rock.
Key words: Pedro Bank, Jamaica, coral reef health, fish community structure, marine protected areas.
Resumen
Los arrecifes de coral ubicados ]]>
Agaricia, Porites y Siderastrea), aunque en varias localidades se presentó una mayor abundancia de colonias grandes de M. annularis y M. faveolata, y estos se encontraban por lo general en buenas condiciones. Dentro de la ]]>
A. cervicornis, y varias localidades someras presentaron pequeños fragmentos de A. palmata, pero en proceso de recuperación. La cobertura de macroalgas en todas las áreas fue relativamente baja, solo tres lugares presentaron más de un 30%; la cobertura de algas coralinas calcárea ]]>
Sparisoma aurofrenatum), y por el pez loro de rayas (Scarus iseri). Mientras que las comunidades de coral permanecen en mejor condición que muchos de los arrecifes costeros de Jamaica, existe una intensa presión pesquera usando trampas de pesca (principal objetivo: cirujanos) y de compresores de aire (hookah)/ pesca con arpón (principal objetivo: pez loro) es preocupante, y compromete la persistencia y el futuro de estos arrecifes. La reserva marina (MPA) ]]>
Palabras clave: Banco de Pedro, Jamaica, salud del arrecife de coral, estructura comunitaria de peces, ]]>
The coral reefs located off the north coast of the Jamaican mainland are some of the best and most studied reefs in the world (Hughes, 1994). In contrast, very few studies have been conducted on the banks located off the south coast of Jamaica. The first and only comprehensive coral reef assessment was ]]>
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Since the mid-2000s, conservation agencies in Jamaica have been working to implement the Pedro Bank Coral Reef Management Project. This project has included biological and socioeconomic assessments, feasibility studies, and efforts to control and minimize overfishing and degradation of coral reefs and coral cays due to unsustainable human settlement. A primary goal has involved the development of a zoning strategy, including the adoption of a fishery reserve off southwest Cay. To help inform constituents of the value of these resources and the benefits that would ensue through establishment ]]>
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Materials and Methods
Study sites: Pedro Bank is a submerged bank rising abruptly from about 500m depth. It is located about 58km off Jamaica at its closest point (Portland Point), and roughly 98km from Kingston, Jamaica. It extends over an area of 8 040km2 and has a circumference of roughly 590km. Much of the bank is relatively shallow (about 10-24m depth) with extensive seagrass beds, rubble and sandy habitats, and scattered patch reefs. The bank gradually deepens in a NW direction. The south and southeast sides of the bank face into the Caribbean current and have the best developed reefs. The coral reef community structure was assessed at 20 sites along the S/SE sides, within 18 fore reef locations and two patch reefs (Table 1). At each site, data were collected on benthic community ]]>
Benthic cover: Cover of benthic organisms was estimated using a minimum of six 10m long transects per site (158 transects total) and one to three 10m x 1m photo-transects. The organism and substrate type were recorded every 10cm for a total of 100 points per transect. Substrates were categorized as hard-ground, ]]>
Coral: Coral species diversity, ]]>
m2 area, 4cm or larger in diameter, was identified, measured (length, width and height) and assessed. Visual estimates of tissue loss were recorded for each colony using a 1m bar marked in 1cm increments for scale. If the coral exhibited tissue loss, estimates of the amount of remaining tissue and percent that died were made based on the entire colony surface. Tissue loss was categorized as recent mortality (white ]]>
The abundance of recruits (corals smaller than 4cm) was assessed using a minimum of five 0.25m2 quadrats ]]>
Motile invertebrates: The abundance of large motile invertebrates (crustaceans, molluscs and echinoderms) was quantified using random circular plots, each 10m diameter (total ]]>
m2), with 1-4 plots assessed per reef. One diver would extend a 10m line from a central point and then swim slowly in a circle while a second diver would record the numbers of each species of invertebrate seen within the plot. Additional roving surveys were undertaken to assess presence of invertebrates in cryptic areas, including ledges and caves. Invertebrates were also counted and recorded within coral belt transects. ]]>
