PNNL

Abstract

Seagrass ecosystems are extremely valuable for supporting a wide variety of ecosystem functions and values, and are under constant threat of impairment and loss. Restoration of these systems has moved beyond the research stage and is now considered a tool that coastal managers can use to offset damages and restore coastal ecosystems. However, restoration of seagrass ecosystems is complex. Working in collaboration with the Washington State Department of Transportation, U.S. Corps of Engineers, and King County, we have developed an integrated approach to improving the success of eelgrass restoration projects in the Pacific Northwest. The approach uses a conceptual model, site assessment, field and laboratory experiments, mapping (using underwater videography and side scan sonar), and a refined monitoring and management scheme to maximize the probability of project success. The conceptual model clearly relates the project goal to the factors affecting development of the system. For eelgrass, the critical factors include light, salinity, temperature, substrata type, nutrients, and wave and current energies. The model also provides a basis for monitoring by highlighting the key factors that might explain failure to meet performance goals. A site assessment relative to known ranges of these factors, along with small-scale field trials, help verify site suitability for eelgrass restoration. The adaptive management plan specifies the performance levels and time frame for development of the system along with alternative actions if the system is not meeting these goals. This approach reduces uncertainties in eelgrass restoration while improving cost-effectiveness, and may have broad applicability to other regions.