Toxic Algae Destroys Shark Brains

[n2doc]

By Jennifer Viegas

Toxins produced by red tide events can alter shark brains, resulting in "hyperexcitability" and even death, according to a new study that will appear in the September issue of the journal Aquatic Toxicology.

The study is the first to document how brevetoxins, which are brain-changing compounds synthesized by some harmful algal blooms, affect a free-ranging marine species. In this case, researchers focused on lemon sharks, but they believe many other types of sharks could fall victim to the toxins.

"Sharks are exposed via consumption of brevetoxin-contaminated water and food, such as shellfish," co-author Niladri Basu explained to Discovery News, mentioning that the toxins can easily cross the shark's blood-brain barrier that otherwise protects the brain.

"Once inside the brain, brevetoxins bind very strongly to a protein that controls sodium flow," added Basu, an assistant professor of environmental health sciences at the University of Michigan School of Public Health. "By disrupting sodium flow in the brain, nerve cells will over-fire and cause hyperexcitability and ultimately result in death."

more

http://news.discovery.com/earth/shark-brains-algae-blooms.html

[arachadillo]

1. Toxic Algae and Ocean Animals

"Toxins produced by red tide events can alter shark brains, resulting in "hyperexcitability" and even death, according to a new study that will appear in the September issue of the journal Aquatic Toxicology.

The study is the first to document how brevetoxins, which are brain-changing compounds synthesized by some harmful algal blooms, affect a free-ranging marine species. In this case, researchers focused on lemon sharks, but they believe many other types of sharks could fall victim to the toxins."

Additional Info: http://www.ibrrc.org/pelican_domoic.html">Crisis off our coast
It's happened with predictable regularity, every spring since International Bird Rescue Research Center (IBRRC) opened its center in San Pedro in 2001. The staff at the center, which specializes in seabirds, and especially California brown pelicans, calls it DA; short for Domoic Acid. The staff braces for the dead and dying birds they know will come, every spring.


Additional Info: http://shutterbug.ucsc.edu/sealion/view_album.php?set_albumName=album112">Sea Lion Gallery
The single most important toxic cause of illness and mortality in sea lions is DOMOIC ACID POISONING. Domoic acid is a natural substance (a BIOTOXIN) that is produced by a group of marine diatoms, organisms that make up a key part of the PLANKTON upon which the marine food web is based. The diatoms that produce domoic acid, or "DA" are in the genus PSEUDONITZSCHIA.

Additional Info http://www.nmfs.noaa.gov/pr/pdfs/health/bottlenose_brevetoxins.pdf">Bottlenose Dolphins and Brevetoxins

One hundred and seven bottlenose dolphins stranded dead on the coast of the Florida Panhandle between March 10 and April 13, 2004 (Flewelling et al., 2005; NOAA, 2004). During this UME, hundreds of dead marine fish and invertebrates also were discovered in the area. Although no bloom was evident in the area concurrent with the mortalities, epidemiological evidence strongly suggests that naturally occurring brevetoxins produced by the dinoflagellate Karenia brevis (formerly Gymnodinium breve and Ptychodiscus brevis) were responsible. Brevetoxin involvement has been implicated in other marine mammal mortality events in the region (Figure 1), including a mortality event that killed 152 bottlenose dolphins in the Florida Panhandle from August 1999 to May 2000 (NOAA, 2004; Mase et al., 2000) and a 1996 bottlenose dolphin mortality event in Mississippi (NOAA, 2004) that coincided with dense blooms of K. brevis.