Reef fish: The reef fish assemblage (approximately 70 species) was quantified within a minimum of six 30 x 2m belt transects per site (187 transects total). All species were identified and their size was estimated to the nearest 5cm using a T-bar marked in 5cm increments for scale. The assessment focused on species that are ecologically relevant to the health of reefs and also important for commercial or recreational fisheries, with emphasis on herbivores, invertivores and larger piscivores. Roving surveys were ]]>
Data analysis: All data were initially entered into Microsoft Excel spreadsheets with PRIMER software used for graphical and comparative analysis. Species diversity, richness and evenness was calculated using the Shannon – Weiner index (H`): [H` = - Σi pi (log pi)]; Margalef’s species richness (d): d = (S - 1)/ log (N), where S= number of species; N = number of ]]>
Clustering of benthic data, coral composition and fish biomass/abundance by site was examined using multi-dimensional scaling (MDS) followed by similarity profiles (SIMPROF) analysis to determine the factors that contribute most to a particular grouping. Individual contribution (e.g. fish taxa, fish ]]>
A Reef Health Index (RHI) was calculated for each dive site using seven specific biological indicators assessed during the field surveys. The grades were calculated by converting the mean for each indicator into a rank of 1 ]]>
Coral Index, comprised of coral cover, coral disease prevalence and coral recruitment; and a Reef Biota Index, comprised of a macroalgal index, herbivorous fish abundance (parrotfish and surgeon fish only), commercial fish abundance (grouper and snapper only), and Diadema abundance. The ranked scores of the three Coral measures and the four Reef ]]>
measures and these two sub-indices were then averaged to calculate an integrated reef health index. Threshold values for each rank were based on data ranges presented in the Healthy Reef Initiative report (HRI, 2008).
Results
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Benthic community structure: Within coral reef habitats, over 60% of the bottom was covered by algae, most of which was fleshy and erect coralline macroalgae (31%) and crustose coralline algae (18%). Live coral cover ranged from 4.9% (PB-01) to 19.2% (PB-20). Mean cover of other invertebrates was 14.5%, while 12.3% of the bottom consisted of uncolonized substrate (sand, rubble or hardground); 1% was dead coral (Fig. 1). Sites contained a total of 33 ]]>
Agaricia, Siderastrea, Porites and the
Montastraea annularis complex, respectively (Fig. 2). Most corals were small (mean diameter= 20cm), with 30% of all colonies 21cm or larger and 2% of the corals 100cm or larger (Fig. 3). The only corals with a mean diameter that exceeded 20cm were the M. annularis complex, M. cavernosa, Colpophyllia natans, Dendrogyra cylindricus, Acropora palmata and A. cervicornis (
Fig. 4). A single taxon, M. faveolata, was dominated by colonies that exceeded 50cm. All corals exhibited a very low percent partial mortality (mean= 10%) and virtually no recent or transitional mortality (<1%). The greatest amount of partial tissue loss was observed in the largest ]]>
C. natans (20%), M. annularis (22%) and M. faveolata ]]>
Fig. 5). Coral recruits were dominated by S. siderea (27%), P. astreoides M. cavernosa (7%), Favia fragum (6.5%) and Meandrina meandrites (5.8%), with all species (pooled) occurring at a density of 3.3/
m2 (Fig. 6).
Reef fish communities: Reef fish populations exhibited a fairly low diversity (116 species), abundance (65 fish/100
m2), size (mean=13cm) and biomass (9 430g/100m2). Populations were dominated by herbivores, with parrotfish occurring at the highest density (25fish/100m2). Sparisoma aurofrenatum
(redband parrotfish) and Scarus iseri (striped parrotfish) were most abundant, but all parrotfish were exceptionally small (mean=12cm total length) including terminal phase fish (18% were 21-29cm and 3% were 31-40cm). Other abundant species were surgeonfish (11fish/100m2), wrasses (9fish/100m2), and grunts (6fish/100m2); most other functional groups had a density of <1 fish/100m2.
