Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Midges send undeniable message -- planet is warming

13.12.2006
Small insects that inhabit some of the most remote parts of the United States are sending a strong message about climate change. New research suggests that changes in midge communities in some of these areas provide additional evidence that the globe is indeed getting warmer.

Researchers created a history of changing midge communities for six remote mountain lakes in the western United States. Midges, which resemble mosquitoes but usually don't bite, can live nearly anywhere in the world where there is fresh water.

The insect remains revealed a dramatic shift in the types of midges inhabiting these lakes in the last three decades, said David Porinchu, the study's lead author and an assistant professor of geography at Ohio State University.

“Climate change has had an overriding influence on the composition of the midge communities within these lakes,” he said. “The data suggest that the rate of warming seen in the last two decades is greater than any other time in the previous century.”

The data suggest that, starting around 25 years ago, warmer-water midges began to edge out cooler-water midge species around these remote lakes.

“People would like to believe that these mountainous environments may be immune to climate change, but these are some of the first areas to feel the impact of warmer temperatures,” Porinchu said.

He and his colleagues presented their findings December 15 in San Francisco at the annual meeting of the American Geophysical Union.

The researchers gathered sediment from six small lakes in the Great Basin of the western United States – a vast watershed bounded roughly by the Sierra Nevada and Rocky Mountain ranges. Since the lakes are accessible only by foot trail, the researchers carried in an inflatable raft during the summer months in order to collect sediment samples from the middle of the lakes. The lakes range from 8.2 feet (2.5 meters) to 34.5 feet (10.5 meters) deep.

The scientists collected sediment in cylindrical plastic tubes, gathering several samples from each lake. They didn't need much sediment – just four inches (10 cm) of lake-bottom residue can represent nearly 100 years' worth of sedimentation, Porinchu said.

“The amount of sediment that trickles out of the water column to the bottom of these lakes every year is so low because these lakes are at such high elevations – few, if any, trees grow at these elevations,” he said. “There just isn't much material entering the lakes.”

Once they were back in the laboratory, the researchers sliced the sediment cores into thin slivers about 0.2 inches (0.5 cm) thick. Each sliver represents a five or 10-year span, Porinchu said. They calculated the age of single sediment layers by using lead-210, an isotope of lead that decays at a constant rate and, therefore, can serve as a chronological aid.

Using a microscope, the researchers then searched the sediment for larval remains of the midges. Specifically, they were looking for larval head capsules, which are made of a hard, semi-transparent material called chitin. These head capsules become embedded in sediment once they are shed. Chitin, also a component of insect exoskeletons and the shells of crustaceans, doesn't readily degrade in the sediment of these lakes.

The researchers determined the type of midges that lived in the lakes based on specific variations in certain head capsule structures, such as differences in the number, size, shape and orientation of teeth.

“In the upper layers of most of the sediment samples – those representing the last 25 to 30 years – we see head capsules from midges that normally thrive in slightly warmer water temperatures,” Porinchu said. “And the cooler-water midges have nearly, or completely, disappeared.”

Surface water temperatures in these lakes have risen anywhere from 0.5 to 1 degree since the 1980s.

“Although that doesn't seem to be a huge increase, just a slight fluctuation in water temperatures can significantly affect the rate of egg and larval development,” Porinchu said.

And the majority of midge species living in these six lakes in the last 30 years thrive in temperatures ranging from 58.8 to 60 degrees F (14.9 to 15.6C), while cooler-water midges prefer temperatures in the 57 to 58.1F (13.9 to 14.5C) range.

“Above-average surface water temperatures typified the late 20th century in all of the lakes that we studied,” Porinchu said. “It's clearly an indication that something is happening that is already affecting aquatic ecosystems in these fragile, high-elevation lakes.”

Porinchu conducted the study with researchers from the National University of Ireland in Galway; the University of California, Los Angeles; the University of Western Ontario in London, Ontario; and Middlebury College in Middlebury, Vt.

David Porinchu | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>