Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Loss of just one species makes big difference in freshwater ecosystem

22.08.2006
Researchers at Dartmouth, Cornell University, and the University of Wyoming have learned that the removal of just one important species in a freshwater ecosystem can seriously disrupt how that environment functions. This finding contradicts earlier notions that other species can jump in and compensate for the loss.

Brad Taylor, currently a research associate in the department of biological sciences at Dartmouth, and his colleagues studied a fish called the flannelmouth characin (Prochilodus mariae) native to South American rivers. This particular fish eats detritus, the fine organic matter on the river bottom, and because of this, it plays a critical role in regulating the breakdown and transport of carbon in the rivers.

"This fish species is a popular food source; it is harvested regularly, and in some cases, it's overfished," says Taylor, the lead author on the study that was published in the August 11 issue of the journal Science. "We learned that removing this particular fish greatly altered the metabolic activity of the river ecosystem. Other fish species did not compensate for the lack of Prochilodus, an effect consistent with observations from other rivers where they have been excluded much longer by dams."

The researchers used a heavy, plastic divider to split a 210-meter stretch (a little more than a tenth of a mile) of Rio Las Marías in Venezuela into two separate river sections. On one side, they removed only Prochilodus, and on the other, all the fish remained. The team then took a series of measurements upstream and downstream to quantify the transport of particulate organic carbon (POC).

"Although there are more than 80 fish species in this small river, the detritivores, like Prochilodus, make up 50-80 percent of the fish biomass. Their abundance makes them attractive targets for harvesting by people. So when we took them away, not only was the impact astounding, it also revealed how their loss could change carbon flow, an important measure of ecosystem function," says Taylor.

During a six-year period, Taylor and his team discovered a strong association between Prochilodus abundance and the downstream transport of POC. With Prochilodus present, the organic carbon was distributed more evenly along the length of the river. Without Prochilodus present, large amounts of organic carbon accumulated in upstream areas, and it was consumed by bacteria, and therefore not readily available to organisms living farther downstream. In contrast to other migratory fish species, like salmon, that provide nutrients to the river (in the form of their carcasses), this species modifies the availability of nutrients through its activities. The researchers learned that the loss of Prochilodus increased the rate at which organic carbon was converted to carbon dioxide, which could increase the flux of carbon dioxide from the river to the atmosphere, a topic Taylor will be exploring in the coming months.

"We also used the wealth of information contained in museum specimens of Prochilodus collected over the past 28 years from throughout the Orinoco basin in Venezuela to document that the maximum body size of individuals has declined dramatically, from about 2.2 pounds to a half a pound, which is a hallmark of overharvested populations" says Taylor. "Although over hundreds or thousands of years other species may fill the role played by Prochilodus, but people and other organisms are highly dependent on the services provided by Prochilodus now. We hope that our study draws the attention of governments and scientists to protect and study the importance of the smaller and more abundant organisms, which constitute most of the Earth's biodiversity and are now being heavily targeted by humans. In many parts of the world this task will not be easy because there is little enforcement of existing fishing laws and many people depend on such species as their primary source of affordable animal protein."

Taylor's research is funded by the National Science Foundation.

Sue Knapp | EurekAlert!
Further information:
http://www.Dartmouth.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>