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 in the long term from repeated ectoparasite removal remain relatively unknown. Here, we tested whether long-term reduced access to cleaning services alters 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) have been 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.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: A.F.H.R., A.S.G., R.B.; Methodology: A.F.H.R., A.S.G., R.B.; Validation: A.F.H.R.; Formal analysis: A.F.H.R., D.N., Z.T., R.B.; Investigation: A.F.H.R., D.N., R.B.; Resources: R.B.; Data curation: A.F.H.R., D.N.; Writing - original draft: A.F.H.R.; Writing - review & editing: A.F.H.R., D.N., Z.T., A.S.G., R.B.; Visualization: A.F.H.R., D.N., Z.T.; Supervision: R.B.; Project administration: A.S.G., R.B.; Funding acquisition: A.S.G., R.B.
Funding
This study was supported by the Australian Research Council (DP120102415 to A.S.G. and R.B.), the Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (31003AB_135707 and 31003A_153067 to R.B.), and the Swiss Government excellence scholarship (2012.2014 to Z.T.).
Data availability
The detailed script generated in R for the current analysis along with the associated data are available from the figshare digital repository: https://figshare.com/s/e9c75c69e88980a46d85.
Supplementary information
Supplementary information available online at https://jeb.biologists.org/lookup/doi/10.1242/jeb.231613.supplemental
- Received June 22, 2020.
- Accepted November 9, 2020.
- © 2020. Published by The Company of Biologists Ltd
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