Sam Irwin, San Diego State University

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Abstract:

Solomon’s Harbor, MD, a shallow water estuary connected to the Chesapeake Bay, is suffering from a lack of dissolved oxygen. The two primary drivers of this oxygen depletion are the introduction of excess nutrients and climate change, which are known to increase temperatures and decrease dissolved oxygen (DO) levels. To better understand the factors that influence DO, we performed a univariate analysis of a 36-year-long historical dataset, deployed temperature sensors at seven sites for a month, and conducted dark box incubations on water samples collected on-site. Temperature was determined to be the strongest factor that explains DO, especially in bottom waters. Hydrodynamics were also impactful on DO and temperature because they determine water mixing, residence times, and variability at individual sites. Temperature was also strongly impacted by distance to the mouth of Solomon’s Harbor, with sites further away having higher temperatures than sites close to the mouth. The sites furthest from open water have less mixing, higher residence times, more variability, are more heavily impacted by sunlight and weather, and have higher average temperatures, so these sites contain the most vulnerable habitat and should be closely monitored and made a conservation priority.