Public Release: 

DNA may hold clues to Red Tide origins

Texas A&M University

COLLEGE STATION, August 14, 2002 - Where do the Red Tides invading Texas coastal waters originate? That's what Texas A&M University oceanographer Lisa Campbell is trying to find out as she attempts to use DNA markers known as microsatellites to identify the genetic diversity with blooms of Karenia brevis, the species of phytoplankton causing Red Tides.

Red tides occur unpredictably in the Gulf of Mexico and result in fish kills and, sometimes, human illnesses.

"We are now focusing on developing tools to examine diversity within bloom populations and to fingerprint populations, which should enable us to trace them to their sources," Campbell said.

Campbell and co-investigator John Gold of the Department of Wildlife and Fisheries Science in the College of Agriculture are the recipients of a three-year grant from the Environmental Protection Agency (EPA) to develop hypervariable DNA microsatellite markers for the algae. In the course of the project, part of the national ECOHAB program, the researchers will use the DNA markers to compare algae isolated from throughout the Gulf of Mexico. Ultimately they will try to pinpoint the geographic points of origin of those that cause particular red tides.

"Previous studies have revealed that blooms of diatoms consist of a number of different strains, or clones, that are highly diverse with regard to growth rates," Campbell said. "We're asking: Is such high diversity within a bloom also true for dinoflagellates?

"We know that Karenia brevis cells can exist under a wide range of conditions. We also know that some strains can grow faster than others and some are more toxic than others. So it is important to know under what conditions the more toxic strains may bloom."

Campbell and Gold will be examining specimens isolated from water samples collected by Texas Parks and Wildlife scientists at seven locations along the Texas coast.

Campbell will carefully pick out individual cells under a microscope to establish clonal cultures in the lab. Each culture will be examined for differences in physiological and genetic properties. Samples collected and analyzed over the course of a bloom will allow estimation of genetic variation within a bloom. Campbell and Gold speculate that a high level of genetic diversity may allow populations to bloom in response to appropriate environmental conditions.

"Dr. Gold and I hope that by identifying diversity within populations of toxic algae we can help to predict when and where red tides may occur along the Texas coast," Campbell said.


Additional Contact Information:
Lisa Campbell,

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