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 Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>