Variation in Food Web Connectivity across Intertidal Gradients in Embayment and Fluvially- Dominated Estuaries

University Of Washington, Seattle WA

Investigators

Abstract

Detritus-based food webs fueled by dead organic matter from terrestrial, estuarine and coastal ecosystems support many consumer organisms (e.g., zooplankton, crabs, clams, fish) in the coastal zone. But whether these food webs are uniformly available (i.e., highly connected) to estuarine consumers or occur discretely (compartmentalized in space and time) is not entirely clear. Although recent studies have shown that the spatial scale, strength and persistence of food web links to specific detritus sources can rapidly change over narrow transition zones, these studies were located in microtidal estuaries with little or no adjacent riverine input. This study will evaluate food web compartmentalization among five estuaries in northern Puget Sound to quantify the scale, strength and mechanisms (water flow) of food web connections along intertidal gradients of estuarine marsh, mudflat, and seagrass ecosystems under differing freshwater influences. The scale of our experiments will range from meters to kilometers and from seasonal to interannual. Quantifying scales, strengths and persistence of food web connectivity to different living and detrital sources will help refine ecosystem-based approaches to managing estuarine and coastal restoration, protection, and resource use. Results will shed light on how estuarine restoration actions such as removing levees to reintroduce tidal processes, or establishing estuarine reserves, may expand the scale of food web connectivity beyond location of the management action. By examining a variety of Pacific Northwest estuaries influenced by rivers, this study will also address the effect of river flow and watershed alteration on ecosystem connectivity across different coastal settings.