Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nile Delta fishery grows dramatically thanks to run-off of sewage, fertilizers

21.01.2009
Considered pollutants in the West, discharges help to feed millions in Egypt

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."

Todd McLeish | EurekAlert!
Further information:
http://www.uri.edu

More articles from Ecology, The Environment and Conservation:

nachricht When corals eat plastics
24.05.2018 | Justus-Liebig-Universität Gießen

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>