According to this story, the red tide currently floating off the coast of Sarasota "has not killed fish or caused respiratory problems on Siesta Public Beach, Sarasota County's biggest tourist beach."

Um, wrong.

There were hundreds, maybe even thousands, of dead fish on that particular beach yesterday -- mostly the ones in the cell-phone pic above, but also some pufferfish (pictured after the jump) and pinfish. About an hour up the road, snook have also been dying, apparently because of an underwater explosion. We think it bears repeating: It's hard out there for a fish.

By the way, the toxin involved in some red tides has a long and storied history involving, among others, Richard Nixon and the CIA. Find out about it here, or after the jump.


A more insidious aspect of the colourful history of saxitoxin has to be its involvement in covert government operations and in chemical warfare. Saxitoxin is about 1000 times more toxic than a typical synthetic nerve gas such as sarin, and it is perhaps not surprising that in the 1950s, the CIA began experimenting with it, reportedly using it in suicide capsules provided to its agents (notably U-2 pilot Francis Gary Powers).

In 1970, President Nixon ordered the CIA to destroy its entire stock of saxitoxin, painstakingly collected over several years, as part of the US commitment in accordance with the United Nations agreement on biological weapons. Nowadays, saxitoxin and ricin are the only two natural toxins classified as Schedule 1 Chemical Warfare Agents. However, in 1975 William Colby, the CIA Director, revealed to Congress that they still possessed over 10 grammes of the material in downtown Washington. Luckily, this supply of saxitoxin was eventually distributed to scientists and medical researchers under the auspices of the National Institutes of Health (NIH).

In connection with this, STX, like many other naturally occurring toxins, has been an indispensible tool in medical research. It is a potent and extremely selective sodium-channel blocker, having no effect on potassium or calcium channels, or the flux of chloride ions, or indeed on acetylcholine release (whereas other marine toxins have similarly selective effects on these aspects of nerve function). Saxitoxin has been used for the labelling, characterisation and isolation of various sodium channel components, and this has opened up new avenues for the study of various nervous disorders.