Their findings appear in a current online issue of the journal Freshwater Biology where they describe experiments that examined some effects of fisheries management practices now in use in California mountain lakes where fish do not naturally occur.
The research has value because the vast majority of mountain lakes in the western United States have been stocked with trout for several decades. Studies following lake restoration to fishless conditions will help scientists and wildlife managers understand the impact of past actions and future decisions.
Since 2000, the California Department of Fish and Game has reduced the number of wilderness lakes it stocks by about half because non-native fish feed on declining species like the Sierra Nevada yellow-legged frog. Federal and state agencies have also begun removing introduced trout in some lakes because fish can survive for years and continue feeding on sensitive species, after stocking has ceased.
Until now, scientists seldom studied the response of aquatic insect populations to the removal of non-native trout.
"These highly-mobile predators don't naturally occur in small alpine lakes so they have significant top-down effects on ecosystems," said Karen Pope, a Forest Service scientist at the Pacific Southwest Research Station and one of the study's authors. "They prey upon aquatic insects that are also food for other insects, amphibians, birds and bats."
In 2003, Pope and her colleagues began testing the effects introduced fish had on lake ecosystems in 16 lakes in Northern California's Trinity Alps Wilderness.
The National Science Foundation, U.S. Forest Service, California Department of Fish and Game, and University of California funded the study, which matched current California fisheries management practices by including lakes with continued stocking of trout, suspension of stocking and removal of all fish. It also included fish-free lakes as reference sites for the study.
The researchers used floating nets on each lake's surface to quantify aquatic insect populations. They also used gill nets to sample trout density at lakes where there was continued stocking or suspension of stocking.
Their results showed the presence of introduced trout was the most important factor affecting the emergence of insects from the lakes.
Aquatic insect populations quickly increased when trout were removed from lakes. However, the scientists found suspension of stocking was not effective for restoring insect abundance in most lakes. This was not surprising because suspension of stocking alone had little effect on trout density, according to the researchers.
Roland Giller | EurekAlert!
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
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