LB 11-108 - Restoring Eelgrass: First Trial of Dispenser Injection Seeding in North America

The global decline of seagrass biomes, fundamental to the cultural, ecological and economic sustainability of coastal systems is challenging restoration ecologists to develop techniques that are scalable and efficient. Therefore, seagrass scientists are experimenting with various methods to restore declining and fragmented seagrass populations, the foundation upon which the biome is built. In this context the practice of harvesting the yearly seed rain, followed by horticultural methods to prevent the breaking of seed dormancy before planting is driving methodologies to plant seeds of the seagrass, Zostera marina (eelgrass) within restoration sites throughout the range of this species in the Northern Hemisphere. One such practice developed by the Govers Lab, University of Groningen, The Netherlands, at their intertidal research site in the Dutch Wadden Sea, is the system of injecting seeds into the sediment or Dispenser Injection Seeding (DIS), after winter storage in a controlled environment. In the San Juan Archipelago region of Puget Sound in Washington State, the decline of eelgrass in the intertidal region at several locations is identified as a cause for concern by the Washington State Department of Natural Resources, the state agency responsible for the yearly monitoring of seagrass species. As a consequence, the Seagrass Lab, Friday Harbor Laboratories, University of Washington launched a program to restore declining intertidal regions in the Archipelago. In this effort, and after extensive correspondence with the Govers Lab, a plan to trial DIS was advanced. For this experiment and following instruction from Dutch colleagues, we stored seeds, harvested in summer 2022, in a controlled environment that prevented the breaking of dormancy and treated them with Copper Sulfate to prevent fungal infection during storage and after planting. Then from 8 to 13 April 2023, with all team members on site we: 1) combined seeds with sediment in a slurry that was loaded into empty tubes designed to be inserted into a caulking gun; 2) modified the handle of “off shelf” caulking guns with bolts, nuts, and washers to become the injection tool; 3) Calibrated modified caulking guns so the number of squeezes each tube of sediment would dispense would contain three to five seeds and 4) deposited seeds at both 2cm and 4cm depths in m2 plots. In this effort a total of 17,000 seeds were planted at three restoration sites. We will report results during our August presentation.