St. Eustatius GCRMN Caribbean Final Report 2019
Twenty-two sites across four monitoring zones of St. Eustatius’ marine ecosystem within the national marine park were assessed using the Global Coral Reef Monitoring Network Caribbean Initiative (GCRMN-Caribbean) guidelines between August and October 2019. The protocol extracted data that indicated the biomass of key fish species and overall reef health including but not limited to relative abundance of macroalgae and hard coral, coral disease prevalence, coral recruit density and rugosity to name a few. Using the Reef Health Index (McField and Kramer 2007), St. Eustatius’ coral reef ecosystem is in “Fair” condition (RHI Score = 3). Coral cover remains below 5% with a statistically insignificant increase from the previous year’s estimate (2015 = 5.19%, 2016 = 4.99%, 2017 = 4.73%, 2018 = 4.21% and 2019 = 4.57 %) with macroalgae continuing to dominate (2015 = 27.93%, 2016 = 27.92%, 2017 = 25.33%, 2018 = 23.89% and 2019 = 32.45%). Combined algal benthic cover (fleshy macroalgae, cyanobacteria and turf algae) was 80%, further securing algal dominance on Statia’s reefs. Overall increase in fish biomass and density hints at the success of the marine reserves and the spillover effect. Biomass of parrotfish, surgeonfish, groupers and snappers have been “very good” over the last 3 years. Populations of these key species are greater when compared to other Eastern Caribbean territories. Large-bodied groupers and snappers were not observed during our surveys within the St. Eustatius Marine Park except for one yellowmouth grouper observed at the Cave on the Atlantic Side. Porites astreoides, remains the dominant species on Statia’s reefs due to its successful reproductive strategy as a hermaphroditic brooder with it accounting for 34% of the species composition of observed recruits. Key reef building genera such as Orbicella spp, Montastrea and Pseudodiploria spp which have a benthic cover range between 0 – 15.57% only accounted for 0-1.2 % per species of recruits observed. This implies that the future of corals on Statia’s reefs is gravely uncertain as the abundance of new reef building recruits are too low. Stony Coral Tissue Loss Disease was the most prevalent disease observed on Statia’s reefs having been first observed in August 2019. Mitigative and restorative measures are desperately needed. Emphasis is again placed on the need to focus on diversifying coral restoration techniques that target reef building genera such as Orbicella and Psuedodiploria along with the repopulation of Diadema antillarum. D. antillarum densities recorded during this survey effort where < 1 individual/100m2.