A Moment of Science

Red Tide

Researchers are still working to understand this serious natural phenomenon.

red_tide

Photo: AJ Cann

It's called red tide because it can look like a reddish brown sheen on the surface of the waves.

Red tide can occur in coastal ocean water around the world. It’s called red tide because it can look like a reddish brown sheen on the surface of the waves. Although it might look like pollution, it’s a natural phenomenon, caused by a sudden increase in the population of tiny, single-celled algae. This microscopic population explosion at the bottom of the food chain can be harmful to those at the top, because many of the algae responsible for red tide produce potent chemical toxins in their microscopic bodies.

In some regions, people can experience irritation of the eyes, nose, or throat when they are at the shore near a concentration of red tide, because wind, crashing surf, and even boat propellers can mix the toxic algae into the ocean spray.

The effects on marine life can be more serious, however. Oysters, clams, and shellfish eat by filtering algae out of the seawater, so they can concentrate the toxin in their bodies, making some of these animals unsafe for humans to eat. The toxins can also kill fish, which absorb these chemicals through their gills, and kill other marine animals that eat fish, such as dolphins.

Researchers are still working to understand this serious natural phenomenon.

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science