The metazoan parasite communities of flounders as indicators of chemical pollution in the southern Gulf of Mexico: taxonomic and trait-based approaches

Abstract

Metazoan parasite species composition changes with an increase in geographical distance, but not their functional traits. We compared the performance of the taxonomy and functional traits of metazoan parasites as bioindicators of chemical pollution along the continental shelf of the South Gulf of Mexico (sGOM). Parasites were obtained from Syacium gunteri and Syacium papillosum, together with hydrocarbons, heavy metals and physicochemical variables from water and sediments during 12 oceanographic cruises. We compared regions without oil extraction: Veracruz-Tamaulipas (VT) and Yucatan shelf (YS) and one with it, north-western end of YS to Coatzacoalcos, Veracruz (NYV). In addition to taxonomy, the trait-based approach community-weighted means (CWM) was performed. Species richness was compared between regions using rarefaction curves, and the taxonomic and trait composition between regions were compared using multivariate analyses. The relationships between taxonomy, traits and environmental variables were tested using BIOENV. We identified 57 species and body tegument, transmission, feeding mode, life stage and attachment organs as informative traits. By rarefaction, VT and YS had higher species richness than NYV for both hosts, but there were questionable values due to the small fish sample size. Except for YS, significant parasite community variability was detected by PERMANOVA using taxonomy and CWM for all regions, hosts and interactions. The same group of larval species was detected by SIMPER for regions and hosts, suggesting low functional turnover. BIOENV showed that polyaromatic hydrocarbons explained most of the variability. Taxonomy and functional traits produced similar explained variance, but the latter saved time analysis and financial resources.