Gut of goatfishes, a heterogeneous biotope for intestinal mesoparasites : structure and growth models of colonizable digestive surface area
Résumé
Fish organs constitute biotopes for various parasites. In the case of gills or digestive tracts, hosts of different ages and sizes lead to a heterogeneity in these biotopes at the fish population level. The digestive tracts of goatfishes Mullus surmuletus and M. barbatus harbour several species of helminths that colonize the pyloric caeca and intestine. The structural heterogeneity of this biotope is analysed by study of variations in caeca number and colonizable surface area. Caeca number varies between host species and among individuals of the same population. Colonizable intestinal surface area also varies between goatfish species and increases with fish size, but differently according to the intestinal parts considered. These variations were studied, using image-processing techniques, and analysed quantitatively. Theoretical growth models are proposed and some consequences for parasite ecology discussed.