Colonization of Robinson Preserve: An Evaluation of Restoration Efforts in an Estuary in Tampa Bay, Florida (Extended Abstract)
Mangrove forests are ecologically important coastal ecosystems found throughout much of the tropics and subtropics. Worldwide, mangroves are experiencing losses of 1–2% per year (Lewis 2005). Many of Florida’s mangrove habitats, including those in Tampa Bay, have been severely impacted by development with statewide losses of more than 75% (Lewis 2005). Such habitat loss can have major impacts on local fisheries. In Florida, 80% of all commercially or recreationally targeted marine species depend upon mangrove estuarine areas during some stage of their life cycle (Lewis et al. 1985). Robinson Preserve is a 197-ha preserve and one of the largest salt marsh and mangrove restoration efforts in Tampa Bay. Originally a coastal wetland, the property was ditched, drained, and used for agriculture. In 2006, reconnecting the property’s existing water bodies to the Manatee River, Perico Bayou, and Palma Sola Bay restored tidal flow. Existing old growth mangroves were preserved and new mangroves were expected to colonize in areas with high propagule pressure (i.e., areas where large amounts of mangrove seeds/seedlings are frequently deposited by currents and tides). Upland and salt marsh vegetation were planted; however, aquatic flora and fauna were left to colonize from neighboring populations.
Evaluation of coastal restoration efforts often focuses on vegetation (coverage, density, and structure, etc.), and the time of evaluation is usually shorter than the time required for function to be restored (Simenstad and Thom 1996). Lewis and Gilmore (2007) noted that fish populations within restored marshes and mangroves may recover to levels similar to reference sites in both species composition and density within 5 years. The waters of Robinson Preserve were sampled seasonally from 2008 to 2013 to evaluate the success of restoration activities, and colonization by fish. The preserve was divided into four regions based on water flow and connectivity to surrounding water bodies (1: mixing zone, 2: Palma Sola Bay and Perico Bayou, 3: freshwater upland inputs, and 4: Manatee River). Sampling was distributed throughout each zone with effort proportional to zone size. Each zone was sampled using multiple gears (21.3-m center-bag seine, 6-m beach seine, 2.1-m cast net, and a 0.36-m bottom frame dip net) to effectively target species of varying sizes and habitat preferences. The proportional effort of each gear was similar among the different zones. Sampled habitats were classified by shore type.