Determinants of parasite species richness in Mediterranean marine fishes

Abstract

Data on parasites of Mediterranean Sea fishes, collected from previous published surveys, were used to test 5 hypotheses concerning the determinants of parasite species richness. A total of 170 parasite species belonging to 5 distinct taxonomic groups (nematodes, acanthocephalans, digeneans, monogeneans and crustaceans) were identified from 79 marine fish species (3904 individuals) collected at a regional scale. Five independent variables concerning host life traits (body size, diet, range, abundance and schooling) were investigated and controlled for host sampling effort. A comparative analysis uslng the independent contrasts method was conducted In order to avoid phylogenetic confounding effects. We demonstrate the importance of taking host sampling effort into account when Investigating the determinants of parasite species richness. Monogeneans were the only group for which the species nchness showed a significant correlation with some of the variables studied. Parasite specles richness of monogeneans was posltlvely correlated with host body size and negatively correlated with host species abundance. The pos~tive relationship between fish body size and the number of parasite specles on a regional scale may b e explained by the hypothesis that larger host body size increases host vagility which in turn enhances exposure to more and more parasite species. Our findings disagree with previous studies that did not take either phylogenetic confounding effects or geographic scale into account. We demonstrate the importance of using phylogenetic information in comparative analyses by showing that fish body size was not correlated with geographical range when using phylogenetic independent contrasts. We also suggest that studying parasites of host species from the same geographical region avolds the problem of confounding various assemblages of hosts w~t h distinct histories.

Prevalence, intensity and abundance of endoparasites in Oreochromis niloticus and Tilapia zilli (Pisces: Cichlidae) from Asa Dam, Ilorin, Nigeria

“…There has been contrasting results obtained between parasite burden and size of fish (length and weight). Other previous studies reported relationship between length and weight (Price & Clancy, 1983), while in others there was no relationship (Sasal, Morand & Guegan, 1997).…”

Effectiveness of European Atlanto-Mediterranean MPAs: Do they accomplish the expected effects on populations, communities and ecosystems?

“…observ.). The increase in density and size of fishes inside marine reserves can also facilitate the spread of certain types of directly transmitted parasitic diseases (Sasal, 2003;Sasal et al, 1996;Sasal et al, 1997).…”

Species Richness of Parasite Assemblages: Evolution and Patterns

“…Other host characteristics have also been implicated as determinants of the richness of parasite faunas because of their potential influence on colonization or extinction rates. These include host density, diet, behavior, and various life-history traits (5,33,71,85,88). Also, because parasites are more likely to colonize a new host species related to their current host (81), the phyletic diversity of a host taxon may help to shape its parasite fauna.…”