Coral tissue damage that normally heals on its own will not mend when the colonies are near pollution sources on land that release industrial chemicals, fuel oils and other contaminants, a University of Central Florida biologist and several colleagues have found.
UCF associate professor of biology John Fauth and scientists from the National Coral Reef Institute, Broward County Department of Environmental Protection, the College of Charleston and Nova Southeastern University tracked how quickly coral regenerated lost tissue from lesions they created while collecting samples.
Scientists have long been concerned about declining coral reef health off the southeastern Florida coast, in the Florida Keys and worldwide. The World Research Institute's Reefs at Risk program has listed coastal development and treated wastewater discharge as chronic problems along Florida's southeast coast.
The loss of coral harms natural reef ecosystems and can hurt Florida's tourism economy if divers decide to go elsewhere. Reefs also help to protect coastal areas from hurricanes, as they break up storm surge in the same manner that sea walls do.
"We're losing places where animals can hide and fish can feed," Fauth said. "And reefs where people dive are being degraded."
Tissue samples from mustard hill coral were taken from eight Broward County sites, including near-shore and offshore locations at each of four sites: a City of Hollywood treated wastewater outfall, the Port Everglades inlet mouth, a second outfall next to a mouth of the Hillsborough Inlet and control sites away from outfalls and inlets.
Fauth and his colleagues used the equivalent of blood tests on humans to identify likely causes of low coral vitality near wastewater discharge pipes and the Port Everglades inlet. Coral that were growing near both areas were unable to repair tissue damage, while coral colonies at control sites healed the small areas where the scientists removed tissue for analysis.
Coral growing near land-based sources of pollution were found to be stressed by chemical contaminants, including elevated levels of fungicides, industrial chemicals and fuel oils.
The total tissue loss was highest near the City of Hollywood wastewater outfall and was moderately high at the Port Everglades and Hillsborough Inlet stations. Coral in those areas also regenerated either at an extremely slow rate or not at all, indicating that conditions there were poor for coral growth and reproduction.
High levels of a protein known as GRP 75, or mortalin, were found in samples near the Hollywood wastewater outfalls and in the Florida Keys National Marine Sanctuary. Excessive levels of ubiquitin, a small protein that attaches itself to already damaged proteins and causes them to degrade more, also were found at those sites.
At three offshore sites, elevated levels of a multidrug resistance protein were found. That helps the coral defend itself against contaminants, but it is metabolically costly for coral to produce, leaving less energy available to repair damaged tissue.
Fauth's team is sharing data with Professor Michael Risk of McMaster University in Ontario, Canada, and marine ecologist Brian LaPointe of the Harbor Branch Oceanographic Institution in Fort Pierce. Risk and LaPointe used ratios of stable isotopes of nitrogen as tracers of sewage levels. Higher values equate to larger amounts of sewage in an area. Risk and LaPointe found higher levels of the tracers than in any other area of Florida that they have studied, which Risk described as a "real cause for concern."
Nitrogen pollution can be caused by the discharge of treated wastewater effluent, and it leads to poor coral growth and algal blooms.
Coral samples in Fauth's project were analyzed at Haereticus Environmental Laboratory in Amherst, Va.
"We're doing the same thing as a medical examiner," Fauth said. "It's possible that corals are being stressed by pollution, and we're trying to find out what stresses them and how it's affecting coral health."
If the researchers can determine the specific causes of pollution that are harming coral, it then will be up to governments, organizations and residents to decide whether it's worth the cost of solving whatever problems are discovered. Solutions include additional treatment of storm-water runoff and wastewater discharges and enforcing regulations on industries that are likely causing pollution.
Tom Evelyn | EurekAlert!
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