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 How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

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

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>