Recent paper shows unarmored sites in Puget Sound taxa-rich


A recent publication in Estuaries and Coasts investigates the impacts of shoreline armoring along the Duwamish River estuary in Central Puget Sound on salmon diets, invertebrate communities and environmental conditions.

Habitat transformation

Approximately 1/3 of Puget Sound’s nearly 4,000 km of shoreline is armored: that is, the natural shoreline habitat has been replaced by bulkheads, sea walls, rip-rap, etc., designed to protect against erosion owing to wave action. Because of the importance of habitat interfaces for the function of many different types of ecosystems, researchers in Puget Sound are focused on how this habitat transformation is affecting the Puget Sound ecosystem, including intertidal species, food webs and water quality. Sarah Morley at NOAA’s Northwest Fisheries Science Center (NWFSC), along with colleagues from the NWFSC and the University of Washington, in a recent publication in Estuaries and Coasts have investigated the impacts of shoreline armoring along the Duwamish River estuary in Central Puget Sound on salmon diets, invertebrate communities and environmental conditions.

Greater species richness and density

Morley and colleagues found that at unarmored sites, epibenthic invertebrate communities were twice as taxa-rich and 10 times as dense (number of individuals per unit area) than at armored sites. In addition, the community of invertebrates found on the water’s surface, the neuston, was also more taxa-rich at unarmored sites. The diets of chum salmon were different between armored and unarmored sites, while Chinook salmon diets were not. This work by local researchers reflects the types of questions being asked about how shoreline alterations affect Puget Sound food webs and ecosystem function, and provides important information to help managers evaluate the trade-offs associated with different actions.


Morley SA, JD Toft and KM Hanson. 2012. Estuaries and Coasts 35(3): 774-784.

Open Access:

By Tessa Francis

Tessa joined the PSI in 2012. She is an aquatic ecologist, and her research is related to aquatic food webs, and the impacts of climate and other environmental variables on food-web dynamics. She is interested in the important associations between terrestrial and aquatic habitats, and how watershed and shoreline dynamics impact aquatic food webs and populations. At the PSI, Tessa is engaged in projects related to food webs in Puget Sound, forage fish, the risk of shoreline armoring to Puget Sound species and food webs, and the movement of contaminants through pelagic food webs.

As a postdoctoral researcher at NOAA's Northwest Fisheries Science Center, Tessa conducted food-web analyses of the Northern California Current ecosystem. This included describing the effects of large-scale climate indices and local environmental conditions on zooplankton community interaction networks. Tessa, with colleagues at NOAA and NCEAS/UC Santa Barbara, developed a moving-window autoregressive model to describe changes in zooplankton community stability through time, and to identify correlations between stability and the Pacific Decadal Oscillation (PDO). She also used a qualitative food-web model to identify the key prey and predators of groundfish species of importance in the Northern California Current. Tessa also reviewed the use of futures analyses in the Puget Sound region, and this work contributed to the Puget Sound Science Update (

Tessa’s PhD dissertation focused on the consequences of lakeshore urbanization in the Pacific Northwest on lake food webs, shallow-water habitats, macroinvertebrate communities and ecosystem processes including land-water interactions. She conducted research related to the importance of marine-derived nutrients delivered by sockeye salmon to streams in southwestern Alaska. She also reviewed the use of Best Available Science in updates of Washington State's Critical Areas Act by local jurisdictions.

Tessa also holds a B.A. in Political Science, and has worked in theater, film and television.