Crayfish diet and mercury bioaccumulation in AMD impacted streams

Mercury contamination is a major concern in aquatic ecosystems. This study investigated the relationship between crayfish dietary content and mercury bioaccumulation in crayfish tail tissue as well as the relationship between acid mine impact and crayfish trophic level in southeast Ohio’s Sunday Creek watershed. Crayfish were sampled from 20 sites (10 acid mine impacted and 10 non-impacted sites).  Gut content analyses determined crayfish trophic level and crayfish tail tissue mercury content was measured using GC- ICP-MS. Mercury concentrations in crayfish tail muscle tissue (except at one stream site RH01) fell below published EPA threshold concentrations for fish tissue. Stomach content analysis yielded an assortment of  plant matter (remains of vascular plants, green algal like material, bark like material, autochthonous and allochthonous woody debris and detritus in various stages of digestion), animal matter ( macro invertebrate mandibles, fragments of arthropod appendages, fragments of fish scales, crayfish cuticle) and amorphous matter ( gel like, dark brown liquid). Gastroliths were found in the crayfish at some sites. The observed lack of correlations (between crayfish diet and mercury body burden as well as between acid mine impact and trophic level) coupled with subsequent power analyses suggest that our sample sizes may have been insufficient