Maine (Global Adventures): Scientists warn that a significant regional bloom of a toxic algae that can cause ‘red tides’ in the spring and summer of this year is possible, potentially threatening the New England shellfish industry. A survey conducted in late 2009 in the Gulf of Maine did show the highest amount of cysts ever measured, more than 60 percent higher than what was observed prior to the historic red tide of 2005.

The 2010 bloom could be similar to the major red tides of 2005 and 2008, according to Woods Hole Oceanographic Institution (WHOI) biologist Don Anderson, principal investigator of the Gulf of Maine Toxicity (GOMTOX) project.

While the algae pose no direct threat to humans, the toxins they produce can accumulate in filter-feeding organisms such as mussels and clams, which can cause paralytic shellfish poisoning (PSP) in humans who consume them.

Red tides are the result of algal bloom events involving toxic or otherwise harmful phytoplankton such the dinoflagellate Alexandrium fundyense, an organism that produces saxitoxin, the neurotoxin responsible for paralytic shellfish poisoning. Since such blooms often take on a red or brown hue, they are called "red tides". Out of the 5000 plus species of marine phytoplankton known today, only about 2 percent are harmful or toxic.

Examples of common harmful effects of toxic algae include:

• the production of neurotoxins which cause mass mortalities in fish, seabirds and marine mammals;
• human illness or death via consumption of seafood contaminated by toxic algae;
• mechanical damage to other organisms, such as disruption of epithelial gill tissues in fish, resulting in asphyxiation;
• oxygen depletion of the water column (hypoxia or anoxia) from cellular respiration and bacterial degradation.

It is not fully understood what causes harmful algae blooms. In some locations, they appear to be entirely natural, while in other locations they seem to be a result of human activity. Ammonia, urea, and nitrates, commonly used in fertilizers, can propagate algae blooms.

California coastal waters also experience seasonal blooms of Pseudo-nitzschia, a diatom known to produce a neurotoxin responsible for amnesic shellfish poisoning. The "Florida red tide" occurs in the Gulf of Mexico and is caused by and algae called Karenia brevis, another dinoflagellate which produces a neurotoxin responsible for neurotoxic shellfish poisoning.

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