One benefit of the midwest drought

From Texas A&M University

Good news from the bad drought: Gulf ‘Dead Zone’ smallest in years, says Texas A&M expert

The worst drought to hit the United States in at least 50 years does have one benefit: it has created the smallest “dead zone” in the Gulf of Mexico in years, says a Texas A&M University researcher who has just returned from gulf waters.

Oceanography professor Steve DiMarco, one of the world’s leading authorities on the dead zone, says he and other Texas A&M researchers and graduate students analyzed the Gulf Aug. 15-21 and covered more than 1,200 miles of cruise track, from Texas to Louisiana. The team found no hypoxia off the Texas coast while only finding hypoxia near the Mississippi River delta on the Louisiana coast.

“We had to really hunt to find any hypoxia at all and Texas had none,” he explains.

“The most severe hypoxia levels were found near Terrabonne Bay and Barataria Bay off the coast of southeast Louisiana.

“In all, we found about 1,580 square miles of hypoxia compared to about 3,400 square miles in August 2011. What has happened is that the drought has caused very little fresh-water runoff and nutrient load into the Gulf, and that means a smaller region for marine life to be impacted.”

DiMarco has made 27 research trips to investigate the dead zone since 2003.

DiMarco says the size of the dead zone off coastal Louisiana has been routinely monitored for about 25 years. Previous research has also shown that nitrogen levels in the Gulf related to human activities have tripled over the past 50 years. During the past five years, the dead zone has averaged about 5,700 square miles and has reached as high as 9,400 square miles.

Hypoxia is when oxygen levels in seawater drop to dangerously low levels, defined as concentrations less than 2 milligrams per liter, and persistent hypoxia can potentially result in fish kills and harm marine life, thereby creating a “dead zone” of life in that particular area.

The Mississippi is the largest river in the United States, draining 40 percent of the land area of the country. It also accounts for almost 90 percent of the freshwater runoff into the Gulf of Mexico.

“These findings confirm what we found in a trip to the Gulf back in June, and also what other researchers in Louisiana have discovered, so there is general agreement that the dead zone this year is a very, very small one.

“But the situation could certainly change by next spring,” DiMarco adds.

“The changes we see year to year are extreme. For example, last year, record flooding of the Mississippi River and westerly winds in the Gulf led to a much larger hypoxic area, particularly earlier in the summer. We’ll just have to wait and see what kind of rainfall is in store for the Midwest over the next 8-10 months.”

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Participating at sea with DiMarco were Piers Chapman and Matthew Howard of the Department of Oceanography, Chris Shank of the University of Texas Marine Science Institute, TAMU graduate students: Ruth Mullins Perry, Emma Cochran, Laura Harred, Allyson Burgess Lucchese (Texas A&M-Galveston), and Marine Technicians Andrew Dancer and Eddie Webb and Alex and Tyler Mifflin of the Canadian TV show the Water Brothers.

On-shore participants included Lisa Campbell, Wilf Gardner and Mary Jo Richardson (oceanography), Antonietta Quigg (Texas A&M-Galveston) and Ethan Grossman (geology and geophysics).

The project was funded by NOAA’s Center for Sponsored Coastal Ocean Research.

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28 thoughts on “One benefit of the midwest drought

  1. Is a marine ‘Dead Zone’ influencing CO2 levels? Probably not because the area is still too small compared to the rest of the ocean. But I have always wondered if the increasing use of fertilizers during the 20th century effected global CO2 levels in any way.

  2. During the past five years, the dead zone has averaged about 5,700 square miles

    That is such typical presentation of numbers out of context to look impressive. Actually 5700 square miles is less than 1% of the area of the 5.79E5 mi^2 Gulf of Mexico (and the former is tens of thousands of times less than total ocean area). Even though unintentional runoff is wrongly distributed and not the ideal mix of nutrients, I wouldn’t be surprised if likely the net overall effect of the fertilizer runoff outside the overconcentrated zone may be extra marine life feeding on an increase in the photosynthetic basis of the marine food chain (but fat chance of such ever being mentioned if so).

  3. Isaac’s rainfall into the Mississippi watershed will “fix” both…and then New Orleans will get to deal with the residues…

  4. Remember last year when they claimed that sea level rise had fallen because of all that rain that had fallen on the land? Well presumably it has all run off now. In fact, that’s what this study says is the reason for the fall in hypoxia. Therefore sea levels should have recovered all of last year’s precitpitation loss on land (and more because sea levels rise ever upward bevasue of global warming) and we can expect a sudden lurch in the sea level graph . . .

  5. I have an easy time finding dead zones in the gulf. Every time I go fishing, I don’t catch anything. (rimshot) Couldn’t be the fisherman, could it?
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    This is pretty straightforward stuff. DiMarco is building a nice little database, although the number of extras on the team seems excessive to me; 15 others besides DiMarco?

    I wonder if the data quality would be better or worse if someone just stayed ashore and polled fishing boats as they came in?

