RED TIDE, SHELLFISH - USA: (MASSACHUSETTS) ALERT
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Date: Wed 4 May 2011
Source: Cape Cod Times [edited]
<http://www.capecodonline.com/apps/pbcs.dll/article?AID=/20110504/NEWS11/110509903/-1/news>
The [Massachusetts] state Department of Public Health is urging consumers to throw away any shellfish harvested and sold after 29 Apr
2011 from the southern sections of the Nauset Marsh estuary due to a local red tide outbreak. This includes waters on the border of Eastham and Orleans [eastern or outer Cape Cod, Massachusetts].
The estuary has had red tide outbreaks for 26 of the past 35 years.
Shellfishermen have been banned from harvesting shellfish, sometimes for months in the spring and summer, because the red tide algae produce toxins that become concentrated in shellfish meat when they eat the free-floating algae.
According to a map released by the department, the tide closure is mostly in Orleans' waters. It covers the southern portion of the Nauset estuary, mostly south and west of Nauset Inlet, including Nauset Harbor, Mill Pond, Roberts, Woods and Rachel's coves, and the waters connecting them as well as all of Town Cove.
Only portions of Nauset Estuary south of Fort Hill Area are closed in Eastham. The northern waters including Salt Pond Bay, Nauset Bay, the various channels, and Salt Pond remain open.
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[Red tide is caused by several toxic algae. Depending upon the toxin, it is also known as paralytic shellfish poisoning (PSP), because it causes shellfish to be toxic for consumption.
_Alexandrium_ spp. is one of many members of this genus. Some members may not be toxic. However, generally, the genus is found in coastal waters high in nitrogen content. These organisms produce a neurotoxin, like many of the organisms capable of causing paralytic shellfish poisoning (PSP). The neurotoxin is considered fatal for humans consuming contaminated shellfish and may be dangerous to humans and animals who swim in waters that are 'blooming' with the organism.
Ocean spray containing the organism may also cause illnesses, including rashes and eye irritation in people. Some species of this genus are capable of causing 'red tide' that may be visible for long distances along a coast line.
PSP is a significant problem in several geographic areas, especially on both the east and west coasts of the US. Produced by several closely related species in the genus _Alexandrium_, PSP toxins are responsible for persistent problems due to their accumulation in filter-feeding shellfish, but they also move through the food chain, affecting zooplankton, fish larvae, adult fish, and even birds and marine mammals.
_Alexandrium_ blooms generally do not involve large-cell accumulations that discolor the water and may instead be invisible below the water surface. Low-density populations can cause severe problems due to the high potency of the toxins produced. Furthermore, _Alexandrium_ spp. can grow in relatively pristine waters, and it is difficult to argue that anthropogenic nutrient inputs are stimulating the blooms. These characteristics are important when considering mitigation and control strategies.
Often PSP is associated with red tides or algal blooms. Red tide is caused by an organism called _Karenia brevis_, which in high concentration can make the water look red. The organism releases a toxin that paralyzes the respiratory system of fish and other marine life.
Airborne toxins, water spray, and splashes in an outbreak have kept people from beaches while leaving others with irritated eyes and throats. Red tide irritates the skin of people exposed to it and can cause itchy eyes, scratchy throats, and coughs. Harvesting from affected areas for personal consumption is discouraged. Red tide poisoning symptoms include nausea and dizziness and may last for several days.
Previously the organism causing red tide was known as _Gymnodinium breve_, but it has been reclassified in the taxonomy of dinoflagellates. Its new name is _Karenia brevis_, or _K. brevis_.
Karenia was chosen in honor of Dr Karen Steidinger, a prominent red tide scientist from the Florida Marine Research Institute in St Petersburg, FL (<http://www.mote.org/index.php?src=gendocs&ref=%28renamed%29%20Red%20Tide%20Update_608&category=Ecotoxicology>).
- Mod.TG]
[The HealthMap/ProMED-mail interactive map of Massachusetts in the northeastern US can be seen at <http://healthmap.org/r/0OFi>. - Sr.Tech.Ed.MJ]
[see also:
2010
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Paralytic shellfish poisoning - USA: (ME) warning 20100714.2353
2007
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Paralytic shellfish poisoning, human - USA (ME) 20070802.2508 Red tide, aquatic mammals - USA: (FL) 20071231.4199 Manatee deaths, red tide - USA (FL) 20070403.1129
2006
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Red tide, shellfish - USA (WA) 20060824.2388
2005
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Red tide - USA (TX) 20051002.2886
Red tide - USA (FL) (06) 20050925.2829
Red tide- USA (FL) (05): sea turtles 20050819.2437] .................................................sb/tg/mj.lm/ll
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