Fifteen miles off the coast of Belize sits Carrie Bow Cay, a sandy island that could comfortably fit onto a football field, with a history of marine field research nearly 50 years and counting. Carrie Bow is home to Smithsonian’s Caribbean Coral Reef Ecosystems (CCRE) program and hosts over 100 visiting scientists a year, lured by proximity to coral reef, mangrove, and seagrass habitats. Among those visitors are Smithsonian MarineGEO scientists, who have maintained a 5-year time series of rigorous biodiversity monitoring in the habitats surrounding the island.
Since 2014, MarineGEO teams have led expeditions to Carrie Bow each autumn to test new research approaches and track change in the reef and associated ecosystems. We focus on the five key habitat types surrounding the island: forereef, patch reef, mangrove, seagrass, and bare sand. Across this network of tropical habitats, we’ve been investigating research questions such as:
- How does diversity and composition of the biological community and the functions it accomplishes vary with habitat?
- How does abundance of foundation species such as corals and seagrasses vary across the study area?
- Are community structure, ecosystem function, and benthic cover changing over time?
A key approach we use to tackle these questions uses diver visual surveys of fishes and large invertebrates, in partnership with Reef Life Survey, to investigate animal community structure. To understand how the fishes are affecting the ecosystem, we use baited assays of predation (squidpops) and grazing (weedpops) to, and photoquadrats to quantify changes in cover of corals and other benthic life. We also survey seagrass shoot density and morphology, associated invertebrates, coral species demographics, coral health, and calcium accretion. In 2019, we partnered with Drs. Tim Hawthorne and Bo Yang of the University of Central Florida to collect aerial imagery via drone of the island and surrounding areas and to ground-truth the resultant habitat maps, laying the groundwork for an aerial monitoring component of our long-term research.
While our data collection in 2020 and 2021 were delayed by the Coronavirus pandemic, the MarineGEO team capitalized on time away from the field to analyze our Carrie Bow datasets. In the process, we’ve found that stony coral cover on our shallow forereef sites has doubled over our study period (de Pablo et al. 2021), and that consumption of squidpops and weedpops is consistently higher on forereefs and patch reefs than in other habitats, with a few key fish species primarily responsible (Ritter et al. 2021). We’ve also analyzed patterns in fish beta diversity across the five habitats surveyed, and found that bare sand habitats have surprising and often unrecognized contributions to tropical fish biodiversity. The MarineGEO team is eagerly awaiting a post-pandemic return to Carrie Bow, planned for 2022.