  6. Was there a dead zone prior to the widespread use of fertilizers? From what – admittedly little – I’ve read about hypoxia (i.e. oxygen depletion) in the ocean it sounds like it occurs naturally and would be expected to be seen occurring at the Mississippi outlet to some extent without human factors being involved.

    Just so I’m clear, this is not to say that this is all a natural phenomenon. What I am asking is to what extent if any, is that x-thousand miles most likely man-made vs. natural?

  7. Although the gulf has obviously not completely recovered from the Deepwater Horizon oil spill, it’s nice to hear this just 2 years later.

  8. Wait a minute. The hypoxia is related to river influx into the Gulf. So every thing in the rivers is dead? And as the rivers dissipate their hypoxic condition into the ocean, the dead zone becomes concentrated. Yes I’m confused.

  9. “Hypoxia is when oxygen levels in seawater drop to dangerously low levels, defined as concentrations less than 2 milligrams per liter, and persistent hypoxia can potentially result in fish kills and harm marine life, thereby creating a “dead zone” of life in that particular area.”

    Uh no. A “dead zone” would be where things are dead, not where there is potential for things dying if the conditions is “persistent”. Which it obviously is not since they have to search all over the place from year to year to find these elusive zones. The research may be legitimate but the hype is not. If there were really dead zones there would be iconic polar bearesque photos of the dead fish all over the Internet and the covers of the IPCC reports. They have defined a naturally occurring seawater condition, labeled it by their own worst case scenario terms, filled out the paper work and collected their grants. How about “transient idiopathic areas of high nutrients” or “super growth zones”. No… “dead zones” is better for grant seeking.

  10. This is an interesting conundrum: the fertilizer levels in the Mississippi water aren’t enough to stunt (at all!) freshwater aquatic life, and obviously whatever is in the Mississippi water becomes diluted by seawater when it hits the ocean, yet it produces such a growth of phytoplancton in the Gulf even diluted that a hypoxia-inducing amount of microbial degradation activity occurs on the sea bottom because of the overwhelming amount of dead plankton that falls to the bottom. So the problem isn’t in the Mississippi ecosystem, it is in the Gulf, but not the type the eco-green understand.

    Is not the “problem” that we are dealing with the LACK of phosphates (and iron, problably) in the Gulf waters generally, that the Gulf is a relative desert in the opinions of shallower dwelling organisms, AND that the hypoxic zone has insufficient bottom-water circulation?

    It sounds to me that during high biotic actitivity in the Gulf there is a natural hypoxic sub-basin due to bottom current patterns. The way to get rid of the hypoxic zone is to reduce biotic activity in the Gulf. In other words, fix the bottom by detroying the top. Let deep skates live by starving the shallow snappers. The reason the Gulf waters are so clear, like those of Hawaii, as we know, is that there is nothing growing in it – the reason whales don’t feed during the breeding time in Hawaii (not ’cause pregnant whales aren’t hungry).

    Man and the Mississippi are doint the Gulf biosphere a favour. All that phytoplankton is manna from land as far as the fish are concerned. There is no hypoxia in the shallow column, but lots of plankton. Yum, yum, yum.

    But this is an eco-problem.

    Hey: isn’t this similar to Strong et al, who say only the rich, white First World should live well in a “natural” world, and we can best get back to a natural state by getting rid of the several billion poor, brown Third Worlders?

    Food and energy: keep it for the fish and guys we like.

  11. For those confused its a very simple circle of life process ( and a very natural occurence), we have a very similar problem in the Chesapeake Bay. Heavier rainfall causes larger amounts of nitrogen from naturally occuring sources, human introduced fertilizer and livestock manure to get into the streams and rivers which once it gets to a more stagnant area of water – increases algae blooms and underwater plant growth. As the plant material decays – it depletes oxygen in the water and makes dead zones where fish, crabs etc. cannot breathe.

  12. @ NickB. says:
    August 27, 2012 at 6:57 am

    Was there a dead zone prior to the widespread use of fertilizers? From what – admittedly little – I’ve read about hypoxia (i.e. oxygen depletion) in the ocean it sounds like it occurs naturally and would be expected to be seen occurring at the Mississippi outlet to some extent without human factors being involved.

    Just so I’m clear, this is not to say that this is all a natural phenomenon. What I am asking is to what extent if any, is that x-thousand miles most likely man-made vs. natural?

    ***********************************************************

    The Big Muddy and the rivers that drain into it from the Great Plains between the Rockies and the Appalachians have been doing this since the last ice age. Recall the millions of bison that roamed the plains and the millions of tons of bison and other animal poop that was washed into the Gulf over thousands of years. I’d say any human contribution in the last hundred years or so would be so small as to be invisible compared to that.

  13. Sorry, but I am going to have to say there is some human impact to dead zones. More importantly, maybe we should stop spending money on false AGW science and apply it to real problems like this. Of note, large dead zones could be a problem made worse due to the low amount of hurricane activity.

  14. .RE: @ NickB. says:
    August 27, 2012 at 6:57 am

    “….What I am asking is to what extent if any, is that x-thousand miles most likely man-made vs. natural?”

