Assessment of the Coral Reefs of the Turks and Caicos Islands (Part 1: Stony Corals and Algae)

Major constituents of the benthic reef community (stony corals, algae) were assessed in 28 reefs on the Caicos, Turks and Mouchoir Banks. Living stony coral cover ranged from 8-28%, averaging 18% overall. Montastraea annularis and M. faveolata of “intermediate” sizes (cm) dominated all examined reefs. Acropora palmata and A. cervicornis were scarce. The most frequently recruiting scleractinians were Porites astreoides and Agaricia agaricites; Montastraea recruits were uncommon. Old partial-colony mortality (overall mean = 23%) was greater than recent partial-colony mortality (mean = 3%). Crustose coralline algae and turf algae were generally more abundant than macroalgae. Mouchoir Bank, with the most isolated reefs, was in relatively poor condition, which suggests that remoteness alone does not protect coral reefs

Assessment of the Coral Reefs of the Turks and Caicos Islands (Part 2: Fish Communities)

Ecologically and commercially significant coral reef fishes were surveyed at 28 sites in the Turks and Caicos Islands during August 1999. Our results constitute the first quantitative census of these fishes and can serve as baseline information for subsequent studies. Their density and size generally were highest off West Caicos and lowest in Mouchoir Bank. Herbivore density overall showed no correlation with macroalgal index (a proxy for biomass) or live stony coral cover, but surgeonfish density was positively correlated with macroalgal index. Species richness of these select fishes was positively correlated with the species richness of stony corals that were ≥10cm in diameter. Current fishing pressures overall were low, and the reef-fish communities appeared relatively intact on the Turks and Caicos Banks. However, overfishing and destructive fishing practices have negatively impacted the reef fish communities on Mouchoir Bank

Coping with the Lionfish Invasion: can targeted removals yield beneficial effects?

Invasive species generate significant environmental and economic costs, with maintenance management constituting a major expenditure. Such costs are generated by invasive Indo-Pacific lionfish (Pterois spp.) that further threaten already stressed coral reefs in the western Atlantic Ocean and Caribbean Sea. This brief review documents rapid range expansion and potential impacts of lionfish. In addition, preliminary experimental data from targeted removals contribute to debates about maintenance management. Removals at sites off Little Cayman Island shifted the size frequency distribution of remaining lionfish toward smaller individuals whose stomachs contained less prey and fewer fish. Fewer lionfish and decreased predation on threatened grouper, herbivores and other economically and ecologically important fishes represent key steps toward protecting reefs. However, complete evaluation of success requires long-term data detailing immigration and recruitment by lionfish, compensatory growth and reproduction of lionfish, reduced direct effects on prey assemblages, and reduced indirect effects mediated by competition for food. Preventing introductions is the best way to avoid impacts from invasive species and early detection linked to rapid response ranks second. Nevertheless, results from this case study suggest that targeted removals represent a viable option for shifting direct impacts of invasive lionfish away from highly vulnerable components of ecosystems

Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

BACKGROUND The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.This work was partially supported by salaries from the NOAA Coral Reef Conservation Program to the NOAA Coral Reef Conservation Program authors. NOAA provided funding to Caribbean ReefCheck investigators to undertake surveys of bleaching and mortality. Otherwise, no funding from outside authors' institutions was necessary for the undertaking of this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

A Positive trajectory for corals at Little Cayman Island

Coral reefs are damaged by natural disturbances and local and global anthropogenic stresses. As stresses intensify, so do debates about whether reefs will recover after significant damage. True headway in this debate requires documented temporal trajectories for coral assemblages subjected to various combinations of stresses; therefore, we report relevant changes in coral assemblages at Little Cayman Island. Between 1999 and 2012, spatiotemporal patterns in cover, densities of juveniles and size structure of assemblages were documented inside and outside marine protected areas using transects, quadrats and measurements of maximum diameters. Over five years, bleaching and disease caused live cover to decrease from 26% to 14%, with full recovery seven years later. Juvenile densities varied, reaching a maximum in 2010. Both patterns were consistent within and outside protected areas. In addition, dominant coral species persisted within and outside protected areas although their size frequency distributions varied temporally and spatially. The health of the coral assemblage and the similarity of responses across levels of protection suggested that negligible anthropogenic disturbance at the local scale was a key factor underlying the observed resilience

Coral community decline at a remote Caribbean island: Marine no-take reserves are not enough

1. Coral reefs around the world have been deteriorating over decades owing to anthropogenic pressure. In the Caribbean recent rates of decline are alarming, particularly for coral reefs under high local human impact, many of which are severely degraded, although regions with lower direct anthropogenic influence seem less affected. 2. Little Cayman is a relatively undeveloped island, with less than 150 permanent residents. About 20% of its reefs have been protected by no-take marine reserves since the mid-1980s. We analysed the dynamics of coral communities around the island from 1999 to 2004 in order to test the hypothesis that a lack of major local anthropogenic disturbances is enough to prevent decline of coral populations. 3. Live hard coral coverage, coral diversity, abundance, mortality, size, and prevalence of disease and bleaching were measured using the Atlantic and Gulf Rapid Reef Assessment methodology (line transects) at nine sites. Despite the apparent undisturbed condition of the island, a 40% relative reduction of mean live coral coverage (from 26% to 16%, absolute change was 10%) was recorded in five years. Mean mortality varied from year to year from 23% to 27%. Overall mean diameter and height have decreased between 6% and 15% on average (from 47 to 40 cm for diameter, and from 31 to 29 cm for height). 4. The relative abundance of large reef builders of the genus Montastraea decreased, while that of smaller corals of the genera Agaricia and Porites increased. Disease prevalence has increased over time, and at least one relatively large bleaching event (affecting 10% of the corals) took place in 2003. 5. Mean live coral cover decline was similar inside (from 29% to 19%) and outside (from 24% to 14%) marine no-take reserves. No significant difference in disease prevalence or clear pattern in bleaching frequency was observed between protected and non-protected areas. It is concluded that more comprehensive management strategies are needed in order to effectively protect coral communities from degradation. Copyright © 2007 John Wiley & Sons, Ltd

