Award: OCE-1906635

Seagrasses, flowering plants found in marine habitats, are critical components of coastal ecosystems, and may be decidedly vulnerable habitats in the context of hurricanes due to their shallow distribution. During storm passage, physical removal of plants can have lasting impacts on associated fauna which depend on seagrasses to provide structurally complex, food-rich habitat. Seagrasses are also sensitive to changes in water quality conditions that shift in the days-months following landfall such as low salinity and low light availability due to high turbidity from sediment resuspension. Impacts on seagrass meadow species composition may disrupt critical ecosystem services such as habitat provision for fisheries species. Broadly, disturbance remains a major organizing force in marine communities with the potential to shape biodiversity and ecosystem dynamics. To gain a greater understanding of hurricane disturbance impacts on coastal systems, with particular interest in the factors that promote or dampen seagrass ecosystem resilience, we documented losses in seagrass habitat structure and composition (including seedbank), following the impacts of Hurricanes Florence and Dorian on seagrass meadows in southeastern North Carolina. Results indicate that the impacts of both hurricanes were minimal to seagrasses in this region, as there was no significant difference in biomass, density, percent cover or reproductive effort pre- and post-storm in either Zostera marina (eelgrass) or Halodule wrightii (shoal grass). There was also no difference between seagrass species that reproduce primarily via seeds in NC and form seed banks (eelgrass) vs those that only reproduce through vegetative growth and do not produce a seed bank (shoal grass). The trend was observed following both Hurricane Florence and Dorian. Meadows with greater plant diversity, as noted by the presence of both shoal grass and eelgrass, did not have a greater seed bank retention (% retention from August to December 2018 and 2019) than those with lower plant diversity. This finding was unexpected as it was hypothesized that the cover found in more diverse meadows would help keep the seedbank intact during and after the storm event. Eelgrass only meadows die-back every year in August which removes above ground cover. The lack of a response between meadow types maybe related to a potential reduction in the number of seeds deposited into the seed bank in sites where eelgrass density, and therefore flowering shoot density, is reduced. Overall seagrass meadows in southeastern NC were more resistant the potential negative effects of multiple hurricanes than expected. As a result, the impacts of increased storminess in this region predicted to occur as part of climate change may be more limited than expected. However, it should be noted that hurricane impacts from storms with wind speeds > 98 mph were not evaluated as part of this study and may result in greater impacts than shown here. Last Modified: 06/10/2022 Submitted by: Jessie C Jarvis