Habitat/sex differences in time at cleaning stations and ectoparasite loads in a Caribbean reef fish

We compared time spent at cleaning stations and ectoparasite loads for adul t and subadult yellowtail damselfish Microspathodon chrysurus on nearshore fringing reefs in Barbados. In a preliminary study on 2 reefs in summer 199 7, both time spent at cleaning stations and frequency of chafing were inver sely correlated with distance from shore. A subsequent study in spring 1998 of fish at the shore- and seaward ends of 8 reefs revealed a strong sex by habitat association, with males predominating at the seaward end and femal es predominating at the shore end. Females and combined fish at the shore e nd of reefs had access to fewer cleaners but spent more time visiting clean ers than males and combined fish at the seaward end of reefs. Chafing showe d the same relative difference but was not significant. Ectoparasites inclu ded gnathiid isopod larvae, parasitic copepods, and dactylogyrid monogenean s. Total crustacean loads, but not monogenean loads, increased with body si ze. With the effects of body size statistically removed, crustacean loads w ere significantly higher in females and fish at the shore end of reefs. Mon ogeneans showed a similar but marginally non-significant trend. These data indicate an association between ectoparasite loads and amount of time spent at cleaners, and thus appear consistent with adaptive, mutualistic hypothe ses of client-cleaner interactions. However, the causal relationships betwe en them, habitat, and sex remain to be determined.