Hurricane Harvey disturbance effects on seagrass communities

Hurricanes represent a major form of physical disturbance for coastal ecosystems. These disturbance events may reshape coastal landscapes, driving habitat loss and fragmentation of shallow-water structured environments. One consequence of habitat fragmentation is increasing habitat edge to area ratios. Edge habitats may differ in their value to fauna, as environmental conditions, structural complexity, and predator-prey interactions may all vary relative to habitat interiors. In 2017, Hurricane Harvey, a category four storm, struck Texas and swept over seagrass beds along the Gulf Coast. Using long-term monitoring data, we identified eight sites that experienced severe habitat fragmentation following the storm. This study focuses on the impact of this habitat fragmentation on seagrass faunal communities and the use of edge versus interior habitat at various trophic levels. At each site, we set out minnow traps for 24 hours and collected count and length for the fish and invertebrates within the traps. We found differences in community composition when comparing seagrass habitat edges and interiors. While total organismal abundance and length distributions did not vary, we found higher species richness and evenness in edge habitat versus interior. Specifically, while some species were common across both habitat edges and interiors, there were additional species that were primarily observed on the habitat edges. These species seen only along the edges may represent spill-over from the surrounding matrix as these were species often associated with unstructured bottoms. Interior habitat was largely dominated by one species, Pinfish Lagadon rhomboides, and thus the additional species found along habitat edges seemed to also drive increases in species evenness along seagrass edges. This increase in species diversity along habitat edges in newly-fragmented habitats is consistent with recent findings that suggest that by increasing habitat heterogeneity, habitat fragmentation may often have a positive influence on biodiversity. Future work will reveal whether these same patterns hold at the landscape scale.