"Dead Zone" in the Gulf of Mehico

[Oldschooler]

http://rense.com/general56/deadzone.htm

For those who can handle depressing news...

~Roberto

[fishdoc11]

Good to know. Kinda dwarfs the red tide kills. And someone wants to repeal the clean water act. Sad, sad ,sad.
Chris

[PhoenixINX]

Interesting though... as it's only temporary during the summer.

The condition resides as the weather cools and farmers, etc stop using those chemicals.

[Oldschooler]

I guess what I find so interesting is the fact that the main cause are "nitrates". Sounds so familiar. Makes me laugh to think of how many people come into the shop each day and want to buy something they can just "put in the water" of their aquarium to "clean it". LOL "Yep. Here ya go, lady. Just what you NEED. *hands her a bottle off the shelf* This stuff here'll just make dirt and nitrates 'go away'. You'll NEVER have to change your water again!!!"

Seriously. People ask for "it". As if, if it EXISTED (which blows my mind that people think it DOES) we couldn't just go buy 55-gallon drums of the stuff and dump it in the oceans! Jeez, people...

~Roberto

[fishdoc11]

Fertilzers are major causes of polution. I remember during my environmental days there were several Superfund(read majorly poluted) sites that were golf courses. Funny you could be standing in the middle of a beutifull golf course and be surrounded by serious problems. I always cringe when I fish next to a guys yard that has perfect green grass with no weeds just thinking about the fertilizer and herbicide that flows out of the yard when it rains.
Chris

[coralreefing]

Alright, correct me if I'm wrong but their nitrate / algae theory seems backward. The article says "The nitrates, carried into the gulf's warm summer waters by the river, feed algae blooms that use up oxygen and make the water uninhabitable." But algae is photosynthetic so it should use up carbon dioxide & produce oxygen.

[kevlouie]

It goes both ways. It does what you described at night (I believe) but in the daytime it uses O2, therefore when the days are longer (summer) the problem gets worse, ie carp gulping air in an algae filled pond.

[coralreefing]

Isn't pond aeration more of a temp. issue. A pond requires more circulation for aeration in higher temps because warm water doesn't hold O2 as well as cool water. I don't think algae is a factor there. I may be all wet on this one but it just doesn't sound right to me.

[kevlouie]

Actually, I had it backwards

http://www.simplydiscus.com/library/biology/anatomy/o2_depletion.shtml

[EvilMel]

Ok so this is the subject that my lab works on at UT.

In Canada, Lake Erie specifially, they had a HUGE problem with eutrophication (loss of oxygen and death of everything basically). This was due to fertilizers running off into the lake and the release of phosphates into the water. The government put strict regulations on the amounts and types of fertilizers (and probably much more) that could be used, so the problems have decreased somewhat. There have been different problems of course, but this has helped greatly.

What happens in the area you guys are talking about is actually eutrophication as well. So the way it works (I believe) is that phytoplankton grow to a huge abundance (because the nutrient, seemingly nitrate in this case, that was limiting their growth is now present in large amounts) and they produce dissolved organic matter. When the phytoplankton produce tons of DOM, the bacteria that are present are able to grow to a HUGE abundance, depleting the water column of oxygen as they use it for their metabolism (respiration). In addition, phytoplankton growing to large abundances can cause there to be much less light penetration and so it can choke out aquatic plants/corals that need light to survive, producing even more organic matter for the bacteria to eat (as dead tissue).

Anyways that is my impression of what is occurring. It may not be totally accurate but then I did study similar issues for the past 6 years, so hopefully it will be fairly correct.

[coralreefing]

Thanks Mel
That makes much more sense than algae actually consuming oxygen.

[EvilMel]

No problem!