Effects of hypoxia on the seasonal cycle of zooplankton communities in Puget Sound, WA

Hypoxia is increasing in severity with global climate change and is predicted to lead to changes in zooplankton diversity and species composition. In particular, hypoxia is hypothesized to lead to increased dominance of taxa with low metabolic rates such as gelatinous species and cyclopoid copepods, and a decrease in the larger crustaceans that are preferred prey of many upper trophic level organisms. We are studying relationships between ocean chemistry and zooplankton in Puget Sound, Washington—a deep, seasonally hypoxic fjord in the Pacific Northwest that supports a diverse zooplankton community. How zooplankton species composition, behavior, growth, and energy flow to predators are altered by hypoxia is a focus of our research. Here we will examine the hypothesis that seasonal hypoxia leads to changes in zooplankton community structure using in situ sampling from late spring to early fall at four sites along a gradient of oxygen conditions in two contrasting years. We use multi-species analysis techniques to quantify changes in the zooplankton to better understand community-level responses to hypoxia and potential implications to fish