Structure of the parasite communities of a coral reef fish assemblage (Labridae): testing ecological and phylogenetic host factors

The role of ecological and phylogenetic processes is fundamental to understanding how parasite communities are structured. However, for coral reef fishes, such information is almost nonexistent. In this study, we analyzed the structure of the parasite communities based on composition, richness, abundance, and biovolume of ecto- and endoparasites of 14 wrasse species (Labridae) from Lizard Island, Great Barrier Reef, Australia. We determine whether the structure of the parasite communities from these fishes was related to ecological characteristics (body size, abundance, swimming ability, and diet) and/or the phylogenetic relatedness of the hosts. We examined 264 fishes from which almost 37,000 individual parasites and 98 parasite categories (types and species) were recorded. Gnathiid and cestode larvae were the most prevalent and abundant parasites in most fishes. Mean richness, abundance, and biovolume of ectoparasites per fish species were positively correlated with host body size only after controlling for the host phylogeny, whereas no such correlation was found for endoparasites with any host variable. Because most ectoparasites have direct transmission, one possible explanation for this pattern is that increased space (host body size) may increase the colonization and recruitment of ectoparasites. However, endoparasites generally have indirect transmission that can be affected by many other variables, such as number of prey infected and rate of parasite transmission.