Fly Fishing Forum - View Single Post - Dead zones in Gulf of Mexico continue to grow.
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Old 07-18-2007, 05:29 PM
popper popper is offline
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Join Date: Jul 2007
Location: Central New York
Posts: 19
I have an interesting side note to add to this, for people who follow this sort of stuff from a scientific angle. The report says that algae cause hypoxia when they decay. The reason is that bacteria which use oxygen break them down. However, the algae themselves can also cause dead zones in shallow bays. I've seen it happen. I've taken the measurements with an oxygen meter. Algae respire oxygen all of the time, just like we do. During the day, when they are photosynthesizing, on balance they give off more oxygen than they take in. But at night, or on dark days, they take in more oxygen than they give off. They can completely deplete a shallow water column of oxygen if the algae bloom is thick enough. I brought this up to my graduate advisor at the time that we were taking these measurements and he didn't really run with it because they were looking at something else. Anyway, you can get these kind of fish kills anywhere in the U.S. that there is a lot of fertilizer runoff into shallow bays. The water column does not need to be stratified. We used to see fish kills whenever it rained. The oxygen would go down to zero ppm at night, but it wouldn't rebound at day because of the low sunlight.

We are poisoning our waters with too much nitrogen and phosphorus in fertilizer. Plants like it just as much in the water as they do on land. That's why the water gets all green and soupy and dead eventually.
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