Sellers Joseph C, Holstein Daniel M, Botha Tarryn L, Sikkel Paul C
Center for Marine and Environmental Studies, University of the Virgin Islands, St. Thomas, VI, 00802, USA.
Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, 1002-Y Energy, Coast and Environment Building, Baton Rouge, LA, 70803, USA.
Oecologia. 2019 Feb;189(2):293-305. doi: 10.1007/s00442-018-4262-8. Epub 2018 Oct 22.
The transition from a planktonic larval stage to a benthic or demersal juvenile stage, "recruitment", is a crucial event in the life history of coral reef fishes, and has a strong influence on population size. Predation by piscivorous fishes is thought to be the main determinant of recruitment success, and has received the most attention. However, recent studies suggest that recently settled reef fishes are also an important target of micropredation from blood-feeding ectoparasites which may have significant lethal and sublethal effects. In this study, we quantified the relationship between levels of infestation by gnathiid isopods and mortality rates among juveniles of three species of reef fishes as a function of body mass both within and among species. We found that a single gnathiid isopod larva could kill fish of all three species shortly after settlement, up to 0.116 g [18 mm fork length (FL)] in French grunt (Haemulon flavolineatum), 0.027 g (15 mm FL) in masked goby (Coryphopterus personatus) and 0.01 g (9 mm FL) in beaugregory damselfish (Stegastes leucostictus). For juvenile S. leucostictus, we also compared the ability of fish to defend a territory when infested with a sublethal number of gnathiids versus uninfected individuals. Uninfected fish were significantly more likely to win-pairwise contests versus infected fish. These findings suggest that gnathiids can significantly impact juvenile coral reef fish survival, and affect population dynamics well past the settlement stage.
从浮游幼虫阶段过渡到底栖或近岸幼鱼阶段，即“补充”，是珊瑚礁鱼类生活史中的一个关键事件，对种群规模有很大影响。食鱼性鱼类的捕食被认为是补充成功的主要决定因素，并且受到了最多的关注。然而，最近的研究表明，刚定居的礁鱼也是吸血外寄生微捕食的重要目标，这可能会产生重大的致死和亚致死影响。在本研究中，我们量化了三种礁鱼幼鱼身上寄生的食骨虫等足类动物的感染水平与死亡率之间的关系，该关系是物种内部和物种之间体重的函数。我们发现，一只食骨虫等足类幼虫在定居后不久就能杀死所有这三种鱼类，对于法国鲷（黄斑九棘鲈），能杀死体重达0.116克[叉长（FL）18毫米]的个体；对于蒙面虾虎鱼，能杀死体重0.027克（FL 15毫米）的个体；对于黄尾蓝魔雀鲷，能杀死体重0.01克（FL 9毫米）的个体。对于黄尾蓝魔雀鲷幼鱼，我们还比较了感染亚致死数量食骨虫的鱼和未感染个体在保卫领地方面的能力。未感染的鱼在成对竞争中战胜感染鱼的可能性显著更高。这些发现表明，食骨虫会对珊瑚礁幼鱼的生存产生重大影响，并在定居阶段之后很长时间影响种群动态。
