Study Shows Pollution Harms Coral Reefs, But Action Can Help

A three-year study of more than 1,200 corals off the coast of Florida confirms the suspicion that pollution from nitrogen and phosphorus dumping, known as nutrient loading, harms the organisms, but researchers suggest that corals could recover if the pollution were to stop. 

"What's exciting about this research is the clear experimental evidence that stopping the pollution can lead to coral recovery," Rebecca Verga-Thurber, an assistant professor in the College of Science at Oregon State University, said in a statement. "A lot of people have been hoping for some news like this."

For years, scientists have watched as coral reefs have suffered in the face of increased levels of sewage or fertilizer runoff. Still, in the absence of controlled studies, they were unable to officially point a finger at the increased pollution. The new study is the first to examine the impact of nutrient loading in a controlled setting over a significant period of time.

From 2009-2012, researchers injected the corals, located in study plots near Key Largo, full of the nutrients and watched as disease doubled and coral bleaching, an indication of stress, more than tripled.

"We were shocked to see the rapid increase in disease and bleaching from a level of pollution that's fairly common in areas affected by sewage discharge, or fertilizers from agricultural or urban use," Verga-Thurber said.

"But what was even more surprising is that corals were able to make a strong recovery within 10 months after the nutrient enrichment was stopped," the researcher explained. "The problems disappeared."

Such results offer "real evidence" that, in addition to the problems nutrient overloading pose for corals, any actions taken to eliminate the pollution can be highly effective.

"This is actually very good news."

The study was published in the journal Global Change Biology.