Metabolomic alterations in marine mussels exposed to wastewater, stormwater, and environmental conditions.

Organisms in nearshore environments can be affected by anthropogenic contaminants, potentially leading to poor outcomes. This study applies metabolomic methods to evaluate the influence of stormwater, wastewater, and field exposures on the biological responses of bay mussels (Mytilus trossulus). Metabolomics provides a sensitive measure of interactions between an organism and its environment and can show indications of contaminant exposure well before other symptoms appear. Mussels were exposed under laboratory conditions to multiple dilutions of stormwater or wastewater. Additionally, mussels from the same source were deployed to select field sites throughout Puget Sound, Washington that were expected to be influenced by stormwater and/or wastewater. Hemolymph was extracted, and samples were analyzed for metabolite abundance using Liquid Chromatography-High Resolution Mass Spectrometry instrumentation. Analysis showed exposure-related metabolic alterations, with 0.5% stormwater exposure resulting in 5 significantly altered metabolites. Wastewater exposure resulted in a greater number of significant alterations and provided insight into the impacts of different contaminant doses. Exposure to a 0.1% wastewater solution resulted in 3 significantly altered metabolites, a number that increased to 34 significantly altered metabolites in the 1% wastewater exposure group. Field deployment resulted in 28 significantly altered metabolites across locations, with one site showing significant metabolic alteration consistent with wastewater exposure when compared to the reference site. Results from the wastewater exposure indicate alterations in bioenergetic pathways associated with key outcomes, including growth and reproductive success.