Oh Shoot! Initial Development of Gelatin-Based Adhesive to Facilitate Seagrass Restoration Through Biological Partnerships

Abstract

Seagrass meadows are among the most valuable coastal ecosystems, providing important services such as carbon sequestration, shoreline stabilization, water filtration, and habitat for fisheries species. Despite their ecological importance, seagrass ecosystems have declined worldwide due to coastal development, nutrient pollution, sediment disturbance, and climate driven environmental change. When natural recovery does not occur after disturbance, active restoration is often necessary. However, seagrass restoration remains expensive, labor intensive, and is prone to failure, which limits the spatial scale at which restoration projects can be implemented. Seed based restoration has emerged as a promising strategy for expanding restoration efforts because seeds can be collected and distributed across larger areas than transplanted adult plants. However, seed deployment presents challenges. Seeds can be displaced by currents, buried too deeply, or lost to predation before they germinate. Improving seed retention and early survival is therefore critical for increasing the success of seed-based restoration. This project explored a restoration approach designed to harness ecological facilitation between seagrass and bivalves. Clams can influence sediment conditions through burrowing and nutrient release, which may enhance seagrass growth and help bury seeds at suitable depths for germination. To take advantage of this interaction, we developed a gelatin-based adhesive intended to temporarily attach eelgrass (Zostera marina) seeds to juvenile clams (Mercenaria mercenaria). If effective, burrowing clams could naturally move attached seeds into the sediment while improving nutrient availability. We conducted a field experiment near Harker’s Island, North Carolina to test whether the adhesive affected seed germination and early growth. Four treatments were established: seeds only, seeds with adhesive, seeds with clams without adhesive, and seeds attached to clams using adhesive. Each treatment was replicated ten times using groups of twenty seeds. Plots were planted in October 2025 and monitored biweekly through April 2026. During each monitoring event we recorded the proportion of plots that germinated, the number of shoots present, and the maximum shoot length in each plot. Results showed that treatments involving adhesive produced fewer shoots than treatments without adhesive, indicating reduced early seed survival. However, once seeds germinated, shoot growth did not differ among treatments. Maximum shoot length increased similarly across all treatments over time, suggesting that the adhesive did not affect plant growth after establishment. The lower survival observed in adhesive treatments likely resulted from stress during the gluing process rather than from the adhesive material itself. Seeds may have experienced heat exposure during adhesive preparation or partial desiccation while they were handled outside of water. Both factors could have reduced germination success. We also did not detect a facilitative effect of clams, possibly because the density of clams used in the experiment was too low to generate measurable changes in sediment conditions. Overall, these results highlight the importance of minimizing stress to seeds during handling and deployment in seed-based seagrass restoration. While adhesives may still provide a useful tool for pairing seeds with beneficial organisms, improved application methods that reduce heat exposure and handling time will likely increase success. Continued refinement of these techniques could help develop more scalable and cost-effective approaches for restoring seagrass ecosystems.