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Oceans

Coastal ‘Dead Zones’ Are Multiplying. Seaweed May Be a Solution

Scientists say a massive expansion of aquaculture could slow the ecological and economic destruction wrought by agriculture and urban waste.

The Mississippi River empties into the Gulf of Mexico, carrying Midwest farm fertilizer and animal waste along with it.

The Mississippi River empties into the Gulf of Mexico, carrying Midwest farm fertilizer and animal waste along with it.

Photographer: Luke Sharrett/Bloomberg

In May 2019, the Mississippi River dumped a daily average of more than 5,000 metric tons of nitrate and 800 metric tons of phosphorous into the Gulf of Mexico, the highest levels in the last 40 years. These excess nutrients from Midwest farm fertilizer and animal waste rob the waters off Louisiana, Mississippi and Texas of oxygen, fueling toxic algal blooms and causing what’s come to be known as a dead zone.

The size varies each year, but this particular patch’s five-year average hovers at about 5,000 square miles. To date, a U.S. government task force has made little if any progress toward the goal of reducing it to 2,000 square miles.