Photo: NOAA public domain
The plankton species responsible for some types of the toxic “red tide” that washes up in coastal areas could be more dangerous than we thought. These toxins can enter the food supply and kill humans.New research into this plankton species, named Alexandrium tamarense, shows that it sends out multiple types of chemical weapons to kill its rivals. One of these toxins is deadly to larger organisms and the other is deadly to small organisms.
The study was published online in the journal Aquatic Microbial Ecology. Their findings could impact the entire marine food chain. “If it’s killing multicellular animals with one toxin and small protists with another, it could be the killer of the ocean world,” study researcher Hans Dam, from the University of Connecticut, said in a statement from the university.
Red tides are sometimes natural, but are also often caused by run off from populations centres near the coast, usually fertiliser run off from agriculture.
When A. tamarense blooms out of control, like during a red tide event, it could destroy the local marine food web — like it did in the Northeastern coast in 2005 near Cape Cod. When toxins from red tide make their way into the food web shellfish like lobsters, clams and even fish become toxic, too, causing human illness and death.
“This toxin blocks sodium channels in anything that has a well-developed nervous system,” Dam says. This can cause paralysis or even death. “But most of the organisms in the ocean are not those kinds of organisms. They’re single-celled, similar to the algae themselves, and they don’t have a well-developed nervous system.”
The new research found that these single-celled organisms were being attacked by a separate toxin from the plankton bloom — one that kills them directly. This would also have a large impact on the food web, since these small organisms are food for the larger ones.
“The amazing thing is, when you look at these algae under a microscope, they’re so beautiful — but they’re so deadly,” says Dam. “We call them the beautiful assassins.”
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