Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology, Melbourne, Florida, United States of America.
Biodiversity and Reef Conservation Laboratory, Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, México.
PLoS One. 2024 Oct 11;19(10):e0311344. doi: 10.1371/journal.pone.0311344. eCollection 2024.
The composition of coral-reef sediments is highly variable across space and time, and differences in the life histories of the dominant calcifying organisms on reefs contribute to the heterogeneity of reef sediments. Previous studies have suggested that variations in coral-reef bioerosion can influence spatial and temporal variations of sedimentary assemblages: elevated erosion rates of dead coral skeletons can trigger a pulse of coral-derived sediments and cause a shift in the dominance of sedimentary grains from coralline algae, such as Halimeda, to coral. We assessed the variability of the sedimentary composition and bioerosion rates of reefs at different spatial scales to determine the association between these two variables. We surveyed the benthic assemblages on reefs exhibiting different ecological states and collected samples of the associated sediments. We calculated the carbonate budget for each site and compared their variability at different hierarchical levels to the variability of their respective sedimentary assemblages. At the scale of sites (1-10 km), Halimeda cover was a significant predictor of the relative abundance of Halimeda grains. Both the relative abundance of coral grains and reef bioerosion rates varied significantly at the scale of locality (tens to hundreds of km), with high abundances of coral grains in the sediments coinciding with high rates of bioerosion. The main drivers of bioerosion at our localities were parrotfish assemblages dominated by large size classes of excavating species such as Sparisoma viride. Reef sediments may reflect the gross degree of bioerosion pressure that reefs experience, and historical changes in bioerosion rates could potentially be assessed by examining the sediments across temporal scales.
珊瑚礁沉积物的组成在空间和时间上高度可变，而礁上优势钙化生物的生活史差异导致了礁沉积物的异质性。先前的研究表明，珊瑚礁生物侵蚀的变化会影响沉积物组合的空间和时间变化：死珊瑚骨骼的侵蚀率升高会引发珊瑚衍生沉积物的脉冲，并导致沉积颗粒的优势从珊瑚藻（如 Halimeda）转变为珊瑚。我们评估了不同空间尺度上的珊瑚礁沉积物组成和生物侵蚀率的可变性，以确定这两个变量之间的关系。我们调查了具有不同生态状态的珊瑚礁上的底栖生物组合，并收集了相关沉积物的样本。我们计算了每个地点的碳酸盐预算，并将其在不同层次上的可变性与各自沉积物组合的可变性进行了比较。在地点尺度（1-10 公里）上，Halimeda 覆盖率是 Halimeda 颗粒相对丰度的重要预测因子。珊瑚颗粒的相对丰度和礁生物侵蚀率在局部尺度（数十到数百公里）上都有显著变化，沉积物中珊瑚颗粒的高丰度与生物侵蚀率的高值相对应。在我们的局部地区，生物侵蚀的主要驱动因素是由大型挖掘物种（如 Sparisoma viride）主导的鹦鹉鱼组合。珊瑚礁沉积物可能反映了珊瑚礁所经历的生物侵蚀压力的总体程度，通过在时间尺度上检查沉积物，可能可以评估生物侵蚀率的历史变化。
