Cymothoid fish parasites settle on hosts in ways that may impact fish health and energetics. High abundances of Artystone minima observed in Nannostomus beckfordi from the Jeju River in eastern Amazonia were investigated to answer the following questions: (a) What factors are associated with the high prevalence at this locality?; (b) Is high abundance associated with co‐infestation of alternative hosts?; and (c) Is parasite presence associated with host species growth and/or reproduction? Fish assemblages were sampled quarterly (August 2017–May 2018) from five habitats along with environmental data. Parasitic indices were calculated, and parasite presence used to evaluate differences in growth of hosts using analysis of covariance considering host sex and sampling season (wet vs. dry). Parasites were only abundant in one of the habitats, a large, shallow backwater bay with macrophytes. Abiotic environmental factors (flow and depth) likely impact parasite transmission and are, therefore, particularly important in producing these local patterns. Two secondary hosts, Hyphessobrycon cf. rosaceus and Moenkhausia collettii, were found in the wet season. Based on host biology compared to other fish in the habitat, parasite infestation is inferred to be depth associated and long‐term infestation is apparently limited in alternative hosts. Parasite presence was significantly associated with reduced weight (standardized for length) of female Nannostomus beckfordi in the wet season. Furthermore, ovaries of non‐parasitized females from the wet season presented a range of maturation stages, while parasitized females were all immature, indicating a significant association of parasites with host reproductive capacity.

中文翻译：

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亚马逊东部东部鱼类觅食性寄生物Artystone minima（Cymothoidae：Isopoda）的栖息地和寄主协会

拟食肉类鱼类寄生虫以可能影响鱼类健康和能量的方式在寄主上定居。在南诺斯托克·贝克福德（Nannostomus beckfordi）中观察到高丰度的小结石对来自亚马逊东部的济州河的居民进行了调查，以回答以下问题：（a）该地区的高流行与哪些因素有关？（b）大量感染与替代宿主的共同感染有关吗？（c）寄生虫的存在与宿主物种的生长和/或繁殖有关吗？每季度（2017年8月至2018年5月）从五个栖息地取样鱼群以及环境数据。计算寄生指数，并使用考虑宿主性别和采样季节（湿与干）的协方差分析，使用寄生虫的存在来评估宿主生长的差异。寄生虫仅在其中一种生境中丰富，该生境是一个大型浅水回水湾，上面有大型植物。非生物环境因素（流量和深度）可能会影响寄生虫传播，因此，在产生这些局部图案时特别重要。两个辅助主机，Hyphessobrycon比照。在雨季发现了酒渣鼻和红叶锦葵。根据宿主生物与生境中其他鱼类的比较，推断寄生虫侵染与深度有关，而替代宿主中长期侵染显然受到限制。雨季中，寄生虫的存在与雌性Nannostomus beckfordi的体重减轻（以身长标准化）显着相关。此外，雨季中未寄生虫的雌性卵巢呈现一系列成熟阶段，而被寄生虫的雌性均未成熟，表明寄生虫与宿主繁殖能力显着相关。