External Abnormalities and Body Deformities of Noble Crayfish (Malacostraca, Astacidae: <i>Astacus astacus</i>) of West Carpathian Massive (Slovakia): Possible Causes for this Phenomenon

Abstract Astacus astacus (Linnaeus, 1758) is a vulnerable species. Through comprehensive monitoring, we have determined the current spatial distribution of populations in two streams Western Carpathian Massif. In investigated part streams, did not detect presence source chemical contamination with hazardous substances causing aquatic animal mortality or significant deterioration environmental quality. We sampled at 30 study sites and examined 223 individuals, more than third which showed abnormalities, physical damage, body deformation, ectosymbionts. External abnormalities were related to carapace abdomen; both sexes, most frequent on claws (amputation, stunting, mechanical damage); males, frequently observed amputation antennae, commissural damage; females, also found very low egg counts stunted deformities pleopods, telson deformities. On bodies crayfish, confirmed ectosymbionts from genus Branchiobdella as well.