Published Date: 2011-12-16 10:26:19
Subject: PRO/AH/EDR> Red tide, shellfish - USA (02): (TX) oyster
Archive Number: 20111216.3608
RED TIDE, SHELLFISH - USA (02): (TEXAS) OYSTER
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Wed 14 Dec 2011
Source: The Florida Independent, USA Today report [edited]
A widespread toxic algae outbreak has shut down oyster season across
the Texas coast and caused health problems for many nearby residents.
Fueled by Texas' ongoing drought, the algae -- known as _Karenia
brevis_ -- [one of the causative agents for red tide. - Mod.TG] thrive
in warm, salty water and have spread through the bays and islands
along Texas' 350-mile coast [560 km], says Meridith Byrd, a marine
biologist for the Texas Parks and Wildlife Department. The algae could
cause nausea, vomiting, and diarrhea in humans and are harmful to fish
but not fatal to people, she says.
State health officials took the rare step of closing the entire coast
for oyster harvesting -- all 17 586 acres [7117 ha] of oyster beds --
before the season opened 1 Nov 2011. The state has shut down the
entire coast before, most recently in 2000, according to state health
officials. But the size of the current bloom coupled with the state's
ongoing drought and lack of rain could make it one of the biggest and
most destructive in history, Byrd says. The bloom so far has killed
4.5 million fish, she says.
In Florida, algae blooms have caused health problems for residents
and, in towns that rely on water to fuel their business, have hurt the
The Texas bloom appears different from those in Florida and is likely
caused by red tide that, due to the drought, is creeping ever-closer
to oyster beds near the shore.
A parasite known as "dermo", which has fast been spreading through
Texas coastal waters, is also becoming a major threat to the
And it isn't just the shellfish industry that's hurting. One hardware
store owner told USA Today that the closures are costing his business
at least USD 4000 a month. Restaurants, fueling stations, and fishing
equipment suppliers have also been negatively impacted.
The Texas bloom is only the latest in a string of events negatively
affecting the state's USD 30 million oyster industry. In 2005,
Hurricane Katrina devastated the Gulf Coast area, and remains the
costliest natural disaster the country has ever seen. Last year's
 gulf oil spill only made matters worse -- especially for the
fishing industry, which is still grappling with consumer's concerns
over the safety of Gulf of Mexico seafood.
[Byline: Virginia Chamlee]
ProMED-mail from HealthMap alerts
[This article is confusing.
Red tide is the name of a situation caused by one or more
dinoflagellates, of which _Karenia brevis_ is one of the more
prevalent organisms. _Karenia brevis_ has been known by other names:
_Ptychodiscus brevis_ and _Gymnodinium breve_. This organism, by any
of these names, produces brevetoxins and its derivatives.
Dinoflagellates are marine single-celled, photosynthetic organisms
that can "bloom".
Dermo is the common name for an oyster disease caused by the protozoan
parasite _Perkinsus marinus_, a single-celled organism that has many
different life stages. It thrives in water when the temperature is
between 25 and 30 deg C (77 and 86 deg F). Or, stated another way,
generally between May and October in the warm Gulf of Mexico waters.
While the organism is frequently found there, it can thrive in any
marine waters that meet its temperature requirements and have oysters
for it to infect.
Dermo infects the digestive system of the oyster causing a rather slow
death, over the course of 1 or 2 years. It impairs the oyster's
ability to feed, to reproduce, and to live.
So in reality, there may be 2 problems. Both problems have profound
impact on the oyster industry. However, red tide does not cause dermo
and dermo does not cause red tide. They are 2 separate events that
happen to affect oysters. - Mod.TG]
[Texas and the Gulf of Mexico can be seen on the HealthMap/ProMED-mail
interactive map at http://healthmap.org/r/1mfK. - Sr.Tech.Ed.MJ]