The ultimate effect of being cleaned: does ectoparasite removal have reproductive consequences for damselfish clients?

The mutualistic nature of cleaning symbioses has long remained unconfirmed because of the difficulty in showing net benefits for clients. We have previously shown that cleaning gobies (Elacatinus spp.) within territories of Caribbean longfin damselfish (Stegastes diencaeus) reduce the number of gnathiid isopod ectoparasites on territory owners. We now investigate whether this benefit of being cleaned has reproductive consequences for male longfin damselfish. The mating success, rate of egg loss, and parental aggression of 40 nest-guarding males were assessed during six consecutive monthly reproductive periods. Ten males had cleaning stations within their territory, 10 males were without cleaning stations, and 20 males initially with a cleaning station had their cleaners removed half-way through the study. Ectoparasite loads on our focal fish were very low; however, damselfish with cleaning stations still had significantly fewer ectoparasites than did fish without cleaning stations. There was, however, no significant difference in the number of eggs, clutches, or area of clutches received, or in the number of eggs lost before hatching between damselfish with and without cleaners. We also found no difference in parental male aggression between damselfish with and without cleaners. We conclude that although ectoparasite removal appears to have no direct consequence for reproduction, at least for the levels of infestations observed on our study site, it may still affect other aspects of damselfish fitness such as survival. Copyright 2003.