SEA GRANT STORY TIP SHEET FOR MARCH 24, 1999
BROWN TIDE FOUND IN INLAND BAYS
Delaware's Inland Bays already have two harmful algal species, Pfiesteria and red-tide dinoflagellates. Now a third harmful algal species, Aureococcus anaphagefferens, that causes brown tide, has been identified in the Inland Bays. David Hutchins, a Delaware Sea Grant researcher, and Bruce Richards, director of the Center for the Inland Bays, collected samples this winter and found brown tide in Little Assawoman Bay, and even higher levels in Assawoman Bay in Ocean City, Maryland. Because the two are connected, it is possible that Assawoman Bay is the source of brown tide found in Little Assawoman Bay. In June 1998 surface water was collected from 13 sites, including Indian Rivers, Rehoboth, and Little Assawoman bays. "The brown-tide organism was definitely already present in Little Assawoman Bay. No brown tide cells were observed in eleven samples from Indian River and Rehoboth bays," Hutchins states. Brown tide kills by rapid growth that can disrupt entire estuarine communities. "Laboratory studies are currently being conducted with cultured brown tide growing in water collected from several sites in the Inland Bays. We hope to be able to give managers some idea of the potential for harmful algal blooms in the bays, and the conditions under which they are likely to happen," Hutchins says.
CONTACT: David Hutchins, Delaware Sea Grant, (Lewes, DE), (O) 302-645-4079;
E-mail: [email protected].
SPONGE OVERGROWTH THREATENS CORAL REEFS
A great diversity of sponge species inhabit the Caribbean. Lately, however, some sponges of the Cliona aprica - C. langae - C.caribbea species complex have been observed to overgrow and kill several species of coral colonies. According to Ernesto Weil, a Puerto Rico Sea Grant-funded researcher, "The sponges are covering extensive areas of reef substrate, killing large colonies of major reef building species." Weil states, "Very little is known about the biology and ecology of these sponges and their growth habits. The epidemic growth of these sponges may be related to eutrophication or nutrient enrichment of reef habitats, and/or high sedimentation rates. The imbalance might also be caused by a lack of predators that might otherwise keep sponge populations in check, or it may simply be a natural process in these communities." According to Weil up to 12 important reef building coral species in the Caribbean seem to be especially vulnerable to the sponge invasions. Weil hopes through his research to determine "the rate of coral mortality with relation to sponge growth, gauge the geographic distribution of the problem and determine what exactly is causing the apparent increase in the sponges' monopolization of the substrate." Most reefs today are stressed beyond their capacity to recover, and the sponge problem may be another source of concern for the future of coral reefs.
CONTACT: Dr. Ernesto Weil, Coral Reef Biologist, (Puerto Rico), (O) 787-899-2048 ext. 241;
E-Mail: [email protected]
DREDGED MUD PROVIDES GREENER PASTURES FOR LIVESTOCK, WILDLIFE
Each year the U.S. Army Corps of Engineers dredges up enough dirt from Texas' coastal waters to cover a city block with a 14,000-foot-high mountain of mud in order to keep canals and ship channels open. This mud flows onto waterfront land and has created negative feelings among coastal ranchers who feel that this mud destroys their property and livelihoods. A Sea Grant-funded study by Texas A&M University soil and crop scientists has shown that this mud can actually provide greener pastures for livestock and wildlife. They have discovered that by lowering the high salt content of dredged mud and planting salt-tolerant grasses, they can produce a higher-quality grass for livestock. "We've proven that we can restore production on these sites at a much faster rate than was thought before," said David Bade, professor and extension forage specialist with the Texas Agricultural Extension Service. Bade said, "The bottom line is that a rancher should view dredging on his property as an opportunity to enhance both grass production and the well-being of his livestock, especially during the wet season." CONTACT: David Bade, Sea Grant Researcher, (Bryan, TX), (O) 409- 845-6800,
E-Mail: [email protected]
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