Department of Biological Science, Florida State University, Tallahassee, United States of America.
Coastal and Marine Laboratory, Florida State University, St. Teresa, FL, United States of America.
PeerJ. 2023 Oct 11;11:e16101. doi: 10.7717/peerj.16101. eCollection 2023.
Coral reefs are highly biodiverse ecosystems that have declined due to natural and anthropogenic stressors. Researchers often attribute reef ecological processes to corals' complex structure, but effective conservation requires disentangling the contributions of coral versus reef structures. Many studies assessing the relationships between reef structure and ecological dynamics commonly use live coral as a proxy for reef complexity, disregarding the contribution of dead coral skeletons to reef habitat provision or other biogeochemical reef dynamics. This study aimed to assess the contribution of dead coral to reef complexity by examining structural variations in live and dead colonies. We used photogrammetry to reconstruct digital elevation models (DEMs) and orthomosaics of the benthic region immediately surrounding 10 colonies. These reconstructions were used to quantify structural metrics, including surface rugosity, fractal dimension, slope, planform curvature, and profile curvature, as a function of benthic composition (, live , dead , or non- substrate). The results revealed that dead coral maintained more varied profile curvatures and higher fractal dimensions than live or non-coral substrate. Conversely, colonies with a higher proportion of live coral displayed more uniform structure, with lower fractal dimensions and less variability in profile curvature measures. Other metrics showed no significant difference among substrate types. These findings provide novel insights into the structural differences between live and dead coral, and an alternative perspective on the mechanisms driving the observed structural complexity on reefs. Overall, our results highlight the overlooked potential contributions of dead coral to reef habitat provision, ecological processes, and other biogeochemical reef dynamics, and could have important implications for coral reef conservation.
珊瑚礁是高度多样化的生态系统，由于自然和人为压力而减少。研究人员通常将珊瑚礁生态过程归因于珊瑚的复杂结构，但有效的保护需要理清珊瑚与珊瑚礁结构的贡献。许多评估珊瑚礁结构与生态动态之间关系的研究通常将活珊瑚作为珊瑚礁复杂性的替代物，而忽略了死珊瑚骨架对珊瑚礁栖息地供应或其他生物地球化学珊瑚礁动态的贡献。本研究旨在通过检查活珊瑚和死珊瑚的结构变化来评估死珊瑚对珊瑚礁复杂性的贡献。我们使用摄影测量法来重建 10 个珊瑚礁周围的近床区的数字高程模型（DEM）和正射镶嵌图。这些重建用于量化结构指标，包括表面粗糙度、分形维数、坡度、平面曲率和剖面曲率，作为底质组成（活、死或非基质）的函数。结果表明，死珊瑚保持了更多样化的剖面曲率和更高的分形维数，而活珊瑚或非珊瑚基质则不然。相反，活珊瑚比例较高的 珊瑚礁具有更均匀的结构，分形维数较低，剖面曲率的变化较小。其他指标在基质类型之间没有显著差异。这些发现为活珊瑚和死珊瑚之间的结构差异提供了新的见解，并为驱动珊瑚礁观察到的结构复杂性的机制提供了另一种视角。总的来说，我们的研究结果强调了死珊瑚对珊瑚礁栖息地供应、生态过程和其他生物地球化学珊瑚礁动态的被忽视的潜在贡献，并可能对珊瑚礁保护具有重要意义。
