The impact of long-term reduced access to cleaner fish on health indicators of resident client fish

Abstract

In many mutualisms, benefits in the form of food are exchanged for services such as transport or protection. In the marine cleaning mutualism, a variety of “client” reef fishes offer “cleaner” fish Labroides dimidiatus access to food in the form of their ectoparasites, where parasite removal supposedly protects the clients. Yet, the health benefits individual clients obtain on the long-term from repeated ectoparasite removal remain relatively unknown. Here, we tested whether long-term reduced access to cleaning services alter indicators of health status such as body condition, immunity and the steroids cortisol and testosterone in four client damselfish species Pomacentrus amboinensis, Amblyglyphidodon curacao, Acanthochromis polyacanthus, and Dischistodus perspicillatus. To do so, we took advantage of a long-term experimental project in which several small reefs around Lizard Island (Great Barrier Reef, Australia) were maintained cleaner-free since the year 2000; while control reefs had their cleaner presence continuously monitored. We found that the four damselfish species from reef sites without cleaners for 13 years had lower body condition than fish from reefs with cleaners. However, immunity measurements and cortisol and testosterone levels did not differ between experimental groups. Our findings suggest that clients use the energetic benefits derived from long-term access to cleaning services to selectively increase body condition, rather than altering hormonal or immune system functions.

Relative brain size and cognitive equivalence in fishes

“…We provide an explicit analysis that combines both cognitive performance and brain size as a function of body size in the cleaner fish Labroides dimidiatus (hereafter “cleaner”). Cleaners engage in iterative mutualistic interaction with a variety of coral reef fish (hereafter “client”) to remove their ectoparasites and dead tissue in exchange for food [Losey, 1979], a behaviour that is mutually beneficial for both cleaners [Grutter, 1999] and clients [Demairé et al, 2020; Ros et al, 2020; Clague et al, 2011]. Cleaner fish show a highly sophisticated strategic behaviour that includes reputation management [Bshary, and Grutter, 2002; Binning et al, 2017], social tool use [Bshary et al, 2002], reconciliation [Bshary, and Würth, 2001], and social competence [Triki et al, 2020a].…”

The behavioural ecology of marine cleaning mutualisms

“…For example, Waldie et al (2011) found that two damselfish species were larger on control reefs compared to those from which L. dimidatus had been removed for 8.5 years. After 13 years of cleaner removal, body condition in four species of damselfish was lower on reefs without cleaners compared to those with cleaners (Ros et al, 2020). Thus, over the long term, parasite removal by cleaners may free up energy and resources (e.g.…”

“…Ros et al, 2011) that clients can then channel towards critical processes such as maintaining body condition (e.g. Ros et al, 2020) and growth (e.g. Waldie et al, 2011).…”

Marine Cleaning Mutualism Defies Standard Logic of Supply and Demand

“…Thus, iterated cleaning visits help clients get rid of their current parasites, but it does not prevent reinfections (Grutter et al 2018(Grutter et al , 2019. Clients benefit from accessing cleaning services, like having improved body condition (Clague et al 2011;Waldie et al 2011;Ros et al 2020) and higher hematocrit levels (Demairé et al 2020). The study by Demairé et al…”