Coastal Hypoxia

The occurrence of low dissolved oxygen (i.e. hypoxia) in coastal waters is a global environmental problem (see figure below from Diaz & Rosenberg, 2008). Although hypoxia may be a natural feature of many aquatic systems, there is also an unequivocal link to anthropogenic nutrient inputs and organic matter loading. Climate change has also been identified as a factor contributing to the frequency and intensity of hypoxia in coastal and estuarine waters.

Hypoxia in Bellingham Bay

Recently, attention on hypoxia has shifted to the Pacific Northwest, where large areas of hypoxic waters (<4 mg O2 L-1) have been identified in Hood Canal and off the coast of central Oregon. Hypoxic waters have also been identified in smaller Puget Sound embayments such as Bellingham Bay. Prompted by reports from native Lummi fishermen of black, smelly mud in central Bellingham Bay, students at Northwest Indian College enrolled in the Native Environmental Science Program launched an investigation into potential causes. These monitoring efforts have grown into a collaborative effort between NWIC and researchers at Western Washington University's Shannon Point Marine Center. Results from this study have revealed a large area of seasonally hypoxia water in central Bellingham Bay. This phenomenon has also been observed by WWU researcher Dr. Bert Webber and is corroborated by analysis of monitoring data from Washington Department of Ecology.

Despite this growing body of research, basic ecological and mechanistic understanding of hypoxia in Bellingham Bay is lacking. Without this information, it is difficult to develop effective management strategies that address the problem of hypoxia in Bellingham Bay and how it might respond to long-term changes in watershed hydrology, population growth, and climate.

Bellingham Bay (left) is a coastal embayment in northern Puget Sound. Hypoxic waters typically cover a substantial portion of the central Bay and appear to be related to an area of highest residence time. Although the temporal and spatial extent of this hypoxia has not been quantified, preliminary data suggest it may last for up to 2-3 months during the summer.

 

 

Click here to view a presentation on the Bellingham Bay Hypoxia Study given at the Pacific Estuarine Research Society meeting held in Bellingham during March 2009.

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