LC-HRMS Tracks Pollutant Effects in Bay Mussels

Animals living in coastal waters can be harmed by man-made pollutants that find their way into the ocean. This study used advanced biological analysis techniques to examine how exposure to stormwater runoff, wastewater, and other real-world environmental conditions affects the health of bay mussels. To do this, researchers at the University of Washington Tacoma extracted hemolymph from the mussels' circulatory systems (which is like blood in humans) and performed analysis of metabolite abundance using liquid chromatography-high resolution mass spectrometry (LC-HRMS) instrumentation. A paper based on this work was published in Marine Pollution Bulletin.¹

Why is Puget Sound a Concern for Environmental Pollution?

With more than five million people living in the surrounding area, Puget Sound is under significant pressure from human activity, receiving a steady flow of pollutants through stormwater runoff and wastewater discharge.² While researchers have identified a wide range of contaminants in these waters, much less is known about the actual harm these pollutants cause to the animals living there.³ Several programs in the region are working to track both the presence of these contaminants and their effects on local wildlife. One of these is the Mussel Watch program, run by the National Oceanic and Atmospheric Administration (NOAA) and managed locally by the Washington Department of Fish and Wildlife. This ongoing monitoring program places native bay mussels (serving as an important indicator species, as their health reflects environmental conditions, particularly in the nearshore⁴) at sites throughout Puget Sound to track how pollutants build up in their bodies over time, providing a window into the overall health of coastal wildlife in the region.⁵

How Does Exposure to Stormwater and Wastewater Affect the Health of Bay Mussels?

One of the advantages of analyzing metabolites in the host’s body is that changes in their levels can signal that an organism has been exposed to harmful substances long before any visible signs of illness appear. In this study, mussels were brought into a laboratory setting and exposed to varying concentrations of stormwater runoff and wastewater. At the same time, mussels from the same source were placed at selected locations throughout Puget Sound, Washington (areas known to be affected by stormwater and wastewater discharge) to see how real-world environmental conditions would affect them.¹

Analysis of the hemolymph extracted from the mussels revealed clear signs that contaminant exposure was affecting their body chemistry. Mussels exposed to even a very dilute stormwater solution showed changes in five biological markers. Wastewater exposure had an even greater impact; at a very low concentration, three markers were affected, but as the concentration increased tenfold, that number jumped to 34 altered markers. Among the mussels placed in Puget Sound, 28 biological markers were affected across the various locations, with one site in particular showing changes that closely resembled those seen in mussels exposed to wastewater in the laboratory.¹

“Results from the wastewater exposure,” write the authors of the paper,¹ “indicate alterations in bioenergetic pathways associated with key outcomes, including growth and reproductive success.”

The researchers believe that more analysis is necessary to better understand how long-term exposure to these contaminants affects energy levels in the body, and whether the body adapts over time. Additionally, studies spanning multiple generations could help build on these findings by exploring how changes in these biological markers connect to real-world impacts on reproductive health and fertility.¹

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References

1. Clemens, J.; Faber, M.; Mathews, H. M. et al. Metabolomic Alterations in Marine Mussels Exposed to Wastewater, Stormwater, and Environmental Conditions. Mar Pollut Bull. 2026, 231, 119936. DOI: 10.1016/j.marpolbul.2026.119936
2. Research in Puget Sound: Carbon Cycling and Ocean Acidification Along an Urban Land-Ocean Interface.PMEL Carbon Program. NOAA website 2025. https://www.pmel.noaa.gov/co2/story/Research+in+Puget+Sound
3. Tian, Z.; Peter, K. T.; Gipe, A. D. et al. Suspect and Nontarget Screening for Contaminants of Emerging Concern in an Urban Estuary. Environ. Sci. Technol.2020, 54 (2), 889-901. DOI: 10.1021/acs.est.9b06126
4. Holt, E. A.; Miller, S. W. Bioindicators: Using Organisms to Measure Environmental Impacts. Nat. Educ. Knowl.2010, 3 (10), 8.
5. Mussel Watch. Washington Department of Fish and Wildlife (WDFW) website 2025. https://wdfw.wa.gov/species-habitats/science/marine-toxics/monitoring/mussel-watch