Act locally, thinksoutherly
By Natalie Camplair, Twin Cities Daily Planet
18 August 2011
This time of year, 1,000 miles south of Minnesota at the mouth of the Mississippi River there are 7,000 square miles of the Gulf of Mexico devoid of any form of life. The swath of ocean where oxygen levels drop so low that fish and other marine animals are killed off is called the “dead zone.”
The appearance of the dead zone is a seasonal occurrence, fueled by water runoff from farms that contains nitrates and phosphorous. When these nutrients reach the Gulf of Mexico, they cause “algal blooms” (the same thing happens in Minnesota lakes and ponds in the summer). When the algae die, bacteria consume them, and in the process also consume the oxygen in the water that normally sustains fish, crabs, shrimp and mussels which live in the Gulf of Mexico. Researchers estimate that the shrimp habitat in the Gulf of Mexico suffers a loss of 25% due to the dead zone, directly harming the valuable shrimp industry there.