Red Tide Rolls in Early, Alarming Gulf Coast

Mar 13, 2023

Floridians and Texans are facing an unwelcome sight this month. Many of their white-sand beaches have been painted an all-too-familiar shade of scarlet. The crimson hue is the result of the early arrival of the so-called “red tide.” The red tide has caused many fish to die. People are complaining that it's bothering their breathing.

Red tides result when large blooms of the algae Karenia brevis are pushed to shore by upwelling. That's the tidal movement of nutrient-rich soil from the ocean floor to shallower areas. The algae feeds on those nutrients. It follows the food source toward land.

Normally, red tides occur in the fall. That's when summer-heated waters give rise to strong winds and hurricanes that force the algae northward. It generally goes away come winter, when northern winds push the blooms back out to sea. That didn’t happen this year, though.

“If we tend to get fewer northerly winds in the winter because of climate change, we will tend to see longer-lasting blooms,” Richard Stumpf, a scientist at NOAA, told The Washington Post. In other words, the warmer weather meant the algae stuck around all winter. Now, it's blooming. 

Karenia brevis is toxic. The chemicals it creates can harm both wildlife and humans. If breathed by a fish, the algae can paralyze its gills. As a result, it drowns. Those toxins stay in the fish even after death. So birds, turtles, and dolphins that eat them get poisoned. And as Karenia brevis washes ashore and dries, those chemicals can become airborne. They bother human lungs, noises, and eyes. 

Photo by courtesy of Unsplash.

Based on the details in the story, which paragraph of the article informs students about the harmful effects of the algae Karenia brevis on humans? (Common Core RI.5.5; RI.6.5)
a. two
b. three
c. four
d. five
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