Innovative Techniques for Large-scale Seagrass Restoration Using Zostera marina (eelgrass) Seeds

Abstract

The use of Zostera marina (eelgrass) seeds for seagrass restoration is increasingly recognized as an alternative to transplanting shoots as losses of seagrass habitat generate interest in large-scale restoration. We explored new techniques for efficient large-scale restoration of Z. marina using seeds by addressing the factors limiting seed collection, processing, survival, and distribution. We tested an existing mechanical harvesting system for expanding the scale of seed collections, and developed and evaluated two new experimental systems. A seeding technique using buoys holding reproductive shoots at restoration sites to eliminate seed storage was tested along with new techniques for reducing seed-processing labor. A series of experiments evaluated storage conditions that maintain viability of seeds during summer storage for fall planting. Finally, a new mechanical seed-planting technique appropriate for large scales was developed and tested.Mechanical harvesting was an effective approach for collecting seeds, and impacts on donor beds were low. Deploying seed-bearing shoots in buoys produced fewer seedlings and required more effort than isolating, storing, and handbroadcasting seeds in the fall. We show that viable seeds can be separated from grass wrack based on seed fall velocity and that seed survival during storage can be high (92-95% survival over 3 months). Mechanical seedplanting did not enhance seedling establishment at our sites, but may be a useful tool for evaluating restoration sites. Our work demonstrates the potential for expanding the scale of seed-based Z. marina restoration but the limiting factor remains the low rate of initial seedling establishment from broadcast seeds.

Seagrass Halophila ovalis is affected by light quality across different life history stages

“…Then, 4 randomly selected tubes were removed and the number of germinated and viable seeds per tank counted. Germinated seeds were identified if the hypocotyl breached the seed coat, and viable seeds were identified with a squeeze test (Marion & Orth 2010). Viable seeds are capable of germinating under suitable conditions, and non-viable seeds fail to germinate even under optimal conditions (Bradbeer 1988).…”

Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems

“…Our novel insights into these pathogens allow us to optimize sediment conditions. For example, our study shows that anoxia during incubation may reduce infection-which appears to be unknowingly applied in restorations with seed from Chesapeake Bay, where seed germination is highest following storage in low oxygen conditions [31]. Our findings emphasize the need for a mechanistic understanding of such results and call for the development of potentially more efficient mechanism-based methods to reduce infection such as seed treatment with copper-based compounds or phosphonates [66][67][68].…”

“…The material was transported to the laboratory where seeds were removed from seed-bearing shoots. For the experiment, we carefully selected seeds under the microscope with ethanoldisinfected equipment in order to select only fully developed, mature seeds with a hardened seed coat, to mimic natural seed development [31]. Selection was needed, as half of the harvested seeds had not yet matured on the shoot and using these would have biased the outcome of our experiment.…”

A comparative assessment of approaches and outcomes for seagrass revegetation in Shark Bay and Florida Bay

“…For this species, locations with high seed abundances have been identified, large quantities of seed collected and stored for extended periods, and planted with good success (Granger et al 2002;Marion and Orth 2010;Orth et al 2012). Seedbased propagules are potentially a more efficient and costeffective planting unit for large-scale revegetation.…”