No abstract

No abstract

We compared time spent at cleaning stations and ectoparasite loads for adult and subadult yellowtail damselfish Microspathodon chrysurus on nearshore fringing reefs in Barbados. In a preliminary study on 2 reefs in summer 1997, both time spent at cleaning stations and frequency of chafing were inversely 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 females predominating at the shore end. Females and combined fish at the shore end of reefs had access to fewer cleaners but spent more time visiting cleaners than males and combined fish at the seaward end of reefs. Chafing showed the same relatlve difference but was not significant. Ectoparasites included gnathiid isopod larvae, parasitic copepods, and dactylogyrid monogeneans. Total crustacean loads, but not monogenean loads, increased with body size. With the effects of body size statistically removed, crustacean loads were significantly higher in females and fish at the shore end of reefs. Monogeneans 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 hypotheses of client-cleaner interactions. However, the causal relationships between them, habitat, and sex remain to be determined.

No abstract

No abstract

No abstract

Susceptibility to infestation by a gnathiid isopod (Gnathia marleyi: Crustacea: Isopoda) was examined among 16 species from 9 families and 3 orders of common Caribbean reef fishes off St. John, United States Virgin Islands. Fish were placed in cages during times of peak gnathiid activity. Individuals from most (n=14) species were compared against a single species (French Grunt, Haemulon flavolineatum) that served as a standard and effectively controlled for the effects of habitat and variation in gnathiid abundance on exposure to and the likelihood and intensity of host infestation by gnathiids. All species were susceptible to infestation by gnathiids, with individual hosts harbouring up to 368 gnathiids. However, there was significant variation in levels of infestation among the 14 comparison species. Controlling for body size, nocturnal species from the families Haemulidae and Lutjanidae had the highest gnathiid infestation. Our finding that haemulids and lutjanids are particularly susceptible has important implications for the role of gnathiids in Caribbean reef food webs, given the role members of these families play in trophic connectivity between reefs and associated habitats. To our knowledge this is the first manipulative field study to examine variation among potential hosts in susceptibility to an ectoparasite in any terrestrial or aquatic system and is the greatest number of teleost hosts documented for any gnathiid species.

Escape from parasites in their native range is one of many mechanisms that can contribute to the success of an invasive species. Gnathiid isopods are blood-feeding ectoparasites that infest a wide range of fish hosts, mostly in coral reef habitats. They are ecologically similar to terrestrial ticks, with the ability to transmit blood-borne parasites and cause damage or even death to heavily infected hosts. Therefore, being highly resistant or highly susceptible to gnathiids can have significant fitness consequences for reef-associated fishes. Indo-Pacific red lionfish (Pterois volitans) have invaded coastal habitats of the western tropical and subtropical Atlantic and Caribbean regions. We assessed the susceptibility of red lionfish to parasitic gnathiid isopods in both their native Pacific and introduced Atlantic ranges via experimental field studies during which lionfish and other, ecologically-similar reef fishes were caged and exposed to gnathiid infestation on shallow coral reefs. Lionfish in both ranges had very few gnathiids when compared with other species, suggesting that lionfish are not highly susceptible to infestation by generalist ectoparasitic gnathiids. While this pattern implies that release from gnathiid infestation is unlikely to contribute to the success of lionfish as invaders, it does suggest that in environments with high gnathiid densities, lionfish may have an advantage over species that are more susceptible to gnathiids. Also, because lionfish are not completely resistant to gnathiids, our results suggest that lionfish could possibly have transported blood parasites between their native Pacific and invaded Atlantic ranges.