Ecological effects of intertidal geoduck culture
Sea Grant National Strategic Investment funds enabled university researchers to use traditional food-habit measuring techniques, chemical analyses, and energetic models to examine the effects of geoduck aquaculture operations on trophic relationships in Puget Sound.
Glenn VanBlaricom, University of Washington, School of Aquatic and Fishery Sciences
David Beauchamp, University of Washington, School of Aquatic and Fishery Sciences
Brett Dumbauld, USDA, Agriculture Research Service
With funding from a National Strategic Initiative, researchers investigated the effects of the intertidal culture of Pacific geoduck clams on community dynamics and trophic interactions. Building on the results of previous Washington State-funded research, investigators identified key prey for fish and crab associated with geoduck farm sites. Working with the industry and shoreline property owners, they conducted studies of the site fidelity, growth, and stable isotope signatures of Pacific staghorn sculpin, a ubiquitous local predator and useful indicator of ecosystem changes, and they modeled the energetics of sculpin and their prey.
The expansion of geoduck aquaculture in Puget Sound has raised concern among resource managers, conservation organizations, and the public regarding its environmental impacts. Aquaculture structures may affect a number of ecological functions and processes, including predator and prey distribution.
A mark–recapture study found that staghorn sculpin show fidelity to their initial capture sites. Analysis of diet samples and comparison to previous data demonstrated that sculpin consume different types of prey in different habitats. But despite some minor differences in prey-chemistry composition, the sculpin evinced similar carbon and nitrogen stable isotope ratios at farm and reference areas across the summer months, indicating that their trophic position and general food-web function were unchanged. These findings have important implications for geoduck aquaculture management and will inform regulatory decisions related to it.
Armintrout K (2011) A bioenergetics model for Staghorn sculpin at sites in south Puget Sound. Undergraduate Capstone thesis, University of Washington.