Toxins released during certain red tide events can overexcite sharks, sometimes leading to death.
Scientists have documted how certain algal bloom toxins affect a free-ranging marine species.
Humans may be partly to blame, since agricultural run-off can lead to the formation and growth of red tides.
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.