Leveraging Native Cockles for Enhanced Eelgrass Seeding Success

Paul Anderson, San Juan Islands Conservation District

Eelgrass plays a vital role in the Salish Sea providing critical species habitat, preventing coastal erosion, improving water quality, and contributing to shellfish and human health by reducing pathogens in seawater. While the San Juan Islands historically had robust eelgrass meadows, the islands have recently experienced alarming local declines, with near-total losses in some areas. This project will test the success of Bivalve-Facilitated Seeding, in which eelgrass seeds are glued to bivalves, such that they are released into the sediment as bivalves burrow. Bivalves benefit seeds by aerating the sediment, thereby removing sulfide, a chemical toxic to eelgrass. This method has been deployed elsewhere with favorable results. This work will compare success rates of these methods with others eelgrass seeding techniques including Broadcast Seeding, Dispenser Injection Seeding, and Hessian Bag Seeding. Ultimately it will evaluate the initial establishment of seedlings over time and the influence of environmental variables on the success of each planting method. Finally, the investigators will analyze the cost of each planting method.