Study: Oxygen Loss in Coos Bay

By Caley Eller

Climate change is a problem that the entire world faces, but it may impact Oregon sooner rather than later.

According to a University of Oregon study by UO assistant professor Dave Sutherland and based on research done by UO alumnus Molly A. O’Neill, the coastal city of Coos Bay, Oregon, could soon face drastic climate change-related changes to the ocean’s oxygen levels. The interesting part of the study, however, is that Coos Bay has long had oxygen levels that are higher than any other coastal region in the state.

Research for the study began when Sutherland was interested in the measurements of O’Neill’s monthly water samples for her master’s thesis, including salinity, temperature, acidity and levels of dissolved oxygen. When he looked through 50 years’ worth of documents, he discovered that physical aspects of Coos Bay’s estuary flush out old water in the summer season when other parts of Oregon’s coast struggle with hypoxia, a lack of oxygen in the biotic environment. According to the study, freshwater from the Coos River helps to move older, less-oxygenated water out, and fresher water with more oxygen takes its place; moving winds also help to move the water along.

In other coastal areas, winds over the offshore shelf eventually create a stagnant environment, leading phytoplankton populations to increase near the surface. After these populations increase, they die off and sink to the bottom, which creates an oxygen-depleted zone that affects salmon, crabs, oysters, clams, and other bottom-dwelling organisms and cool-water fish.

This factor will only worsen as climate change progresses, according to Sutherland and multiple studies and reports.

Even though Coos Bay’s oceanic waters seem to be safe for now, the study is a tool for officials to monitor the waters and to predict how climate change may have an impact on the threat of hypoxia.