A similar mechanism to those described above has been found for fish deaths due to algae:
QUOTE: ...Pfiesteria [the algae species in question] has been implicated for years in a series of otherwise unexplained episodes of mass fish death throughout its range from roughly Delaware to Alabama, particularly in the Neuse River in North Carolina and the Chesapeake Bay. The single-cell organism can experience explosive growth resulting in algae blooms in coastal waters. While it has been suspected not only in fish kills but in incidents of human memory loss and other environmental and health-related effects, no one has ever conclusively identified the actual mechanism...
Moeller's team established that the Pfiesteria cell can produce a copper-containing exotoxin--a toxin produced external to the cell itself--possibly as a mechanism to protect itself from copper in the environment. When exposed to sunlight or other environmental factors that can destabilize it, the toxin rapidly breaks down into short-lived free radicals, highly reactive chemical species believed to be the actual lethal agents. To observe the entire chain of events requires just the right combination of copper ions, temperature, light and Pfiesteria, explaining the difficulty researchers have had in reproducing the effect according to Moeller.
Although exotoxins like that produced by Pfiesteria are not common, the researchers observe, a number of other microalgae species are known to produce them, and under the right conditions in metal-rich waters they also might produce lethal variants... UNQUOTE.
SOURCE: http://www.sciencedaily.com/releases/2007/01/070119164427.htm |
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