Parasites of fish Poecilia velifera and their potential as bioindicators of wetland restoration progress

Abstract

Fish harbor a high diversity of parasites that play an important role for the ecosystem. Because these parasites have different life-cycle traits, changes in their populations or communities may provide useful information related to ecosystem health. Highly stressful conditions may reduce parasite communities or populations. However, it is not a rule since host-parasite interactions are hardly predictable. In this study, macroparasites of the fish sailfin molly (Poecilia velifera) from three sites (conserved, degraded and under restoration) located within a mangrove wetland area, in the Terminos Lagoon (southern Gulf of Mexico), were analyzed in order to determine their potential use as bioindicators. A total of 198 fish were examined for parasites. Six parasite species were found: two crustaceans (Argulus sp. and Ergasilus aff. cerastes), one trematode (Centrocestus formosanus), one monogenean (Gyrodactylus sp.) and two nematodes (Contracaecum sp. and Cuculanus sp.). There were no significant differences in the structure of parasite infracommunities as well as in prevalence and intensity of parasite populations between degraded and conserved sites. However, the site under restoration had poorer infracommunities and smaller populations of crustaceans and trematodes, which suggests that restoration efforts have not improved the ecological conditions. Based on these results, it is conjectured that parasites of P. velifera did not show useful information to provide a diagnosis related to ecosystem health. Beyond this ecological subject, the present study represents new host record for most parasite species found.