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RED TIDE - USA (TEXAS)

A ProMED-mail post
<http://www.promedmail.org>

Date: 25 Sep 2000
From: H. Larry Penning, MD <bevpenn@fgi.net>
Source: The Corpus Christi Caller Times, 25 Sep 2000 [edited]

Texas state agencies are closely monitoring what may be the largest concentration of red tide in the Gulf of Mexico since 1986 when a strain passed through the area, killing more than 22 million fish in a 4-month period.

Dave Buzan, spokesman for the Texas Department of Parks and Wildlife Kills and Spills Team, said locally, the algae have reached high enough concentrations to be seen by the naked eye and cause respiratory irritation in humans.

The current outbreak already has resulted in millions of dead fish, he said. "We do not have an accurate number yet," said Buzan. "But we are estimating several million fish have been killed so far."

According to the Texas Parks and Wildlife daily Internet update, biologists observed red tide on Sunday in the Corpus Christi Bay near the downtown area. They also observed red tide in the Oso Bay and near the Port Aransas jetties. Since Labor Day weekend, streaks of the algae were spotted in the Gulf of Mexico near Galveston and in the west end of Matagorda Bay.

Buzan said one visible bloom off Matagorda Bay appeared on Sept. 18 and now spans more than a 70-square-foot area. "It is so big it can be detected on satellite imagery," Buzan said.

Red tide is a high concentration of microscopic algae producing a toxin, affecting the central nervous system of fish and killing them. While the fish kills usually consist of schooling species, such as mullet and menhaden, the algae has a domino effect on other marine life.

"Some (fish) do not die from red tide," said Wes Tunnell, director of the Center for Coastal Studies at Texas A&M University-Corpus Christi. "They die from lack of oxygen."

Blooms, or high concentrations, usually come up along Gulf beaches and less frequently into bays and estuaries. They can become so dense the water turns a reddish-brown and causes the oxygen levels in the water to drop far below normal. Usually, smaller fish die off first, but larger fish suffer as their food supply dwindles, Tunnell said.

The toxins can become airborne, causing human respiratory problems such as respiratory nose, throat and eye irritation.

The Department of Health also warns people can get neurotoxin shellfish poisoning from eating clams, mussels, whelks and oysters contaminated by red tide.

The department warns the public against harvesting for personal consumption. Red tide poison symptoms include nausea and dizziness lasting for several days. Seafood such as crab, shrimp and fish should be safe from contamination.

In Galveston Bay, commercial harvesting of oysters has been shut down since Sept. 5 because of red tide. The Texas Department of Health's Seafood Safety Division officials are monitoring the situation locally to see if similar restrictions will need to be issued in the Coastal Bend. Oyster season doesn't open in Corpus Christi until November.

"We will be looking to determine if it is safe to open for oyster season," said Kirk Wiles, director of Seafood Safety. "We will have to see if there are any problems at that time."

For more information on red tide, visit the Texas Parks and Wildlife Web site at www.tpwd.state.tx.us. or by calling (800) 792-1112.