Coal toxcitiy to mussels

Toxicity tests were conducted at the U.S. Geological Survey Columbia Environmental Research Center (CERC), Columbia, Missouri to determine the effects of sediments from impacted (historic coal mining or gas well activities) and un-impacted (these activities did not occur) river sites on growth and mortality of 2 mo old rainbow mussels (Villosa iris). Tissue from surviving juveniles from one replicate (n = 1) of each of the sediment exposures were histologically processed and qualitatively evaluated to determine sub-lethal effects on their organ and visceral tissues. Many tissues were improperly embedded, but re-embedding allowed most tissues to be blindly evaluated. Microscopical inspections of diverticula of digestive glands revealed no abnormalities. Where elaborated in sections, kidneys, ganglia, posterior adductor muscles, heart/rectum complexes, and vesicular connective tissues showed no evidence of pathologies. Results of the evaluations of gill tissues showed a general dichotomy among juveniles exposed to sediments from un-impacted and impacted sites. Most gill filaments in sections from mussels exposed to un-impacted sediments contained abundances of frontal, latero-frontal, and lateral cilia and epithelial tissues. Evaluations of gill filament tissues of mussels exposed to sediments from impacted sites revealed abnormalities, including absence or reduction in abundances of cilia, deterioration of epithelial layers and hemocoalic spaces, fusion of filaments, and reductions of cytoplasm in ciliated cells. During the evaluations, unidentified organisms were observed in digestive tracts of some juveniles from control, un-impacted, and impacted sediment exposures. The organism was not observed in any other organ tissues. In some sections, presumptive pedicels that connected the organism to mussel tissues were observed. Further study of infected juveniles will determine whether these organisms affect health of infected juvenile mussels.