Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lake research offers clues to managing crayfish invasions

02.08.2004


Rusty crayfish, an invasive species now crawling across the rocky bottoms of lakes and streams throughout the United States and Canada, may not always have a stronghold once they enter these bodies of water.

The findings, part of an ongoing study at the University of Wisconsin-Madison, suggest that the type of interaction among rusty crayfish, fish and aquatic plants may tip the scale, favoring either the invader or native species. This knowledge, the researchers note, may lead to new strategies for removing these trespassers.

Details of the research will be presented Wednesday, Aug. 4, at the annual meeting of the Ecological Society of America in Portland, Ore.



Native to the streams of Ohio, Kentucky and Tennessee, rusty crayfish - measuring up to five inches long - have slowly infiltrated lakes far and wide, including those in New Mexico and Ontario.

Once used for bait, rusty crayfish now are partly responsible for anglers’ declining number of fish catches because they alter fish habitat, ultimately altering fish populations.

For example, these intruders eat fish eggs, displace animals native to the waters and "mow down" aquatic plants - a source of food and shelter for fish, says Brian Roth, a graduate student at UW-Madison’s Center for Limnology and a presenter at the meeting. "They have really dramatic and traumatic effects on the ecosystem."

To date, the promise of successfully removing rusty crayfish and restoring the habitat has been bleak. For example, bait traps tend to catch only the largest rusty crayfish, and biocides, chemicals proven to wipe them out, obliterate everything else in the lake.

But one strategy for managing these invaders once they enter a lake might come from Roth’s preliminary data showing that lakes - even ones similar in water chemistry and the amount of rocky substrate crayfish call home - can have either a low or high abundance of these invaders.

Donning his scuba gear, Roth went underwater to better understand why rusty crayfish are more abundant in certain lakes. During a three-year period, he surveyed six lakes and collected the rusty crayfish that crawled across the rocky bottom in each sampling area. The number of crayfish ranged from just five per square meter in one lake to around 200 in another, the majority of which were newborn crayfish.

Roth and his collaborators then compared the number of crayfish in each sampling area to data collected by another UW-Madison group studying the number of fish and aquatic plants in those same areas.

They found that two of the testing lakes, just five miles apart and similar in water chemistry, looked very different underwater in terms of rusty crayfish, fish and plant life. While Big Lake had a high abundance of the invasive species, but low abundance of bluegills and plants, Wild Rice Lake showed the opposite.

The preliminary findings, says Roth, suggest that alternate states of rusty crayfish abundance exist among lakes. In other words, they can either dominate or be a minor influence. This can happen, he adds, because of the interaction among fish, their habitat and rusty crayfish.

When the crayfish population is small, Roth explains, there tend to be more fish, which feed heavily on the baby crustaceans and, as a result, prevent them from reaching adulthood and reproducing. However, when the crayfish population is large, he says, they overwhelm their predators by producing more offspring and destroying the plant life that protects fish.

"That these alternate states exist gives us some hope that we might be able to take lakes infested by rusty crayfish and force the system from one state to another," says Roth.

To test this theory, he and other researchers are conducting an experiment in which they have set up 300 rusty crayfish traps at the bottom of a 150-acre lake in northern Wisconsin. The objective is to determine whether fish and aquatic populations, decimated by the invaders, will grow in number as crayfish are removed.

Stephen Carpenter, a UW-Madison zoology professor and researcher at the Center for Limnology who is involved in this research, says: "If there is a tipping point in rusty crayfish ecology - so we can drive the crayfish to low levels using natural predation, plus heavy harvest by people - then we may have a tool for restoring the lakes that have been damaged by crayfish invasions."

Brian Roth | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Shrews shrink in winter and regrow in spring

24.10.2017 | Life Sciences

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>