All species of fish were small; over 78% were less than 20cm and only 3.5% were over 30cm. Overall biomass of reef fishes was low; herbivores had the greatest biomass, at 5 500g/100m2 followed by invertivores (2 965g/100m2). Triggerfish contributed most to the biomass of invertivores, with the abundance of these species increasing with distance from the Cays. Many functional groups of fishes were rare or absent including all snappers, large serranids (populations consisted only of hinds and graysby), barracuda, morays, grunts, and angelfish. Commercially significant species showed the lowest numbers and biomass overall, emphasizing the heavy fishing pressure occurring on Pedro Bank.
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Although fish populations remain healthier on Pedro Bank than that observed off mainland Jamaica, fish community structure has shown substantial changes since 2 005 surveys (Fig. 7). Most importantly, the abundance and biomass of surgeonfishes has declined quite substantially. Parrotfish abundances are slightly higher than that recorded in 2005, but the biomass for the two time periods is virtually the same, suggesting the average size of individual fish has declined over this period. In sites closest to the ]]>
Motile invertebrates: Commercially important (Panulirus, Strombus) ]]>
(Diadema, sea cucumbers, large crabs, octopus) were present in extremely low abundances. Queen conch were observed on 9 reefs at a very low density, with slightly higher abundances in six locations (0.1animal/m2). This is not necessarily indicative of the population size on Pedro Bank, however, as key Strombus habitats were not examined. Lobsters were rarely observed on reefs, occurring at 12 sites at densities of 2lobster/100m2); much higher numbers were seen in landings examined on shore. Prominent Diadema populations occurred in two locations (12-20/100
m2); low densities (<0.5/100m2) in other sites suggests they have shown limited recovery since the die-off in the 1980s.
Drivers of community structure: With exception of a few sites, dominant taxa were similar in ]]>
Fig. 8). Sites also subdivided into eight groups based on the contribution of different fish taxa to biomass, with groupings differentiated mostly due to relative amounts of parrotfish, surgeonfish and/or triggerfish. Most other variables were fairly ]]>
Diadema abundance were uniformly low among all sites. Analysis of Similarity (ANOSIM) testing did not reveal any significant relationships between coral abundance and macroalgal cover (R2=0.155, p=0.161); coral abundance was related to fish biomass (all species pooled), but the R-value was very low (R2=0.249; p=0.006). Fish abundance (all species pooled) was not related to coral cover ]]>
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Resilience and health of reefs: The sites examined in this study exhibited Reef Health Index (RHI) scores that varied from 1-3 (critical to fair condition) for seven parameters (coral cover, coral recruitment, coral disease, fleshy algae biomass, herbivore abundance (Diadema, parrotfishes and surgeonfishes), and ]]>
Fig. 9).
Discussion
Pedro Bank is a unique area that ]]>
Acropora palmata framework and the largest ]]>
A. cervicornis found on Pedro Bank. Other important high relief coral habitats and seagrass beds were adjacent but outside of the reserve boundaries and around Banner Rock, Blowers Rock and D and C shoal.
