The Doctor Weighs In

Brian Klepper

Everyone in my Northeast Florida beachside neighborhood has been coughing as soon as they step outside. The mailman wears a breathing mask. People with respiratory problems have been warned to stay inside. Local acute care centers and hospital emergency departments are standing by for patients. The beach is nearly empty of the walkers, sunbathers and fishermen who normally inhabit it.

A few days ago our beach was afflicted with a red tide. In this area, red tides are blooms of the highly toxic alga Karenia brevis, a particularly nasty single-celled, photosynthetic organism. Each cell has two flagella that it uses to swim in a spinning motion. More to the point, though, K. brevis naturally produces potent neurotoxins called brevetoxins. These brevetoxins are responsible for large kills of marine life, as well as human respiratory distress when the toxins become airborne particulates.

High concentrations of K. brevis turn the water a pinkish-red. So far, I haven't seen that here, but my area has only moderate concentrations of the organisms. Just to the south, the bloom is much worse.

Still, the miles of coast where I walk -  I live on a barrier island on the Atlantic coast - are littered with thousands of dead fish, mostly bottom dwellers. The majority are small, but some are sizable. I found a 30 pound grouper this morning, as well as a big sea turtle, probably 100 pounds. In 2005, a red tide killed a bottlenosed dolphin (Tursiops Truncatus) pod in the Gulf near Naples, poisoned by the fish they had just eaten.

 A Red Tide Off La Jolla, California

Red tides are a nearly annual event in the waters off Florida's Gulf coast, between Tampa and Naples (the lower portion of the state's west coast). There's some evidence that northeast Florida's bloom originated there, but was transported here by the currents that push water up from the Carribean. In fact, the early Spanish conquistator, Álvar Núñez Cabeza de Vaca (1490-1557), reported seeing one during his adventures in what is now the Texas Gulf coast. (There's also some speculation that a red tide was responsible for the first of the Egyptian plagues, blood, that led to the freeing of the Hebrew slaves in the Passover story.)

Red tides are not limited to ocean waters. They can occur in fresh water lakes, and can be precipitated by man-made influences, like sewage.

Even though this is a local environmental disaster, especially for the wildlife, for us the inconvenience is nominal. I think of the millions of creatures who live just off our beach - the fish, dolphins, whales, sharks, shrimp, and micro-organisms  - and pity their plight as the waters they live in and the foods they normally eat are poisoned.