Fluctuating asymmetry of sclerotized structures of Haliotrematoides spp. (Monogenea: Dactylogyridae) as bioindicators of aquatic contamination

[Display omitted] •Fluctuating asymmetry (FA) of anchor form in Haliotrematoides spp. was assessed.•Evidence of shape and size FA of ventral anchors of H. striatohamus was found.•FA was statistically associated with contaminants and environmental variables.•Experimental evidence of contamination affecting FA in monogeneans is needed. Fluctuating asymmetry (FA) and increased variation in bilateral symmetry in a sample of monogeneans can indicate disturbance in developmental stability caused by environmental and/or genomic stress. This study was conducted to determine the presence of FA in the sclerotized structures of Haliotrematoides spp. (Monogenea) collected along the continental shelf of the Yucatán Peninsula. We hypothesize the potential effect of chemical contamination on FA. Geometric morphometrics with Procrustes ANOVA was used to test FA in the ventral and dorsal anchors in Haliotrematoides spp. Then, Generalized Additive Model for Location, Scale and Shape (GAMLSS) were used to assess the statistical associations of heavy metal concentrations, Polycyclic Aromatic Hydrocarbons (PAHs), gene expression, PAHs metabolites in bile, fish morphometric measurements, physicochemical and spatial variables on FA patterns. Principal Component Analysis showed no clear group formation according to shape variability by sampling site. Evidence of FA for size and shape in ventral anchors of Haliotrematoides striatohamus was found, in contrast to dorsal anchors, which only displayed shape FA. For Haliotrematoides sp. only evidence for shape FA of ventral and dorsal anchors was found. The GAMLSS models revealed a significant positive relationship between the FA of Haliotrematoides spp. and PAHs, Pb, Naphthalene, Ni, pH, Hydroxy-Phenanthrene, Depth, DNA Methylation, Glutathione peroxydase and Condition factor (K). These results partially support our hypothesis that FA in the anchors would be produced by aquatic contamination but in association to other environmental variables and host related factors.