Red tide
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Image:La-Jolla-Red-Tide.780.jpg
Red tide is estuarine or marine algal bloom. Red tide is caused by species of dinoflagellates, often present in sufficient numbers (thousands or millions of cells per milliliter) to turn the water red or brown. The species responsible for red tides on the gulf coast of Florida is a dinoflagellate called Karenia brevis (formerly Gymnodinium breve.) It produces brevetoxins which produce respiratory irritation in humans.
Coastal water pollution produced by humans and systematic increase in sea water temperature appear to be causal factors in red tides. On the Pacific Coast of the U.S. there have been apparent increases in the occurrence of red tides since about 1991. these increases are correlated with a marine temperature rise of about one degree Celsius, and also with increased nutrient loading into ocean waters. As another example, algal blooms in lakes and rivers may be caused by greatly increased amounts of phosphorus or nitrogen entering an aquatic ecosystem from either sewage systems or surface runoff of agricultural fertilizers. Some red tides on the Pacific coast have also been linked to occurrences of El Nino events. Red tides also occur in places where there are no obvious associated human activities. Some red tides produce large quantities of toxins, such as saxitoxin, which disrupt the proper function of ion channels in neurons. Domoic acid, causative of neurological damage in certain marine mammals, is one toxin associated with red tides. The red tide toxins can induce neurological damage and death in marine mammals and can increase fish mortality; they are also accumulated by filter feeders. This bioaccumulation of toxins causes bivalves – like oysters and clams – collected in areas affected by algal blooms to be potentially dangerous for human consumption.
Gymnocin A is a cytotoxic polyether and a typical representative of toxins associated with red tide Template:Ref.
External links
- Harmful Algae and Red Tide Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
- Toxic Blooms: Understanding Red Tides, a seminar by the Woods Hole Oceanographic Institution
- Gulf of Mexico Dead Zone and Red Tides
- Red Tide updates for the Gulf Coast of Florida provided by Mote Marine Laboratory in Sarasota, FL
References
- Template:Note Ladder Polyether Synthesis via Epoxide-Opening Cascades Using a Disappearing Directing Group Graham L. Simpson, Timothy P. Heffron, Estíbaliz Merino, and Timothy F. Jamison J. Am. Chem. Soc.; 2006; 128(4) pp 1056 - 1057; (Communication) DOI: 10.1021/ja057973p Abstractzh:紅潮