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PAUL SWIDERBiologists say a recent fish kill in area bays and backwaters was caused by an algae, but not the notorious Red Tide.
GULFPORT - A budding marine mystery making the rounds in coastal Pinellas County may have a benign explanation more in human nature than Mother Nature.
When Gulfport's harbormaster, Dennis Frain, went to work Oct. 15, he didn't notice anything unusual in the marina until he opened the bay-fed tank of shrimp he keeps to sell as bait: all the shrimp were dead. Then he noticed dead fish popping up in the marina. Frain said he thought it was just his turn at Red Tide, considering he'd gone all year without the organisms.
A few days later, at the marina during low tide, he noticed dead crabs and even oysters, as well as an odor like nothing he'd ever smelled before. When the water was low, he could also see a black film on the seawalls, another oddity from his experience. Fishermen told him the effects seemed to end at the mouth of the marina, which would be odd for Red Tide.
Fearing dangerous contamination, Frain called the Pinellas County Department of Environmental Management, which had gotten similar calls from South Pasadena, Madeira Beach and North Redington Beach. The county sent a researcher to check the water. Frain said they found no Red Tide, no sewage, nothing unusual, except an extremely low oxygen level in the water, which was enough to explain the dead animals. Still, with no explanation as to why oxygen levels were so low, he shut down the marina's boat ramp and told customers to stay out of the water.
"This is something we've never seen before," he said. "We wanted to protect the public."
County officials contacted the Florida Department of Environmental Protection, which monitors marinas, and those officials contacted the Fish and Wildlife Research Institute, the Fish and Wildlife Commission's research arm. The reports all made mention to a blue-white sheen on the surface of sheltered waters like marinas. But rather than discovering a novel phenomenon, the institute found a normal occurrence made abnormal by human perception.
"This is probably an observer effect," said Jeremy Lake, spokesperson for institute. "It's a regular occurrence that is unusual for people observing it, but not for the aquatic community."
Lake said his scientists tested water samples from Gulfport and South Pasadena and found evidence of several kinds of naturally occurring algae that had bloomed suddenly because of a relatively unusual set of circumstances. He said those sheltered waters had had just the right amount of rainfall, the right set of temperatures and just enough cloud cover to create conditions these algae liked. That the protected areas don't get flushed well with seawater made for an algae cocktail dense enough that, when the plants died off, their decay consumed all the oxygen, the lack of which suffocated animals. The sheen was left over from the algae.
"There wasn't anything unusual about it," Lake said.
Lake said the die-off is unrelated to Red Tide and unrelated to the dead zone that's been killing wildlife during the summer offshore in the Gulf of Mexico. In fact, he said that dead zone, caused by Red Tide trapped near the sea bottom, is breaking up after Katrina stirred the gulf on its way to New Orleans.
Still, it all seemed very strange to Frain, with 22 years of experience on the water. The DEP told him it was safe to reopen the marina, so he did. But he said fishermen had the same perception he had, that something truly odd was going on.
"I guess there's different types of algae," he said, noting that the scientists deal with these events more routinely than he does. "They see it every day.
"Still," he said, "I've never seen anything turn the seawalls black."