Ocean Dead Zones: Reducing Nitrogen Runoff Could Restore Vital Oxygen

Ocean Dead zones are low-oxygen areas that ultimately result from bacteria decomposing nitrogen-fueled algal blooms that have sunk to the ocean floor. As the bacteria feeds off the algae it depletes the ocean of vital oxygen. Creation of these zones is often attributed to fertilizers used for farming – speficially, the nitrogen that is a main component in fertilizers. Now, researchers from Brigham Young University (BYU) believe they have found a way to combat this contamination.

In their serach for a counter-measure to nitrigen-caused dead zones, researchers took a closer look at a naturally-occurring bacteria called rhizobia. This bacterium is vital to plants for use in processing nitrogen from the atmosphere. Basically, rhizobia turns nitrogen gas into a form that plants can consume, enabling them to grow.

Rhizobia-based fertilizers would enable farmers to use far less nitrogen based fertilizer – in turn, preventing fewer toxins from making it into oceans and reducing the dead zones and their impact on sealife. 

"If we can find better ways of getting nitrogen to plants, then we can improve the environmental impact of farming," Paul Price, lead author from BYU, said in a news release. "We want to improve this process so we don't have to add as much fertilizer to fields. With active rhizobia, we can have productive crops while still protecting the environment and keeping our waterways safer."

That's a little trickier than it sounds.

Rhizobia bacteria also contains a gene called HrrP that interacts negatively with plants, acting more like a parasite, destroying the plant instead of helping it.

"When this happens, the plant gets no benefit and the rhizobia behave more like a disease," Joel Griffitts, an associate professor of microbiology and molecular biology at BYU, said in a statement. "A single gene makes all the difference."

Understanding how to manipulate the HrrP gene could help researchers control how the bacteria affect plant functions; then researchers can develop rhizobia-based fertilizers that will help plants thrive without the problem of runoff creating damaging ocena dead zones.

The study was recently published in the journal Proceedings of the National Academy of Sciences.

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