This is not a road ...

FishKill-1.jpg

... It's an inlet filled with dead fish.

You're looking at a mass fish die-off. These don't happen every day, but they're also not particularly rare in southern Louisiana, where this photo was taken. The BP oil spill wasn't to blame for this die-off. Instead, it's the result of a very large number of fish getting trapped by the tide in a very shallow pool of water on a very hot day. All of those factors added up to not enough oxygen to go around, and the fish suffocated.

But unfortunate accidents of nature aren't the only reason fish drown in southern Louisiana. Last year on BoingBoing, I wrote about what happens when nitrogen and phosphorous-rich fertilizer runoff from Midwestern farms makes its way into the Gulf of Mexico:

Technically, Rabalais said, nitrogen and phosphorous are good things. Without them, you don't get life. In fact, a little extra nitrogen and phosphorous actually improve fishy existence, by plumping up the plankton population. Plankton feed on nutrients, fish feed on plankton and people serve the fish up in a nice butter sauce.

Those nutrients are also food for plants. In fact, that's a big part of why we get excess nitrogen and phosphorous in the water system to begin with, because both are used as fertilizer on American farms. For example, in 2007, American corn farmers used more than 5 million tons of nitrogenous fertilizer.

But, while corn may have big appetite for plant food, but it's about as efficient at "eating" as a toddler with a bowl of spaghetti. You know the kid will wear as much food as she eats. And a corn field will often use as little as half the fertilizer it's fed. The rest just sits on the soil until it's washed away into the nearest creek by rain or irrigation. Several river systems and thousands of miles away, the Mississippi Delta vomits out water saturated with the nitrogen runoff of every corn farm in the Midwest. In the Gulf of Mexico, the nitrogen becomes a buffet for another plant--algae--which, in the sort of natural cycle that completely fails to inspire Disney song writers, first cut off light needed by underwater plants and animals and eventually die off in numbers so large that their decomposition consumes every drop of available oxygen, suffocating aquatic life for miles around. It's the Circle of Death. And it doesn't make a great musical number.

Via New Scientist

Image: Plaquemines Parish Government

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