Posted on 01/20/2009 12:43:08 PM PST by decimon
Considered pollutants in the West, discharges help to feed millions in Egypt
NARRAGANSETT, R.I. – January 19, 2009 – While many of the world's fisheries are in serious decline, the coastal Mediterranean fishery off the Nile Delta has expanded dramatically since the 1980s.
The surprising cause of this expansion, which followed a collapse of the fishery after completion of the Aswan High Dam in 1965, is run-off of fertilizers and sewage discharges in the region, according to a researcher at the University of Rhode Island Graduate School of Oceanography.
Autumn Oczkowski, a URI doctoral student, used stable isotopes of nitrogen to demonstrate that 60 to 100 percent of the current fishery production is supported by nutrients from fertilizer and sewage. Her research will be reported in the Jan. 21 online edition of the Proceedings of the National Academy of Sciences.
"This is really a story about how people unintentionally impact ecosystems," Oczkowski said.
Historically, the Nile would flood the delta every fall, irrigate nearby agricultural land, and flow out to the Mediterranean, carrying with it nutrients to support a large and productive fishery. Construction of the dam stopped the flooding, and the fishery collapsed.
"That's when fertilizer consumption in the country skyrocketed," said Oczkowski. "The Egyptians were fertilizing the land, and then fertilizing the sea with the run-off. It also corresponded with a population boom and the expansion of the public water and sewer systems."
As a result, landings of fish in coastal and offshore waters are more than three times pre-dam levels. While increased fishing effort in recent years may have played some role in the recovery, Oczkowski's findings indicate that anthropogenic nutrient sources have now more than replaced the fertility carried by the historical flooding.
Oczkowski and colleagues from URI, the U.S. Environmental Protection Agency, and the University of Alexandria collected more than 600 fish in 2006 and 2007 from four regions that received run-off from the delta and two areas not affected by the Nile drainage. Stable isotopes of nitrogen in each fish were measured and compared.
She found that the isotope signatures in the fish reflected two distinct sources of nitrogen: anthropogenic nitrogen from fertilizers and sewage in the fish caught in coastal and offshore areas of the delta, and nitrogen values consistent with the middle of the Mediterranean in fish caught in waters that were not affected by the delta drainage.
These results have raised questions among many scientists about the value of anthropogenic sources of nutrients to ecosystems.
"We're programmed in the West to think of nutrient enrichment of coastal systems as bad," Oczkowski said. "Here in Rhode Island we've spent hundreds of millions of dollars to upgrade sewage plants to reduce nutrient loading into Narragansett Bay. And it's a major issue in the Chesapeake Bay and in the Gulf of Mexico, where run-off of fertilizers from the country's breadbasket into the Mississippi River has caused a dead zone in the Gulf.
"But the Egyptians don't think it's a bad thing. For them, it's producing tons of fish and feeding millions of hungry people. It's forcing us to reconsider whether we can say that nutrient inputs are always a bad thing."
Can’t help but laugh heartily at this.
Practically the only reason I want to live a long life is so that I can still be here when all of the pseudo-science we’ve been subjected to gets exposed as the BS it is.
Hmmm... well, apparently you better RETHINK your .. FACT. Your RUNOFF SCARE is just as big a HOAX as GloBULL WARMING!! And another point.. Doubling the CO2 in our Atmosphere will not harm Humans and will quadruple crop yields. Methinks THOU DOST Protest too much!!
“Practically the only reason I want to live a long life is so that I can still be here when all of the pseudo-science we’ve been subjected to gets exposed as the BS it is.”
EggsAckley!
Heheheh.
That and seeing so many of the brain-dead liberal ideas discredited...
I think the Mississippi River dead zone is real. If someone would like to do something worthwhile then they might try to determine what is the difference between the Nile and Mississippi situations. Maybe the Mississippi runoff can be made beneficial.
A perfect day for bananafish.
The difference is that birth control pills and hormone replacement therapy is not being consumed by the Egyptian Nile population.
Give Egypt a few years and the endocrine mimicking compounds will build up and the aquatic habitat will come crashing down, as stories of mutant wildlife take over the Egyptian media.
They're covering Gaza now.
Great one!
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Because of this:this expansion, which followed a collapse of the fishery after completion of the Aswan High Dam in 1965...it's a GGG topic. As we all no doubt know, Pharaoh Ramesses' temples at Abu Simbel were moved to higher ground as the waters of Lake Nasser rose. |
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These are not your high-class fish.
I doubt there has been even one question raised by any scientist qualified to discuss the topic. If she werent fishing for grants, she would go visit David A. Bengtson, Professor & Department Chairman of URI Department of Fisheries, Animal and Veterinary Sciences. He could arrange for her to sit in on any of the entry level undergraduate aquaculture courses. Here she would discover that for thousands of years people without a PhD have known and taken advantage of the understanding that clear water, often mistaken as being synonymous with clean water, is dead water and that blooming nutrient rich green water is productive water.
So now that Ive saved the country millions in grants for research, do you suppose anyone will mail me a PhD?
The amount of fertilizer or the type of fertilizer? Beats me. But I think it would be worthwhile to discover what is the difference. Maybe it's something other than sewage or fertilizer.
bump
So... the Egyptian farmers compensated (unknowingly) by heavily fertilzing their irrigated croplands, "replenishing": the Nile nutrients that had been reduced in the natural flow of the river by the lake. Thus, in this rare case, excess fertilization made up for a man-made deficit of nutrients. So yes, here it's a good thing.
In most other places, the natural nutrient content of the rivers has been just fine, and agricultural activities leading to excess fertilizer runoff (as well as increased stormwater runoff due to more impervious surfaces in coastal areas) cause eutrophication: too much primary productivity, leading to decreased dissolved oxygen levels when the dead organic matter gets converted (by the well-known process of "respiration", in this case caused by bacteria) into inorganic matter. Same things happen in bacterial respiration as human respiration: oxygen in, carbon dioxide out. Eutrophic waters have low oxygen concentrations (particularly near the bottom) and that's why you get "dead zones").
I hope that clears things up a bit.
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