MOBILE, Alabama - The dead zone in the Gulf of Mexico, which is an oxygen-depleted area devoid of sea-life, failed to grow large enough to reach Alabama waters this summer. But according to Sean Powers, a marine scientist and faculty member at the Dauphin Island Sea Lab, that’s not exactly good news.
“It’s definitely something we’re concerned about,” Powers said.
Caused by algae blooms fueled by nutrient-rich fertilizers pouring into the Mississippi River from the Midwest farm-belt, the dead zone was smaller than expected, but still twice the size of last year, spanning an area the size of Connecticut, according to the National Oceanic and Atmospheric Administration (NOAA).
The dead zone, which is typically concentrated west of the Mississippi Rivers, expanded into Alabama waters twice in the last six years.
According to Nancy Rabalais, director of the Louisiana Universities Marine Consortium (LUMCON) leading the NOAA survey, it’s only a matter of time before it comes back.
“It going to remain large unless there are concerted efforts to reduce nitrogen and phosphorus,” Rablais said. “It’s going to require some social and political willpower.”
Over the last two years, Sean Powers and researchers at the Dauphin Island Sea Lab have been conducting low-oxygen surveys off the coast of Alabama and Mississippi in conjunction with Rabalais' team.
This year, Powers said they didn’t find hypoxia, or low-oxygen areas, on a large scale.
“That’s not to say we don’t have low-oxygen water off Alabama, in fact we have it quite frequently,” he said.
In Mobile Bay, records of jubilees, an event where fish swarm into shallow waters due to low-oxygen, date back nearly 150 years.
These small pockets of oxygen-starved water occur more frequently with elevated levels of nitrogen and phosphorus, which are found in commercial fertilizers, according to Powers.
The nutrients stimulate an algae bloom that eventually sinks to the ocean floor and decomposes. The break-down of organic material encourages bacterial growth, consuming the oxygen needed to support life.
“We get hypoxia in our bays and estuaries, but sometimes there’s too much,” he said.
On a small scale, low-oxygenenated waters can cause jubilees and fish kills, which is what happened earlier this month when thousands of dead fish, stingrays, crabs and shrimp washed up on Mississippi beaches.
On a large scale, like in the instance of this year's dead zone, which spans 5,840 square miles of the Gulf floor, Powers said it can have irreparable damage on the fishing industry.
“Most fish are capable of getting out the system,” he said. “But it kills all the worms and clams that the fish need to grow on, so when they come back, there’s not much for them to eat.”
In order to stop the dead zone's growth, Power's said an immediate response is necessary, one that focuses on reducing fertilizer use and waste-water runoff.