Elevated feeding rates of fishes within octocoral canopies on Caribbean reefs
Elevated feeding rates of fishes within octocoral canopies on Caribbean reefs
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DOI：
10.1007/s00338-020-01963-1
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发表时间：
2020-06
期刊：
影响因子：
3.5
通讯作者：
G. Tsounis;M. Steele;P. Edmunds
中科院分区：
文献类型：
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作者：
G. Tsounis;M. Steele;P. Edmunds
加勒比海珊瑚礁上越来越多的树栖珊瑚（通常称为柳珊瑚）提出了一个问题，即珊瑚提供的生境结构是否可以通过增加鱼类丰度和草食性来调解珊瑚和藻类占主导地位的国家之间的过渡。本研究测试的假设，摄食率和密度的底栖礁鱼类的栖息地结构所提供的密集的珊瑚礁群落的影响。对美属维尔京群岛圣约翰珊瑚礁上的鱼类进行的调查发现，在密集的珊瑚冠层内，鱼类的密度是珊瑚冠层外的1.7倍，摄食率是珊瑚冠层外的2.4倍。然而，这种差异仅在珊瑚密度> 8个菌落m-2的地点观察到。此外，珊瑚群落与鱼类的接近程度对主要食草动物（外科鱼类和鹦嘴鱼）的摄食率有影响，在珊瑚群落附近（< 20或30厘米，取决于地点）的摄食率（1.90 ± 0.11次叮咬/min− 1 m −2）比远离它们（1.24 ± 0.09次叮咬/min− 1 m −2）高53%。最后，在密集的珊瑚群落（17个菌落m-2）的树冠内，珊瑚鱼的摄食率是群落内的2.2倍，高于群落边缘的2.2倍。然而，鱼类丰度并不是均匀地高于在边缘的珊瑚群落，作为生态交错区的专家，如虎鱼，blennioids，介形虫，holocentrids，labrids和pomacentrids的1.3-2.3倍更丰富的边缘。相比之下，其他类群的底栖鱼类，特别是草食动物，丰富的珊瑚群落内的两倍，比在边缘。总之，这些结果揭示了栖息地结构之间的关联创建的浅礁和底栖鱼类（包括那些食草动物）的摄食率增加的珊瑚礁。因此，珊瑚虫增加食草动物的潜力，可能介导石珊瑚的恢复，值得进一步研究。
Increasing abundance of arborescent octocorals (often referred to as gorgonians) on Caribbean reefs raises the question of whether habitat structure provided by octocorals can mediate a transition between coral- and algal- dominated states by increasing fish abundance and herbivory. This study tested the hypotheses that feeding rates and densities of demersal reef fishes are affected by the habitat structure provided by dense octocoral communities. Surveys of fishes on coral reefs in St John, US Virgin Islands, found 1.7-fold higher densities, and 2.4-fold higher feeding rates within versus outside of dense octocoral canopies. This difference, however, was only seen at sites with octocoral densities > 8 colonies m−2. Furthemore, the proximity of octocoral colonies to fish had an effect on the grazing rate of key herbivores (surgeonfishes and parrotfishes), with a 53% higher feeding rate (1.90 ± 0.11 bites min−1m−2) near octocorals (< 20 or 30 cm, depending on the site) versus farther from them (1.24 ± 0.09 bites min−1m−2). Finally, within the canopy of dense octocoral communities (17 colonies m−2), reef fishes fed at a rate that was 2.2-fold higher within the community than at the edge of the community that faced an adjacent sand patch. Fish abundance, however, was not uniformly higher within versus at the edge of the octocoral community, as ecotone specialists such as gobiids, blennioids, ostraciids, holocentrids, labrids, and pomacentrids were 1.3—2.3 times more abundant at the edge. In contrast, other taxa of demersal fishes, notably herbivores, were twice as abundant within octocoral communities than at the edges. Together, these results reveal an association between habitat structure created by octocorals on shallow reefs and increased feeding rates of demersal fishes (including those of herbivores). The potential of octocorals to increase herbivory that could mediate stony coral recovery is therefore worthy of further study.