Monitoring metal stress in Puget Sound using metallothionein production in mussels in the nearshore

Toxic metals are common contaminants in sediments near industrial ports and in stormwater from urban areas throughout the Salish Sea. Although pollutant concentrations have been mapped in the sediments, waters and biota of Puget Sound for decades, equating these contaminant levels to biological impacts has been attempted infrequently. Moreover, many of these attempts at studying metal toxicity have not been applied to the ecologically and economically important nearshore area. As part of the Washington Department of Fish and Wildlife’s (WDFW) 2012-2013 MusselWatch Pilot Expansion Project, an effort to develop a nearshore biomonitoring protocol for Puget Sound, mussels of the same age and reared in the same location were transplanted to over 100 locations throughout Puget Sound in November 2012. Mussels were secured in quadruplicate batches in nylon netting suspended in 16x16x16 inch cages and anchored in the low intertidal by volunteers. The mussels were allowed to equilibrate with their surroundings for two months and retrieved in January 2013. All mussels were measured and weighed by WDFW staff and supervised volunteers, shucked and homogenized, and then frozen to await analysis. A portion of each homogenized sample was delivered to the University of Washington Tacoma for analysis of metallothioneins, cysteine-rich proteins used in the metal detoxification mechanism of mussels and other bivalves. Metallothioneins were derivatized with monobromobimane, separated by reverse phase high-pressure liquid chromatography, and analyzed with a fluorescence detector. Our results and correlations with parameters measured by other WDFW collaborators, including metal concentrations and growth characteristics, will be presented. With limited funding available for toxics remediation it is imperative to develop monitoring tools that measure biological impacts specific to metal stress, and to apply those tools to understanding ecological health in the nearshore