Emergent Contaminants and Effects on Field-Exposed Chinook Salmon and Cutthroat Trout in the Stillaguamish Watershed, WA.

Contaminants of emerging concern (CECs) are chemical compounds that have no regulatory standards, are recently discovered in the natural environment due to improved analytical methods, and can potentially cause adverse effects to aquatic life. More specifically, CECs affecting fish communities include endocrine disrupting chemicals (EDCs), which can produce developmental abnormalities or alter the epigenome, potentially affecting survival and reproductive success. This study assessed CEC occurrence as well as toxicological and epigenetic responses of caged, hatchery-reared Chinook salmon (Oncorhynchus tshawytscha) and field-collected, wild, resident cutthroat trout (O. clarkii) at sites representing different land uses in the Stillaguamish River watershed, Washington State. This study was comprised of two experiments over two years: the first hatchery-reared juvenile Chinook salmon were caged for 28-days and the second, wild, resident cutthroat trout were captured via electroshocking. This study analyzed presence and concentrations of CEC analytes in stream water using Polar Organic Chemical Integrative Sampler (POCIS) devices across all study sites. The study analyzed chemical contaminants in fish tissues (i.e., liver and gall bladder), as well as vitellogenin (VTG) protein in blood plasma. Gene expression was analyzed using microarray technology. Contaminants of emerging concern occurrences and concentrations were generally low, although somewhat higher at sites receiving urban or agricultural runoff or wastewater treatment effluent. Chemical analyses indicated low CEC concentrations in sampled tissue from both Chinook and cutthroat, as most analytes were not detected above reporting limits. Vitellogenin protein results revealed few measurable detections. Analysis of gene expression also suggest overall weak responses relative to controls. Overall, this study found some CEC pollution, mostly at sites influenced by urbanization, agriculture or wastewater effluent, but there was little to no indication that CECs are affecting fish health in the Stillaguamish watershed.