    Important question. Hypoxia is influenced by the amount of fresh water, which creates the “lid,” and the amount of nutrients. The fresh water on top of the saltier water keeps the lower water from mixing with the upper, whereupon the critters in the lower water use up all the oxygen and die. It is assumed that extra fertilizer from upstream makes them grow more and use up the oxygen faster.

    However, if the upper water does not mix with the lower, how does the fertilizer get down below without the dissolved oxygen getting down below.

    Also the amount of dirt, which is pretty nutritious stuff, has been reduced. I recently heard the Mississippi used to dump 406 million tons at the delta, but now it is only 145 million.

    Lastly, even if there was not a man alive, the amount that the Mississippi’s flow can vary from year to year is huge. A Dust Bowl year would be totally different, both in terms of fresh water and in terms of dissolved nutrients, from a year with widespread flooding. The swings in natural hypoxia would be enormous. Then you add in a hurricane like Isaac. If Isaac truly winds up, the surface of the gulf is “oxygenated” by towering waves and winds that shred the sea to spray hundreds of feet high, and ten to twenty inches of rain are dumped onto the delta and up the Mississippi Valley.

    Anyone who thinks nature is “balanced,” and it is only man who “unbalances” it, ought head down to the delta today, and stay through Thursday.

  15. I bet it’s the UFI (Urban Fertilizer Island) effect. Lot’s of storm water coming off all that pavement.

    /no sarc>

  16. Nitrate is used by some sea micro-organisms as an electron accepter, so reduced run off of agricultural nitrates would limit their proliferation & thus allay their cumulative using up of the locally dissolved oxygen. Louisiana’s Terrabonne Bay and Barataria Bay are south/SW of New Orlean’s low lying lands fed by Mississippi River so apparently still receiving more agricultural nitrates than rest of 1,200 miles coastline surveyed & relatively showing less dissolved oxygen (ie: more hypoxia). Texas coast just isn’t draining water into the Gulf of Mexico the same as Louisiana.

    There are other factors, in other sea environments, with relationships to changes in hypoxic conditions than is the case in coastal Gulf of Mexico dynamic. For example at coast of Southern California hypoxia is exasperated by early La Nina events (http://www.agu.org/pubs/crossref/2011/2011GL049549.shtml).

  17. The Gulf of Mexico just needs large scale bubblers to increase the oxygen levels much as Cardiff Bay has managed oxygen levels.

    I bet you that nobody has even calculated the cost/benefit ratio of extra fishing grounds vs cost of oxygenation. Wouldn’t it be a hoot if the local fisherman would gain so much that it would make sense to pass the hat and do it as a free market based improvement to the fisheries?

  18. “Oceanography professor Steve DiMarco, one of the world’s leading authorities on the dead zone,”

    How many authorities are there in the world? Are they studying this in Japan? Just sayin,’ no need for ‘world’s leading,’ ‘An authority’ would do.

  19. TMLutas says (August 27, 2012 at 10:54 am): “The Gulf of Mexico just needs large scale bubblers to increase the oxygen levels much as Cardiff Bay has managed oxygen levels.”

    Thanks for the reference to Cardiff Bay. I was wondering if bubble aeration had been tried anywhere; apparently it has.

    Wiki has a short article on pond/bay aeration:

    http://en.wikipedia.org/wiki/Water_aeration

    I doubt it would be practical for something the size of the Gulf, or even for the Gulf’s smaller but shifting “dead zones”.

  20. Hi Caleb,
    The peninsula south of New Orleans creates water pressure higher windward than those 2 studied bays to it’s west. This pressure gradient’s inertia (force in motion) interacts with the comparatively less forceful friction drag of the water movement along the coastal topography outside of those bays to create eddies. If there are any underwater elevated landforms outside those 2 bays then these will also engender eddies leeward from those underwater landforms.
    Eddies bring nutrients up from the sea bottom. It is a dynamic since as an eddy starts to form the upper isopycnal (water of same density water) shows upwelling, while deeper isopyncals drive down. Yet later on, as that eddy looses form the isopycnal stratification somewhat evens out.
    In general the Gulf of Mexico waters flow is toward the Yucatan on the west. When wind flow goes with the direction of water current there is up-welling (conversely wind contrary to ocean current provokes down-welling).

  21. Hi Mark B.,
    Dead zone is genuine science. Ocean hypoxia allows sulfides up-welling in sediments from anoxic layer of sea bottom. The depth of diffused oxygen penetration into the local sea bottom determines how thoroughly bottom micro-organisms naturally can oxidize enough of the up-welling sulfides into benign thio-sulfate.
    Hypoxia lets sulfides reach marine life forms where it can stymie the cytochrome c oxidase enzymatic action. It (sulfide) also cause problems due to proclivity for binding bind to cytochrome aa3 heme’s ferric iron. Different lifeforms show different levels of sulfide toxicity. Up-welled sulfides don’t always cause dead zones on the surface because some intermediate sea strata chemo-lithotrophs can “consume” sulfide.

  22. Logically, edges of ‘dead zones’ would suffer from extra yummy phyto’s. Do fish hover there, piggin’ out?

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