Gorgonian and Scleractinian Coral Communities of the Turks and Caicos Islands

Shallow-water (4-21 m) coral communities were surveyed at 24 sites spanning over 100km of reef around the Turks and Caicos Islands (TCI) in August 1999. Line transects were used to survey scleractinian and gorgonian communities in the vicinity of Grand Turk, Providenciales, South Caicos, West Caicos and the Mouchoir Bank. A total of 26 scleractinian species among 18 genera and 11 gorgonian genera were recorded in 68 transects. Scleractinian coral species diversity (H’) was 1.77 on average, ranging from 1.04 to 2.29. Comparison among different locations revealed that Providenciales and West Caicos had higher scleractinian diversity than other locations. The number of Gorgonian genera was also highest in West Caicos, but overall scleractinian and gorgonian diversity did not show a correlative relationship. Q-mode cluster analyses of scleractinians, gorgonians, and the whole coral communities all showed the formation of distinct communities separated mainly by locations (islands). However, scleractinians and gorgonians showed a somewhat different way of clustering: gorgonian communities were characterized more strongly by the location, suggesting overall environmental conditions to be an important determinant in gorgonian communities. On the other hand, water depth seemed to play an important role in structuring scleractinian communities. These results implicitly support the hypothesis that different factors are responsible for structuring scleractinians and gorgonians communities

Relationships of invasive lionfish with topographic complexity, groupers, and native prey fishes in Little Cayman

The invasion of Indo-Pacific lionfish on Caribbean reefs has prompted resource-demanding removals. Ecological tools to optimise the outcome of these costly efforts are scarce. Topographic complexity usually correlates strongly with fish abundance and can be mapped over large spatial scales. Determining the nature and strength of its relationship with lionfish abundance is therefore an important step in generating spatial prioritisation tools for removal programmes. Here, we quantify the relationships of lionfish density and hunting behaviour with topographic complexity, grouper biomass, and prey availability on the north-east reefs of Little Cayman. Lionfish density varied across sites irrespective of topographic complexity or density of prey fish, but was highest on the most rugose section of the reef terraces. Increased topographic complexity along the edge of the drop-offs caused modest increases in lionfish density. Grouper biomass caused no clear reduction in mean lionfish density, but narrowed the variance. Lionfish invested more time hunting on rugose sites with a paucity of prey refugia, implying that these may be places where prey fish are most vulnerable to predation. Under the reasonable assumption that lionfish display strong site fidelity, targeted removals are likely to yield the highest conservation benefits if focused on most rugose sites and at the edges of drop-offs. Determining whether longer hunting times yield increased predation rates, and quantifying the effectiveness of physical refugia in protecting prey from lionfish predation strikes, are important future research directions. If topographic complexity determines lionfish hunting success, there is a scope for mapping the vulnerability of prey, thus optimising practises aimed at managing the invasion

Tropical Crustose coralline algal individual and community responses to elevated pCO2 Under high and low irradiance

Crustose coralline algae (CCA) cement reefs and create important habitat and settling sites for reef organisms. The susceptibility of CCA to increasing ocean pCO2 and declining pH or ocean acidification (OA) is a growing concern. Although CCA are autotrophs, there has been little focus on the interaction of elevated pCO2 and irradiance. We examined elevated pCO2 effects on individual CCA and macroalgal benthic communities at high and low irradiance (205-13 μmol photons m-2 s-1) in an aquaria experiment (35 d, June-August 2014) on Little Cayman Island, Caribbean. A dominant Cayman reef wall CCA (Peyssonnelia sp.) in its adult lobed form and individual CCA recruits were used as experimental units. Changes in CCA, fleshy macroalgae (branching and turfs), and microalgae (including microbial biofilm) per cent cover and frequency were examined on macroalgal communities that settled onto plates from the reef. Reef diel cycles of pCO2 and pH were simulated using seawater inflowfrom a back reef. Although CO2 enrichment to year 2100 levels resulted in 1087 μatm pCO2 in the elevated pCO2 treatment, CaCO3 saturation states remained high (Ωcal ≥ 2.7). Under these conditions, elevated pCO2 had no effect on Peyssonnelia sp. calcification rates or survival regardless of irradiance. Individual CCA surface area on the bottom of settling plates was lower under elevated pCO2, but per cent cover or frequency within the community was unchanged. In contrast, there was a strong and consistent community assemblage response to irradiance. Microalgae increased at high irradiance and CCA increased under low irradiance with no significant pCO2 interaction. Based on this short-term experiment, tropical macroalgal communities are unlikely to shift at pCO2 levels predicted for year 2100 under high or low irradiance. Rather, irradiance and other factors that promote microalgae are likely to be strong drivers of tropical benthic algal community structure under climate change