Center for Ecology and Environment, Tunghai University, Taichung, Taiwan.
Department of Life Science, Tunghai University, Taichung, Taiwan.
PLoS One. 2019 Jun 14;14(6):e0218413. doi: 10.1371/journal.pone.0218413. eCollection 2019.
Little is known about long-term changes in coral reef fish communities. Here we present a new technique that leverages fish otoliths in reef sediments to reconstruct coral reef fish communities. We found over 5,400 otoliths in 169 modern and mid-Holocene bulk samples from Caribbean Panama and Dominican Republic mid-Holocene and modern reefs, demonstrating otoliths are abundant in reef sediments. With a specially-built reference collection, we were able to assign over 4,400 otoliths to one of 56 taxa (35 families) though mostly at genus and family level. Many otoliths were from juvenile fishes for which identification is challenging. Richness (by rarefaction) of otolith assemblages was slightly higher in modern than mid-Holocene reefs, but further analyses are required to elucidate the underlying causes. We compared the living fish communities, sampled using icthyocide, with the sediment otolith assemblages on four reefs finding the otolith assemblages faithfully capture the general composition of the living fish communities. Radiocarbon dating performed directly on the otoliths suggests that relatively little mixing of sediment layers particularly on actively accreting branching coral reefs. All otolith assemblages were strongly dominated by small, fast-turnover fish taxa and juvenile individuals, and our exploration on taxonomy, functional ecology and taphonomy lead us to the conclusion that intense predation is likely the most important process for otolith accumulation in reef sediments. We conclude that otolith assemblages in modern and fossil reef sediments can provide a powerful tool to explore ecological changes in reef fish communities over time and space.
关于珊瑚礁鱼类群落的长期变化，人们知之甚少。在这里，我们提出了一种新的技术，利用珊瑚礁沉积物中的鱼类耳石来重建珊瑚礁鱼类群落。我们在来自加勒比巴拿马和多米尼加共和国中全新世和现代珊瑚礁的 169 个现代和中全新世的批量样本中发现了超过 5400 个耳石，证明耳石在珊瑚礁沉积物中很丰富。通过专门建立的参考收藏，我们能够将超过 4400 个耳石分配到 56 个分类群（35 个科）中的一个，尽管大多数是在属和科的水平上。许多耳石来自于难以识别的幼年鱼类。通过稀疏化，现代珊瑚礁中的耳石组合的丰富度略高于中全新世珊瑚礁，但需要进一步分析才能阐明潜在原因。我们将使用鱼毒剂采集的活体鱼类群落与四个珊瑚礁的沉积物耳石组合进行了比较，发现耳石组合忠实地捕捉了活体鱼类群落的一般组成。直接在耳石上进行的放射性碳测年表明，特别是在活跃的分枝珊瑚礁上，沉积物层的混合相对较少。所有的耳石组合都强烈地由小而快速周转的鱼类分类群和幼年个体主导，我们对分类学、功能生态学和埋藏学的探索使我们得出结论，强烈的捕食可能是耳石在珊瑚礁沉积物中积累的最重要过程。我们的结论是，现代和化石珊瑚礁沉积物中的耳石组合可以为探索珊瑚礁鱼类群落随时间和空间的生态变化提供有力的工具。
