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Date of Issue: August 18, 2005

Dead to the left, dead to the right ...

red tide dead zone
Photo by: Jack Elka click to enlarge

Depending on if you look at it geographically, vertically or historically, we may or may not have a series of dead-water zones off Anna Maria Island.

 Geographically: The red tide algae Karenia brevis has apparently moved to other locales. Red tide counts of the harmful microorganism were between low- to medium-readings near the Island to high counts at New Pass, south of Longboat Key. It has been called a "dead zone."

 Vertically: There have been reports of "mass mortalities of fish and other animals" on offshore reefs from Sarasota to New Port Richey in the Gulf of Mexico.

 According to the Florida Fish and Wildlife Conservation Commission Marine Research Institute in St. Petersburg, the area impacted is roughly the size of Rhode Island and "organisms affected include dead fish present on the bottom (ranging from bait fish to Goliath grouper) as well as dead sponges, corals, worms, mollusks, crabs, sea urchins, starfish and sea turtles. Bottom visibility was also reported as being significantly reduced."

 And historically: FWRI researchers have announced that they can't find any evidence that the discharge of 117 million-plus gallons of wastewater from the defunct Piney Point phosphate mine in 2003 into the Gulf has had any influence in the present eight-month-long red tide outbreak in local waters.

First, red tide update

 According to Mote Marine Laboratory in Sarasota, "The red tide affecting the Florida Gulf coast has expanded south into Charlotte and northern Lee Counties. While the bloom persists along Sarasota, Manatee and Pinellas counties, the concentrations appear to be diminishing in the northern regions of the bloom. Respiratory irritation and dead fish continue to be reported throughout the area, depending on local bloom conditions and the direction and intensity of the wind."

Dead zone

An area of Gulf bottom of more than 2,000 square miles from Sarasota to the northern Pasco County line has apparently been stressed to the point of near-death by what scientists suspect is an anomaly of the long-term red tide outbreak off our shore. The zone ranges from 3 to 30 miles offshore, and to depths of up to 100 feet.

What scientists speculate happened was that the red tide outbreak was impacted by a thermocline, a layer of warmer water pushing down upon a layer of cold bottom water. The thermocline acts as a barrier and prevents the usual vertical interchange of seawater, causing the red tide organisms to just "hang out" near the bottom for an extended period of time.

The result was the death of hard and soft coral, fish, shellfish and other deep-water organisms.

Although red tide can cause death of marine life, another aspect of its impact lies in the fact that the tiny plants tend to suck up all the oxygen in the water, strangling other critters. Low- and no-oxygen levels were found in some of the so-called dead zone, leading researchers to believe that the lack of oxygen also contributed to the overall kill.

Another facet of the problem is sea turtles. Since Aug. 1, there have been an extraordinary number of dead or sick sea turtles coming ashore from Pinellas County to Sarasota County, including Anna Maria Island.

Anna Maria Island Turtle Watch reports 12 turtle strandings in the past week, nine of which were dead. Pinellas had 35 dead or sick turtles on its beach, and Sarasota had 25.

Turtles have to swim through the bad zone to reach shore.

The slight good news is that a similar incident took place in 1971 regarding red tide and thermoclines, and researchers found that "recolonization of reef fishes was seemingly complete 18-24 months after the red tide and after five years, the fish species composition was basically identical to that prior to the red tide," according to FWRI scientists.

Piney Point

And about that phosphate dumping in the Gulf in 2003 ...

FWRI scientists have sampled the area well offshore of Pasco County in the past few weeks and said they have found no evidence that the past treated wastewater dumping has had anything to do with the red tide.

One researcher told the Tampa Tribune that the phosphate-rich water "was swept through the Florida Keys and into the Gulf Stream."

More red tide info

While Southwest Florida is reeling under the impacts of a red tide outbreak that has lasted since January, federal funding for research into the causes and cures for the blooms have been slashed.

A $7 million grant for five years of study from the National Institute of Environmental Health Sciences was rejected for the upcoming fiscal year. Mote officials said they would apply for funding again next year, adding that the data collected during the recent outbreak would be helpful in the request.

Other grants dealing with red tide and human health were not impacted, although those grants were significantly less than the health science funding source.

For more Red Tide information, please see our Red Tide Update page