Spatiotemporal Variation in Coral Assemblages and Reef Habitat Complexity among Shallow Fore-Reef Sites in the Florida Keys National Marine Sanctuary

Abstract

With the unprecedented degradation and loss of coral reefs at multiple scales, the underlying changes in abiotic and biotic features relevant to the three-dimensional architecture of coral reefs are critical to conservation and restoration. This study characterized the spatiotemporal variation of habitat metrics at eight fore-reef sites representing three management zones in the Florida Keys, USA using visual habitat surveys (2017–2018) acquired before and after Hurricane Irma. Post-hurricane, five of those sites were surveyed using structure-from-motion photogrammetry to further investigate coral morphology on structural complexity. Multivariate results for visual surveys identified moderate separation among sites, with fished sites characterized by complex physical features such as depth and vertical hard relief while protected sites generally harbored high abundances of live coral cover. Three-dimensional models of mapped sites showed within site variation as another driver in site separation. Additionally, fine-scale orthoimage analyses identified significant differences in dominant coral morphologies at each mapped site. This study suggests protected reef sites generally harbor higher live coral cover despite some fished sites being structurally similar in seabed topography. Our work provides fine-scale spatial data on several managed sites within a marine sanctuary and highlights the contribution of diverse coral assemblages to the coral reef framework.

Dead but not forgotten: complexity of Acropora palmata colonies increases with greater composition of dead coral

“…Consequently, if future assessments exclude dead coral, they may fail to capture additional components of reef complexity and the ecological mechanisms they support. Further linking 3D structures with ecological assessments can inform conservation management to enhance biodiversity and reef resilience ( Simmons, DelWayne & Eggleston, 2022 ; Helder, Burns & Green, 2022 ; Curtis et al, 2023 ). The ecological insights gained from concurrently assessing biotic, abiotic, and 3D reef characteristics will likely increase over time as changing climatic conditions, local disturbances, and anthropogenic stressors continue to create a myriad of reef conditions ( Anthony et al, 2008 ; Hughes et al, 2017 ; Claar et al, 2020 ).…”