When people think of the effects of cities on wildlife, changes on land often first come to mind. But, urban areas also have major impacts on aquatic life, especially near sewage treatment plants. These sewage plants dump billions of liters of effluent per day into estuaries and oceans, and this waste can contain a veritable cocktail of pathogens, heavy metals, and pharmaceuticals that may harm marine organisms. In addition, nutrients from this effluent indirectly lead to low pH in coastal waters. This acidification is particularly stressful to molluscs (e.g. clams, oysters, mussels), since it interferes with their ability to properly form shells as they grow.
Dr. Jonathan Puritz (University of Rhode Island) and colleagues are interested in the evolutionary response of eastern oysters to sewage effluent, especially the combined effects of acidification and sewage. They exposed oyster larvae in the lab to one of three treatments: low pH, sewage effluent, or a combination of low pH and sewage, plus a control group not exposed to either stressor. They then measured survival and larval growth. Oysters exposed to low pH had similar survival rates to the control group, but mortality was much higher in the sewage treatment group. When the sewage and acidification treatments were combined, mortality tended to be even higher than in the treatments with only one stressor.
Ongoing and future work in this system aims to identify alleles that are correlated with survival in these stressful situations. Overall, this study highlights some of the many ways urban areas can impact nearby aquatic animals. It also shows the importance of understanding the combined effects of multiple stressors. For more information, check out the Puritz lab website or follow them on Twitter.
Google Scholar Profile
- Migrating Monarchs in Manhattan - October 8, 2019
- Urban Evolution at Behaviour 2019 - July 18, 2019
- Evolution 2019: Adaptation to Coastal Stressors in Oyster Larvae - June 24, 2019
Leave a Reply