Meeting Abstract

S10.9  Wednesday, Jan. 6  Ecosystem engineering in Florida’s estuaries: mangrove and oyster ecotones over a gradient of anthropogenic disturbances DONNELLY, M.J.*; WALTERS, L.J.; University of Central Florida; University of Central Florida mdonnelly@knights.ucf.edu

Anthropogenic disturbances have altered the structure and diversity of mangrove and oyster ecosystems. Although not commonly found together, tropical mangroves and reefs of the temperate oyster Crassostrea virginica have overlapping distributions in Florida. These two ecosystem engineers create a unique connected habitat, supporting a diverse assemblage of organisms. Here, we discuss what has happened in the Indian River Lagoon where humans have modified topography by increasing reef and marsh elevations, which in turn has eliminated native ecosystem engineers and respective communities and increased non-native invasions. Next, we discuss the effectiveness of restoration on these engineers by leveling both habitats back to pre-disturbance elevations. With oysters, boat wakes create 1m high dead margins composed of disarticulated shells on which aquatic diversity plummets from 149 to 0 species and only terrestrial plants are able to establish. Leveling dead margins and providing recruitment substrate re-established biodiversity to control levels within months. With mangroves, marshes were impounded for mosquito control by creating dikes 1m above mean high water, reducing mangrove recruitment and facilitating terrestrial plant invasions. During restoration, dikes were leveled and all existing vegetation removed. Our 4-year monitoring program documented recruitment of mangroves, fiddler crabs, birds and fishes to restored impoundments. As plant and invertebrate communities develop, increased diversity of birds and fishes was observed. Due to their importance as ecological engineers, restoring mangrove and oyster habitat can have cascading effects throughout the estuarine system and benefit a variety of organisms.