Discovery of a previously unobserved sponge growing on a manmade oyster reef near North Hutchinson Island is prompting a scientist at Harbor Branch Oceanographic Institute to launch a comprehensive new survey of sponges throughout the Indian River Lagoon.
St. Lucie County artificial reef chief Jim Oppenborn had never before found a sponge attached to any of the thousands of restored oyster modules he has deployed in the lagoon over the years, so he was surprised recently to see the motley-looking invertebrate growing in shallow Wildcat Cove.
Oppenborn turned it over to Harbor Branch sponge ecologist/assistant professor Dr. Andia Chaves-Fonnegra and colleague Dr. Cristina Diaz, who identified it as Suberites aurantiacus – commonly found in the Gulf of Mexico, Bahamas, Caribbean and the Brazilian coast, but not in our lagoon.
Sponges, which have been around for hundreds of millions of years, are sedentary creatures that pump and filter large quantities of water and feed on bacteria and tiny plankton. They provide the ecological benefits of filtering pollutants; providing food and shelter for other marine animals; shoring up reefs; and serving as sources of up to half of all anti-cancer drugs in current use.
Now Chaves-Fonnegra is on the hunt to determine whether the sponge – which doesn’t appear on the Smithsonian Institution’s index of 14 lagoon species – is native or exotic, how widespread it is, and whether it benefits or detracts from the lagoon ecosystem.
“It could be possible it was here but not identified,” Chaves-Fonnegra said. “Is this species suddenly here, or was it here before but nobody noticed? We are trying to study it to see how good or bad it could be for the environment.”
The scientist said she and her colleagues and students are embarking on a lagoon-wide survey this summer, with help from other scientists, to find out what sponge species currently inhabit the lagoon; how abundant they are; and what aurantiacus’ role is in the ecosystem. They want to learn what habitats the new sponge lives in, such as sea grass, oyster reefs, sand flats or mangroves.
They also plan to perform experiments on the sponges – initially to see what salinity range they prefer and, if they get funding, to learn whether they harm or help their preferred habitats and how they respond to algal blooms.
The researchers plan to revise Harbor Branch’s inventory of more than 3,500 specimens from the world’s oceans and display aurantiacus in the aquarium at the visitors center.
By the end of the summer, Chaves-Fonnegra hopes to be able to report her findings to the public and help local resource managers like Oppenborn determine how the sponge figures into their lagoon research and restoration initiatives. “It opens a lot of new questions that I am very interested in,” Chaves-Fonnegra said.
