(From Blue Legacy's Expedition: Blue Planet)

Wilma Subra, southern Louisiana’s own activist-grandmother extraordinaire, was one of the first people to identify the Dead Zone. A chemist, she’d been conducting tests off of oil rigs in the Gulf of Mexico when she noticed a strange dearth of dissolved oxygen. She and other scientists launched an investigation, and now understand how the Dead Zone works.

Wilma explains, “Nitrogen and phosphorous from fertilizers travel down the Mississippi River and into the Gulf of Mexico. This makes algae blossom like crazy. As the algae grow, they use up all the oxygen. When they die off, they sink to the bottom of the ocean and use up more oxygen there, too. So there’s this layer of water in the Gulf that is void of oxygen—that means nothing can live there."  READ MORE

--from Alexandra Cousteau's Mississippi River blog/Expedition: Blue Planet

Alexandra Cousteau on a dock over the Mississippi River
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More from the Mississippi River Expedition on MNN:

Blue Legacy - St. Louis: Upstream America

Blue Legacy - How farmers may hurt the fishermen

Blue Legacy - Louisiana: Life on the edge

Blue Legacy - An interview with Louisiana musician Tab Benoit


Expedition: Blue Planet is part of Alexandra Cousteau's Blue Legacy. It is a 100-day journey across 5 continents exploring the most critical water issues of our time. This Expedition is not just about oceans: it's about people, our connection to water issues around the world, and a recognition that we all have the power to protect and replenish our most important life support system.

Expedition: Blue Planet

Blue Legacy - Louisiana: Downstream dead zone
Local young people are leaving the wetlands for jobs in cities partly because the Dead Zone is eradicating the Gulf of Mexico’s shrimp supplies.