Impact of Oyster (Crassostrea virginica) Reef Restoration on Benthic Invertebrates and Coastal Birds in a Subtropical Estuary

Abstract

In order to mitigate the degradation of eastern oyster (Crassostrea virginica) reefs in Mosquito Lagoon (ML) along the east coast of central Florida, oyster reef restoration efforts have been in place for over 14 years. These restored reefs are successful in terms of universal oyster metrics (i.e., density, shell height, reef height) and are similar to natural reefs. However, little is known about the impact of this restoration on bird populations. ML provides a habitat for many bird spe-cies, including several listed as “threatened” by the Florida Fish and Wildlife Conservation Com-mission. Many of these birds rely on oyster reefs for foraging and loafing habitats. As benthic invertebrates serve as an important food source for coastal birds, we monitored the abundances and diversity of these organisms on live, restored, and dead reefs. We collected sediment samples from the reef sites pre‐restoration, and one month, six months, one year, two years, and three years post-restoration. We counted benthic invertebrates present in the sediment samples, and sorted them by taxa (polychaetes, amphipods, isopods, gastropods, bivalves, decapods). Benthic invertebrate abundances on restored reefs became similar to live reefs over time (species composition, density), indi-cating that the prey base on restored reefs was similar to that of live reefs within 6 months. A second objective of this study was to determine if restored oyster reefs reach the same abundances, foraging behaviors, and diversity of bird species on natural, live reefs. We conducted monthly bird surveys to assess bird utilization of live, restored, and dead reefs. After three years, the abundances, behav-iors, and assemblages of birds on restored reefs were similar to live reefs.