This month marks a full year that the noxious red tide, a harmful algae bloom that can kill fish and cause respiratory irritation in humans, has plagued the Florida coast. These algae blooms are nothing new for Florida, but the long duration of this one has some environmentalists pinning the blame on global warming and other human activities.

But other experts caution that red tides in Florida go as far back as the time of the Spanish explorers, long before human activity caused much impact. And the current bloom is not that unusually long, according to David Shormann, a marine chemist. Between 2004 and 2006 Florida experienced a bloom that lasted 17 months, and a 21-month bloom occurred a few years before that, he wrote in an op-ed for the Cornwall Alliance for the Stewardship of Creation.

A combination of interrelated processes causes algae blooms, Shormann explained. Tropical weather systems and trade winds carry iron-rich dust from the Sahara Desert that settles in the Gulf of Mexico in the late summer and early fall. The iron enables blue-green algae to flourish, and that algae converts nitrogen gas to nitrate. Karenia brevis, the red tide algae, needs nitrate, so Karenia blooms follow close on the heels of blue-green blooms. The toxins from Karenia kill certain kinds of fish whose decomposition releases more nutrients that allow the Karenia to continue blooming.

Also, Florida soil is naturally rich with phosphorous, another key nutrient for algae. When it rains, phosphorous from the soil makes its way to the coastal waters, feeding the blooms even further.

Fertilizers and sewage also contain nitrogen and phosphorous compounds, Shormann noted, and farmers should do everything they can to keep their soil and fertilizer out of the sea. But, he said, much of what causes red tides has nothing to do with human activity.

Kilauea U.S. Geological Survey/AP

Volcano threats

Eighteen volcanos in the United States pose a “very high threat” according to the newly updated U.S. Geological Survey. The experts ranked the volcanos on the potential severity of the damage an eruption would cause, not on which are most apt to blow.

Scientists ranked Hawaii’s recently erupting Kilauea, which is one of the most active volcanos in the country, as the most dangerous. Others in the Top 5 include: Mount St. Helens and Mount Rainier in Washington, Alaska’s Redoubt Volcano, and Mount Shasta in California.

Of the Top 5, Washington’s Mount Rainier “has the highest number of people in the downstream hazard zone,” about 300,000, Angie Diefenbach, a report co-author, said.

The rest of the 18 are: Mount Hood, Three Sisters, Newberry, and Crater Lake in Oregon; Akutan Island, Makushin, Mount Spurr, and Augustine in Alaska; Lassen and Long Valley in California; Mount Baker and Glacier Peak in Washington; and Mauna Loa in Hawaii. —J.B.

Microplastics Kyodo via AP Images

A microplastic problem?

Researchers in Austria last month found microplastics in human stool samples. Mainstream media quickly picked up the lament that microplastic pollution now invades our bodies.

But experts note the study, which involved only eight people, is too small to prove anything and no independent scientists reviewed it. Further, the authors didn’t explain what precautions they took to prevent sample contamination.

“In the worst case, all the plastic they found is from the lab,” Martin Wagner, a biologist at the Norwegian University of Science and Technology told The Associated Press. Also, finding microplatics in stool doesn’t mean they have entered the human body, he said. Microplastics, unlike food, are too large for our cells to absorb in the gut so they simply pass through. —J.B.