Many “client” coral reef fishes have their ectoparasites removed by the “cleaner” wrasse Labroides dimidiatus in mutualistic interactions . Clients regularly receiving cleaning services reportedly benefit from increased growth and cognitive performance, but the underlying physiological changes that covary with such benefits are unknown. Here, we tested whether reduced access to cleaning services affects physiological state in two species of damselfish, Amblyglyphidodon curacao and Acanthochromis polyacanthus. We performed an in situ removal experiment on the Great Barrier Reef, Australia, whereby 47% of cleaners on a natural reef were removed. Since cleaners occupy defined territories (called “cleaning stations”), this removal created areas where small, resident clients, including A. polyacanthus and A. amblyglyphidodon , had no access to cleaning services. One month following cleaner removal, we measured body condition and collected blood samples from both damselfish species from territories with and without access to cleaners. Blood was used for estimating haematocrit levels, hormonal analyses, and immune cell counts. We tested for correlations among all these parameters to explore potential trade-offs in terms of growth, aerobic capacity, immune activation, and/or reproduction as a result of the loss of cleaning benefits. In both species, we found that fish without access to cleaners had lower haematocrit, testosterone levels, and lymphocyte counts than fish with access. There were no significant changes in fish body condition, leukocytes, granulocytes, or plasma cortisol levels between fish with access to cleaners or not. However, testosterone levels correlated negatively with the proportion of granulocytes in the blood of fish with access to cleaners. Our results suggest that even a relatively short-term reduction in access to cleaning services can have negative physiological outcomes for clients. Thus, the presence of cleaners on coral reefs appears to have important benefits for coral reef fish community health.

中文翻译：

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减少获得清洁鱼的机会对两种常驻珊瑚鱼的生理状态产生负面影响

许多“客户”珊瑚礁鱼类的体外寄生虫被“更清洁的”濑鱼 Labroides dimidiatus 在互惠互利中清除。据报道，定期接受清洁服务的客户受益于增长和认知能力的提高，但与这些好处相关的潜在生理变化尚不清楚。在这里，我们测试了减少清洁服务是否会影响两种雀鲷（Amblyglyphidodon curacao 和 Acanthochromis polyacanthus）的生理状态。我们在澳大利亚大堡礁进行了原位清除实验，从而清除了天然礁石上 47% 的清洁剂。由于清洁工占据了特定的区域（称为“清洁站”），这种移除创造了一些小型常驻客户，包括 A. polyacanthus 和 A. Amblyglyphidodon，无法获得清洁服务。去除清洁剂后一个月，我们测量了身体状况，并从有和没有清洁剂的地区收集了两种雀鲷的血液样本。血液用于估计血细胞比容水平、激素分析和免疫细胞计数。我们测试了所有这些参数之间的相关性，以探索由于失去清洁益处而导致的生长、有氧能力、免疫激活和/或繁殖方面的潜在权衡。在这两个物种中，我们发现没有清洁剂的鱼的血细胞比容、睾酮水平和淋巴细胞计数低于有清洁剂的鱼。无论是否使用清洁剂，鱼的身体状况、白细胞、粒细胞或血浆皮质醇水平都没有显着变化。然而，睾酮水平与能够使用清洁剂的鱼血液中的粒细胞比例呈负相关。我们的结果表明，即使是相对短期地减少获得清洁服务的机会，也会对客户产生负面的生理影响。因此，珊瑚礁上清洁剂的存在似乎对珊瑚礁鱼类群落的健康有重要的好处。