In all locations, coral cover was ]]>
Agaricia and Porites) as well as Siderastrea, Diploria, and Meandrina. Of note were several populations of larger ]]>
Montastraea annularis (complex), as well as stands of Madracis mirabilis, and numerous large Dendrogyra colonies. Montastraea annularis (complex), once the most important ]]>
M. annularis tissue remnants. On ]]>
M. annularis and M. faveolata colonies were completely ‘live”. Very little disease, bleaching and recent mortality was noted on these species. Extensive Acropora framework with scattered live colonies surrounded many of the cays and emergent shoals, and small patches of A. cervicornis were found on many of the deeper reefs (10-30m depth). Acroporid corals have become rare in most Caribbean locations as a result of white band disease outbreaks in the 1980s, recent bleaching ]]>
One of the most positive findings among the stony corals examined on Pedro Bank was the low level of partial mortality. AGRRA surveys that have been conducted throughout ]]>
M. annularis complex and other larger massive corals. On Pedro Bank most colonies were intact; partial mortality was usually ]]>
M. annularis (complex) showed about 20% partial mortality. The presence of healthy, undamaged colonies may be an indication of higher resilience, better environmental conditions and a greater potential for successful reproduction, as corals have not been reduced below the minimal size threshold necessary for gametogenesis (Szmant-Froelich, 1985; Szmant, 1991). ]]>
The benthos also appeared to be in fairly good condition. Even though Diadema were rare in most locations, and cover of macroalgae exceeded the cover of living coral, there was a general impression that fleshy macroalgae was less abundant than that reported from many other Caribbean localities (Lang 2003). The substrate had a prominent cover of crustose coralline algae, with small patches of erect coralline algae and some macroalgae, most of which ]]>
The largest concern to Pedro Bank reefs is overexploitation of the fishery resources. Exploitation of ]]>
Intensive fishing pressure appears to have affected most species as all reefs had a fairly low biomass of fishes and many key species were extremely rare or absent. The current targets of the fishery appeared to be two families of herbivores which made up the bulk of the catch, scaridae and acanthuridae. Very few schools of surgeonfish were documented and individuals were small ]]>
Two main fishery approaches are now undertaken on Pedro Bank, trap (pot) fishing and spearfishing using hookah (Aiken & Kong, 2000; Gustavson, 2002). The Antillean z-traps ]]>
At this time, the overall condition of Pedro Bank’s coral reefs remains far better than most reefs off mainland Jamaica, but these reefs are at a tipping point. The establishment of the South West Cay Special Fishery Conservation Area is a key step forward in conservation of Pedro Bank’s coral reef resources, as it will allow fish to grow larger, potentially producing ]]>
m2, is far too small to adequately protect fishery resources as this represents <0.1% of the total area (9 247km2; Zenny, 2006) of Pedro Bank. Furthermore, the increasing fishing effort and destructive types of fishing are unsustainable and are likely to trigger deleterious changes to the reefs. Additional conservation measures that emphasize an expanded network of protected areas may help maintain and restore Pedro banks precious coral reefs.
Recommendations
Significant benefits could be achieved by expanding the boundaries of the newly established Fishery Reserve such that it encompasses extensive and healthiest high relief Montastraea dominated coral habitat found to the south and west, and it ]]>
Montastraea faveolata and M. annularis colonies intermixed with extensive stands of
Porites porites, A. cervicornis patches, large colonies of Dendrogyra cylindricus and high relief coral bommies in deeper sandy areas, extensive Acropora ]]>
Diadema seen on Pedro Bank, the highest diversity of fish families, and a high biomass of fish composed of schools of grunts, parrotfishes and surgeonfishes. Blowers Rock is also another candidate MPA site. It had the largest high-relief Acropora palmata framework seen on Pedro Bank with extensive patches of live A. palmata. A very unusual Montastraea dominated reef was also ]]>
Montastraea faveolata colonies, the largest seen on the bank. Because these areas are east (and upcurrent) of the inhabited Cays and the Fish Sanctuary, the endangered corals that occur on these reefs (
Montastraea and Acropora) could serve as seed stock for other areas on the bank to the west. They also provide considerable habitat for other species as a result of their high relief. Finally, C Shoal and D Shoal are additional candidates for inclusion in an MPA network. It had extensive Acropora ]]>
framework with small stands of living A. palmata in shallow (2-5m depth) areas and extensive diverse deeper coral habitats composed of large Montastraea-dominated communities, patches of Acropora cervicornis and the only large stands of Madracis mirabilis and Porites porites seen in the region.
Acknowledgments
The data presented ]]>
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Received 04-IX-2013 Corrected 02-I-2014 Accepted 24-III-2014