Featured Research

from universities, journals, and other organizations

Loss Of Just One Species Makes Big Difference In Freshwater Ecosystem, Study Finds

Date:
August 21, 2006
Source:
Dartmouth College
Summary:
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.

The flannelmouth characin is native to South American rivers.
Credit: Photo by Brad Taylor

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 Marνas 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.


Story Source:

The above story is based on materials provided by Dartmouth College. Note: Materials may be edited for content and length.


Cite This Page:

Dartmouth College. "Loss Of Just One Species Makes Big Difference In Freshwater Ecosystem, Study Finds." ScienceDaily. ScienceDaily, 21 August 2006. <www.sciencedaily.com/releases/2006/08/060818175119.htm>.
Dartmouth College. (2006, August 21). Loss Of Just One Species Makes Big Difference In Freshwater Ecosystem, Study Finds. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2006/08/060818175119.htm
Dartmouth College. "Loss Of Just One Species Makes Big Difference In Freshwater Ecosystem, Study Finds." ScienceDaily. www.sciencedaily.com/releases/2006/08/060818175119.htm (accessed August 22, 2014).

Share This




More Plants & Animals News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Drug Used To Treat 'Ebola's Cousin' Shows Promise

Newsy (Aug. 21, 2014) — An experimental drug used to treat Marburg virus in rhesus monkeys could give new insight into a similar treatment for Ebola. Video provided by Newsy
Powered by NewsLook.com
Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Terrifying City-Dwelling Spiders Are Bigger And More Fertile

Newsy (Aug. 21, 2014) — According to a new study, spiders that live in cities are bigger, fatter and multiply faster. Video provided by Newsy
Powered by NewsLook.com
Lost Brain Cells To Blame For Sleep Problems Among Seniors

Lost Brain Cells To Blame For Sleep Problems Among Seniors

Newsy (Aug. 21, 2014) — According to a new study, elderly people might have trouble sleeping because of the loss of a certain group of neurons in the brain. Video provided by Newsy
Powered by NewsLook.com
Ramen Health Risks: The Dark Side of the Noodle

Ramen Health Risks: The Dark Side of the Noodle

AP (Aug. 21, 2014) — South Koreans eat more instant ramen noodles per capita than anywhere else in the world. But American researchers say eating too much may increase the risk of diabetes, heart disease and stroke. (Aug. 21) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins