Featured Research

from universities, journals, and other organizations

Health check for European streams

Date:
June 20, 2012
Source:
EAWAG: Swiss Federal Institute of Aquatic Science and Technology
Summary:
In a unique field experiment, ten research groups from nine different countries have studied the ecological status of 100 streams across Europe. This was the first study to make extensive use of leaf-litter breakdown as an assessment method.

Caddisfly larvae (Trichoptera) are highly efficient shredders of leaf litter in surface waters.
Credit: Photo J.J. Casas

In a unique field experiment, ten research groups from nine different countries have studied the ecological status of 100 streams across Europe. This was the first study to make extensive use of leaf-litter breakdown as an assessment method. The findings of the study -- in which Eawag played a key role -- are reported in the latest issue of Science.

To assess the condition of rivers and streams, environmental scientists generally measure variables such as temperature, acidity and nutrient concentrations. They also determine the composition of the benthic macroinvertebrate community -- insect larvae and other small streambed organisms. This method was originally developed to assess water pollution caused by wastewater. But today, surface waters are exposed to a more complex range of stressors: freshwater ecosystems may be severely impaired by bank reinforcement, weirs and altered flow regimes as well as by cocktails of chemical pollutants, invasive species and the effects of climate change.

According to biologist Professor Mark Gessner, this means that the existing measures are no longer adequate for assessing an ecosystem as a whole: "Just as a patient can be ill without having a temperature, rivers and streams with clean water can still have a lot of other problems as ecosystems." Also crucial to ecosystem health, he points out, is the functioning of processes which are characteristic of natural systems -- an aspect which has been neglected to date in the assessment of surface waters.

Gessner and his colleagues therefore tested a new method based on one such process -- the breakdown of leaf litter. "Litter input is the main source for stream food webs and is of major importance for whole-system metabolism," says Gessner, who carried out the investigations with the research group he formerly led at Eawag (he now works at the Leibniz Institute of Freshwater Ecology and Inland Fisheries and at the TU Berlin). Leaf litter is broken down largely by microscopic fungi -- some of which are noted for their bizarrely shaped spores -- and by benthic macroinvertebrates.

The researchers deployed mesh bags filled with oak and alder leaves in 100 streams in France, the UK, Ireland, Poland, Portugal, Romania, Spain, Sweden and Switzerland. They then determined how long it took for half of the leaf litter to be broken down -- a measure analogous to the half-life of radioactive elements. In some of the streams, they also determined the number and diversity of benthic macroinvertebrate species, as well as concentrations of phosphate and inorganic nitrogen compounds.

It was found that low-nutrient waters contain few organisms which can make efficient use of litter resources. Conditions in heavily enriched waters are likewise unfavourable for organisms of this kind. Breakdown rates were thus low in both cases. With intermediate nutrient concentrations, however, no correlation was observed between concentrations, benthic macroinvertebrates and breakdown rates. Accelerated litter breakdown may thus indicate impairments caused by nutrients in cases where conventional methods would suggest good water quality -- i.e. where nutrient concentrations are relatively low.

Gessner believes that this method has significant potential: "Just 'taking the patient's temperature' is certainly no longer a reliable way of checking the health of streams and rivers in Europe. Modern assessment of freshwater ecosystems calls for the kind of differential diagnosis which we take for granted in medicine -- identifying the underlying causes of symptoms on the basis of additional criteria. Here, processes such as litter breakdown can make an important contribution."


Story Source:

The above story is based on materials provided by EAWAG: Swiss Federal Institute of Aquatic Science and Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. G. Woodward, M. O. Gessner, P. S. Giller, V. Gulis, S. Hladyz, A. Lecerf, B. Malmqvist, B. G. McKie, S. D. Tiegs, H. Cariss, M. Dobson, A. Elosegi, V. Ferreira, M. A. S. Graca, T. Fleituch, J. O. Lacoursiere, M. Nistorescu, J. Pozo, G. Risnoveanu, M. Schindler, A. Vadineanu, L. B.- M. Vought, E. Chauvet. Continental-Scale Effects of Nutrient Pollution on Stream Ecosystem Functioning. Science, 2012; 336 (6087): 1438 DOI: 10.1126/science.1219534

Cite This Page:

EAWAG: Swiss Federal Institute of Aquatic Science and Technology. "Health check for European streams." ScienceDaily. ScienceDaily, 20 June 2012. <www.sciencedaily.com/releases/2012/06/120620113137.htm>.
EAWAG: Swiss Federal Institute of Aquatic Science and Technology. (2012, June 20). Health check for European streams. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2012/06/120620113137.htm
EAWAG: Swiss Federal Institute of Aquatic Science and Technology. "Health check for European streams." ScienceDaily. www.sciencedaily.com/releases/2012/06/120620113137.htm (accessed July 24, 2014).

Share This




More Earth & Climate News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Observation Boat to Protect Cetaceans During Ship Transfer

Observation Boat to Protect Cetaceans During Ship Transfer

AFP (July 22, 2014) As part of the 14-ship convoy that will accompany the Costa Concordia from the port of Giglio to the port of Genoa, there will be a boat carrying experts to look out for dolphins and whales from crossing the path of the Concordia. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com
New Orleans Plans to Recycle Cigarette Butts

New Orleans Plans to Recycle Cigarette Butts

AP (July 21, 2014) New Orleans is the first U.S. city to participate in a large-scale recycling effort for cigarette butts. The city is rolling out dozens of containers for smokers to use when they discard their butts. (July 21) Video provided by AP
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 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