Evaluating the combined methods of live planting and seed dispersal in restoration of Zostera marina (eelgrass) in Barnegat Bay, New Jersey by genetic diversity and pedigree analysis of restored populations

Zostera marina (eelgrass) is a near-shore marine plant species that provides essential ecosystem services both as food and refuge for a variety of sea life, as well as a physical anchor for the littoral sediment along temperate coastlines. Due to disease, anthropogenic reductive effects, and recent natural disasters, Barnegat Bay, NJ has seen a reduction in natural populations of the species over the last few decades. Newly restored beds of Z. marina were planted in 2021 and 2022 by a combined method of live transplants and seed dispersal. In 2023, we acquired tissue samples from restored populations with the following objectives: A) test how successful the combined restoration method was at producing thriving populations, B) determine genetic diversity and “genetic health” as partial indicators of restoration success, and C) determine kinship in order to help correlate ancestry and efficacious seagrass growth progression. We found each restored population evinced increased genetic diversity over donor populations, based upon improved observed heterozygosity (mean 0.584), low inbreeding fixation levels (mean -0.146), and higher effective population sizes (mean 2.988). Principal Coordinate Analysis indicated that restored plants are primarily related to live planted donors, with alleles from seed donors in evidence. Cluster Analysis supports that restored individuals have genetic components of all donors, but also suggests environmental selection and genetic bottlenecking have occurred. Statistical analysis confirms the presence of bottlenecks in all restored populations. Overall, results support initial success in restored seagrass meadows. As global declines in seagrass beds continue, with the accompanying loss in genetic diversity, restoration techniques that demonstrate success in ecosystem service recovery and increased genetic diversity will guide practitioners in preservation and restoration of these habitats.