New Study Uncovers Key Role of Bacteria in the Formation of ‘Red Tide’ Algal Blooms

Implications for Climate Modeling

November 16, 2009

Red tide.
Red tide.

High resolution (credit: NOAA )

According to a new study published in Proceedings of the National Academy of Sciences, NOAA and NOAA-funded university scientists are closer to understanding why “red tides,” called harmful algal blooms form. These toxic harmful algal blooms threaten marine ecosystems, human health, and cost local and regional economies millions of dollars annually through fishery closures and recreation and tourism losses.                                                                       

The study looked at the impact that the cooperative interactions between marine microalgae and bacteria have on the growth of harmful algal blooms

Scientists have long recognized that certain species of bacteria are closely associated with the microalgae that form the harmful algal blooms, but didn’t understand why the blooms formed or what role the bacteria play.

The researchers found that certain species of bacteria form a mutually-beneficial relationship with the algae that promotes the growth of each. The bacteria release a chemical which helps the algae absorb iron, a critical nutrient for photosynthesis. The algae, in turn, release organic compounds to support the growth of the bacteria.

The potential impacts of the study are extensive, and could result in improved modeling and forecasting of harmful algal blooms or potential strategies for prevention, according to William Sunda, Ph.D., of NOAA’s Beaufort Laboratory, a co-author of the report.

 “The results of the research have global implications,” said Sunda. “If we can find a way to inhibit the bacteria we should be able to help communities around the world deal with problematic and costly algal blooms.”

The study also offers new insight for climate change models, since dimethylsulfide, a gas produced by the bloom-forming algae, plays a critical role in the process of cloud formation and the ability of clouds to reflect sunlight back into space. The degree to which light is reflected in turn influences solar heating of the Earth, affecting global climate. 

NOAA understands and predicts changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.