Sponges are found throughout the waters of the Florida Keys and are among the most visible residents of the hard-bottom habitats typical of the region. These animals are filter feeders that attach to hard surfaces and continuously filter large volumes of water through their pores to capture food, removing particulate matter such as plankton and nutrients. They’re essential to healthy marine ecosystems – they alter the water chemistry by cycling nutrients and provide nursery habitat for important fisheries species such as spiny lobster, stone crab, and bonefish. They’re home to many marine critters including brittlestars and several species of shrimp. Snapping shrimp are known to inhabit open spaces within some sponges, and the loud popping sound they make with their claw may act as a cue to other species seeking habitat.
In recent years, a series of harmful algal blooms has had great impact on local sponge communities, changing the balance of marine ecosystems. There are over 70 species of sponges in the Florida Keys. Once thriving, many sponges have died over wide areas of the Middle and Upper Keys in Florida Bay. Since sponges grow slowly and are limited in dispersal during their larval stage, there is a lengthy recovery time for sponge communities after die-offs.
Elliot Hart of the Florida Fish and Wildlife Commission laying out sponge cuttings in the Sandfly Key nursery. © The Nature Conservancy (Jennifer Stein)
The Nature Conservancy and researchers from University of Florida, Old Dominion University and Florida Fish & Wildlife Conservation Commission (FWC), Bonefish and Tarpon Trust, and the Florida Keys Environmental Fund have partnered to study sponge community restoration. The partners have propagated sponges both at natural sites, where existing sponges are cut and monitored for recovery and the pieces are placed locally and monitored for growth, and in underwater nurseries, where seven species are grown from locally collected sponges for future transplantation to the degraded areas of Florida Bay. Sponges are transplanted to restoration sites and monitored for benefits to water quality including impacts on plankton and nutrient cycling, creation of habitat for other species, ability to become self-sustaining, and improvement of reproductive success. As of February 2017, between 6,000-7,000 sponge pieces have been placed out in natural habitat, and another 6,000 are growing in four sponge nurseries. The program is led by the FWC's Fish and Wildlife Research Institute, Dr. Mark Butler of Old Dominion University and researchers from Florida SeaGrant and FWC, with the objective of determining the potential effectiveness of large-scale sponge restoration.
Currently in the second year of the partnership, researchers continue to expand existing nurseries and evaluate their success in an effort to develop the most effective and productive methods for sponge growth.