Published Date: 2011-10-26 09:42:45
Subject: PRO/AH/EDR> Red tide, fish - USA: (TX)
Archive Number: 20111026.3180
RED TIDE, FISH - USA: (TEXAS)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 24 Oct 2011
Source: Corpus Christi Caller Times [edited]
The most widespread bloom of toxic red algae to plague Texas in a
decade continues to kill fish and cause respiratory irritation along
Coastal Bend beaches and bayfronts.
Rust-colored water stretched from Matagorda Bay to South Padre Island
on Monday [24 Oct 2011], according to Meridith Byrd, a harmful algae
specialist with Texas Parks & Wildlife. Local reports include dead
fish and discolored water in Corpus Christi Bay near Ingleside by the
Bay, a fish kill at Goose Island State Park, and respiratory
discomfort and stressed fish in San Antonio Bay. There also are
reports of heavy aerosols along most Padre Island beaches with
moderate deposits of dead fish along parts of Mustang Island from Port
Aransas to just north of Packery Channel.
Biologists estimate this red tide outbreak has killed about 3 million
fish. The previous outbreak in 2009, which was confined to an area
from roughly Port Aransas to Mexico, killed an estimated 5.5 million
Beachgoers in Port Aransas last weekend [22-23 Oct 2011] endured heavy
aerosols, which cause itchy eyes, sore throats, and coughing, Byrd
said. The effects remained in the air there Monday, but were not as
strong. Dead fish along Mustang Island mostly were mullet, ladyfish,
and menhaden. The heaviest concentration of dead fish littered the
beach near the Fish Pass jetty.
Red algae thrive and multiply in warm salty seawater. Drought
conditions create saltier bays by limiting freshwater flow from rivers
and by not offsetting normal evaporation with rainfall. Generally, red
tide blooms subside when coastal waters cool.
A cool front is expected to hit the Coastal Bend this week [week of 24
Oct 2011]. Byrd said the gulf and bay temperatures must drop to about
60 deg F [15.5 deg C] to reverse the outbreak. Bay temperatures were
in the mid-70s [deg F/mid 20s deg C] Monday.
[Byline: David Sikes]
ProMED-mail from HealthMap alerts
[The areas mentioned can be located via the HealthMap/ProMED-mail
interactive map at http://healthmap.org/r/1mZZ. - Sr.Tech.Ed.MJ]
[The opening to this article talks about red algae. While there is red
algae, it is not what causes red tide. Red tide is much larger in
scope and can be toxic.
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 organisms.
Ocean spray containing the organisms 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
_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
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
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
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