Slimy, smelly, and superfun(d): Investigating water quality, invertebrate communities, and pyrethroid insecticides in the Duwamish River ecosystem

Background/Question/Methods   Water and sediment quality were compared across seven restoration sites by measuring biotic and abiotic components of the Duwamish River waterway in Seattle, WA. The river is an industrial waterway, international port, and EPA Superfund site, and is home to a variety of invertebrates that play a significant role in the ecosystem. Our research strives to better understand the relationships within this community that has undergone restoration efforts for the past ten years. Standard water quality measures of DO, pH, photic depth, turbidity, salinity, and plankton abundance were collected from all sites over a five month period. We expected areas of more restoration to have higher water quality, intermediate nutrient levels, and greater invertebrate abundance and size.

Results/Conclusions   Results show progress in some measures at restoration sites, as DO concentrations were highest at sites with more restoration progress. Other patterns included higher nutrient levels near outfalls with nitrogen and phosphorus levels peaking near CSOs and creek mouths, respectively. Sizes of invertebrates (isopods, amphipods, and polychaetes) and pH increased downstream. These results are an initial assessment of differences in aquatic characteristics among the sites and suggest the need for further work to better elucidate relationships among abiotic and biotic components and how they are affected by restoration. Despite restoration progress, the Duwamish River is still heavily polluted with a variety of toxins including pyrethroid insecticides. We are now examining the non-lethal effects of pyrethroids on isopods, including feeding rates, growth rates, and the ability to respond to predators. Predator chemical cues and stress cues are used to determine how the presence of those toxins affects the invertebrates' abilities to respond to stress in their environment.