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ODU's Butler and UF Scientist Creating Marine Housing by Restoring Sponges

Shrimps, lobsters and other marine animals in Florida Bay are the projected beneficiaries of a seabed housing project that has been undertaken by scientists from the University of Florida and Old Dominion University.

Marine sponges may not look like apartment buildings, but these puffy filter-feeders provide one of the few safe places to live for many sea creatures.

In 2007, harmful algae blooms killed sponges in large tracts of the shallow lagoon, where fresh water draining from the Everglades meets the Gulf of Mexico. The project scientists now are trying to restore the population by cutting up healthy sponges, then planting the cuttings in affected areas to grow and reproduce.

The results of the study will lay the groundwork for larger restoration efforts that would boost populations of economically important seafood species that depend on sponges, help Florida's commercial sponge industry and improve water quality, said Don Behringer, a research assistant professor with UF's Institute of Food and Agricultural Sciences.

"Sponges don't get as much attention as other, more charismatic marine species," said Behringer, co-leader of the project. "But in hard-bottom habitats they dominate the biomass and are important to ecosystem health."

The other project leader is Mark Butler, professor of biological studies at ODU. The two collaborated on research in south Florida and the Caribbean in the early part of the decade when Behringer was a Ph.D. student of Butler's. One of their widely publicized studies found that Caribbean spiny lobsters can swiftly detect when a mate is infected with a lethal viral pathogen and shun the mate in a practice akin to quarantine.

In Florida Bay, the seabed is a mixture of hard-bottom areas, sea grass meadows and almost featureless sand and mud areas. Within the hard-bottom, marine sponges, some of them several feet in diameter, are the dominant source of structure and shelter. In parts of the bay the animals were so abundant prior to the algae blooms that they were estimated to filter all surrounding water every three days, straining out bacteria they consume as food.

The 2007 algae blooms affected about 200 square miles of the 1,100-square-mile bay, wiping out nearly every sponge in some areas. Similar blooms may have occurred for at least a century, but hard evidence is lacking, Behringer said.

Armed with $157,000 in grants from The Nature Conservancy-National Oceanic and Atmospheric Administration Community-Based Restoration Program, and Everglades National Park, the researchers will try to reintroduce sponges in the Everglades National Park and the Florida Keys National Marine Sanctuary areas of Florida Bay.

In this feasibility study, four species will be used: loggerhead and vase sponges, large species that provide habitat for sea animals; and glove and yellow sponges, important to Florida's commercial sponge fishing industry, said Butler.

Florida is one of the world's major marine sponge providers, producing 60,000 to 70,000 pounds annually.

Butler said the exact methods used for placing sponge cuttings are still being developed, but it's likely that small sections will be attached to weighted bases and placed on the sea floor. For the next three years, researchers will assess the cuttings' survival, growth and reproduction.

The project came about partly because sponges are little-studied, Butler said. He has studied lobsters for 25 years and appreciates how sponges provide habitat for the crustaceans.

Another reason is that sponge populations spread slowly-larval sponges are free-swimming, but anchor after a few hours and spend the rest of their lives in one place.

This article was posted on: September 8, 2009

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