Special Session - Marine and Coastal Applications in Landscape Ecology - Afternoon Session Chair(s): Nicholson, Matt¹, Hinchey, Elizabeth¹, Robbins, Brad², ¹ Atlantic Ecology Branch, Narragansett, RI² Landscape Ecology Program, Sarasota, FL
Friday, April 2, 2004 1:00 PM - 2:40 PM Apollo Room 8

Although applications in landscape ecology traditionally have been restricted to the study of terrestrial systems, the questions defining the science are equally relevant for marine systems. Indeed, knowledge of spatial pattern and the scales at which ecological processes take place is essential for effective management of marine environments. However, scattered and widely disparate field or ship-based observations historically precluded quantification of large-scale marine patterns. Recent advances in remote sensing and other technologies are permitting assessments of pattern and process that never before were possible. It is still unclear how the principles of landscape ecology can be translated into the marine environment, a three-dimensional milieu with physical and biological characteristics that often vary rapidly in space and time. This session will bring together researchers who are attempting to adapt the tools of landscape ecology to address ecological questions within marine and coastal systems. The unique challenges facing the growing field of “seascape” ecology will be addressed.

The influence of non-indigenous smooth cordgrass, Spartina alterniflora, on estuarine ecosystems of the Pacific Northwest. Feist, Blake^*,1, Harvey, Chris¹, Ruesink, Jennifer², Trimble, Alan², ¹ Northwest Fisheries Science Center, Seattle, WA, USA² Department of Biology, Seattle, WA, USA

ABSTRACT- Non-indigenous smooth cordgrass (Spartina alterniflora) is one of the most conspicuous and widespread non-native aquatic species in Pacific Northwest estuaries. Smooth cordgrass introductions, both accidental and intentional, have occurred in many Washington, Oregon, California, and British Columbia estuaries. In estuaries where smooth cordgrass has invaded, it is widely held to be destructive to habitat and wildlife, and moreover to be a threat to the local economy, founded largely on harvest of marine resources. Despite all of this concern over the most conspicuous impacts of smooth cordgrass, little attention has been given to the role of smooth cordgrass production in the detritus based estuarine food webs where it has invaded. In order to better understand this role, we examined the growth rates and production base of non-indigenous Pacific oysters (Crassostrea gigas) in two Washington coast estuaries (Willapa Bay and Grays Harbor, where smooth cordgrass is absent). We measured naturally occurring stable isotope ratios of C, N, and S in adult and post-settled larval oysters, and several organic matter sources, including smooth cordgrass, eelgrasses, benthic algae, seston, and terrestrial leaf litter. We compared patterns in growth and production base as a function of landscape scale system attributes and found that there were spatio-temporal trends in both growth rates and the diet of Pacific oysters. In addition, it appears as though there is substantial transport of smooth cordgrass derived organic matter from Willapa Bay to nearby Grays Harbor, where smooth cordgrass is absent. Consequently, the presence of smooth cordgrass may have far-reaching impacts on ecosystem processes in Pacific Northwest estuaries.

KEY WORDS: estuary, ecosystem alteration, exotic species, Spartina alterniflora, stable isotope