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Fish killed by red tide in Sanibel, Fla. (Joe Raedle/Getty Images)

Science

Year-long tide

Algae bloom off Florida coast has many more-than-human causes 

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.

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Jack Guez/AFP/Getty Images

(Jack Guez/AFP/Getty Images)

Science

Abuzz over glyphosate

A weed killer’s effect on microbes may be linked to bee deaths 

Scientists say honey bee populations continue a serious, mysterious decline around the world, and that’s a problem for the agriculture industry, which relies on bees for pollination. Now a study suggests that glyphosate, the world’s most widely used weed killer, may be harming the insects.

According to the study, published Sept. 24 in the Proceedings of the National Academy of Sciences, glyphosate disrupts microbes in the bees’ digestive system, making them vulnerable to deadly infections. Previously, researchers did not consider the chemical a threat to insects and animals because it targets a cellular pathway that only plants and some bacteria possess.

In the PNAS study, researchers gave hundreds of bees a syrup containing glyphosate doses that mimicked the environmental levels bees would encounter if foraging among flowering weeds. They then compared those bees to another group of bees that received syrup without glyphosate.

After three days, the scientists found significantly lower levels of S. alvi, a bacterium that appears to protect bees from dangerous infections, in the bees that received glyphosate. Only 12 percent of the bees that ingested the chemical survived an infection caused by a bacterium commonly found in trace amounts in beehives. By comparison, 47 percent of the glyphosate-free bees survived the infection.

What about glyphosate and human microbiomes? According to Science magazine, humans likely encounter only very low exposure to glyphosate, and their guts harbor different microbes than bees’.


 

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Noah Berger/AP

(Noah Berger/AP)

Science

California carbon ban?

Lawmakers aim to wean the state’s electric grid off of fossil fuels

California lawmakers voted this summer for strict energy legislation that would require the state’s electricity sources to be 100 percent carbon-free within less than 30 years. The bill, passed by the State Senate and Assembly and signed by Gov. Jerry Brown on Sept. 10, will bump up California’s current mandate, increasing from 50 percent to 60 percent the amount of renewable power generation required in the state by 2030. The ultimate goal: All California electricity would be produced without greenhouse gases by 2045.

Under the law, California will eventually need to get all of its electric energy from sources such as wind, solar, geothermal, and dams. Lawmakers claim they will hash out the specifics later.

Supporters hope the plan will influence the rest of the nation. “We have to show what can be done,” Assemblyman Bill Quirk, a Democrat from Hayward, said in a statement. “If we can get to 100 percent renewables, others will as well.” (So far, only Hawaii has a similar mandate.)

Opponents of the bill, though, warned the goal is unachievable and could sharply increase the cost of energy for businesses, factories, and food processors—costs they will ultimately pass on to consumers. Assemblyman Jim Patterson, a Republican from Fresno, described the bill as “a leap of faith and a gamble,” the Los Angeles Times reported.

The measure elicited the most opposition from Republican lawmakers, but some Democrats voted against it as well. Democratic Assemblyman Adam Gray accused the plan’s proponents of trying to impress progressives across the country rather than considering the poor residents of rural communities who would face higher electricity bills. “This is yet another in a laundry list of bills that are discriminatory to the people I represent,” he said.

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