The findings, just published in the journal Freshwater Biology, raise concerns that climate change, over-pumping of aquifers for urban water use, and land management may permanently affect which species can survive. The research was supported by the National Science Foundation.
“Populations that have persisted for hundreds or thousands of years are now dying out,” said David Lytle, an associate professor of zoology at Oregon State University. “Springs that used to be permanent are drying up. Streams that used to be perennial are now intermittent. And species that used to rise and fall in their populations are now disappearing.”
The research, done by Lytle and doctoral candidate Michael Bogan, examined the effect of complete water loss and its subsequent impact on aquatic insect communities in a formerly perennial desert stream in Arizona’s French Joe Canyon, before and after severe droughts in the early 2000s.
The stream completely dried up for a period in 2005, and again in 2008 and 2009, leading to what researchers called a rapid “regime shift” in which some species went locally extinct and others took their place. The ecosystem dynamics are now different and show no sign of returning to their former state. Six species were eliminated when the stream dried up, and 40 others became more abundant. Large-bodied “top predators” like the giant waterbug disappeared and were replaced by smaller “mesopredators” such as aquatic beetles.
“Before 2004, this area was like a beautiful oasis, with lots of vegetation, birds and rare species,” Lytle said. “The spring has lost a number of key insect species, has a lot less water, and now has very different characteristics.”
The phenomena, the researchers say, does not so much indicate the disappearance of life – there is about as much abundance as before. It’s just not the same.
“Our study focused on a single stream in isolation, but this process of drying and local extinction is happening across the desert Southwest,” Bogan said. “Eventually this could lead to the loss of species from the entire region, or the complete extinction of species that rely on these desert oases.”
Small streams such as this are of particular interest because they can be more easily observed and studied than larger rivers and streams, and may represent a microcosm of similar effects that are taking place across much of the American West, the researchers said. The speed and suddenness of some changes give species inadequate time to adapt.
“It’s like comparing old-growth forests to second-growth forests,” Lytle said. “There are still trees, but it’s not the same ecosystem it used to be. These desert streams can be a window to help us see forces that are at work all around us, whether it’s due to climate change, land management or other factors.”
The researchers noted in their report that the last 30 years have been marked by a significant increase in drought severity in the Southwest. The drought that helped dry up French Joe Canyon in 2005 resulted in the lowest flow in Arizona streams in 60 years, and in many cases the lowest on record. At French Joe Canyon, the stream channel was completely dry to bedrock, leaving many aquatic invertebrates dead in the sediments.
That was probably “an unprecedent disturbance,” the researchers said in their report. Community composition shifted dramatically, with longer-lived insects dying out and smaller, shorter-lived ones taking their places.
Conceptually similar events have taken place in the past in plant communities in the Florida Everglades, floodplains in Australia, and boreal forests following fire disturbance, other researchers have found. In the Southwest, climate change models predict longer, more frequent and more intense droughts in the coming century, the scientists noted in their study.
About the OSU College of Science: As one of the largest academic units at OSU, the College of Science has 14 departments and programs, 13 pre-professional programs, and provides the basic science courses essential to the education of every OSU student. Its faculty are international leaders in scientific research.
The study this story is based on is available in ScholarsArchive@OSU: http://bit.ly/oA4LLz
David Lytle | EurekAlert!
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences