Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Zebra mussels hang on while quagga mussels take over

16.06.2009
The zebra mussels that have wreaked ecological havoc on the Great Lakes are harder to find these days — not because they are dying off, but because they are being replaced by a cousin, the quagga mussel. But zebra mussels still dominate in fast-moving streams and rivers.

Research conducted by Suzanne Peyer, a doctoral candidate in the University of Wisconsin-Madison Department of Zoology, shows that physiological differences between the two species might determine which mollusk dominates in either calm or fast-moving waters.

"Zebra mussels quite rapidly colonized rivers close to the Great Lakes right after their introduction, within a year or two," Peyer explains. "Quagga mussels were introduced in the Great Lakes around 20 years ago, but they are still not found in the rivers or tend to be present in low numbers."

The mussels are similar in many ways. Their habitats overlap, and both are suspension feeders that filter water to extract their food. But the cousin species are different in many ways, too. Zebra mussels prefer to attach to a hard surface, while quagga mussels can live on soft bottoms, such as sand or silt. Zebra mussels also prefer warmer water temperatures and do not grow as big as quagga mussels.

Peyer's research focused on the ability of the mussels to attach to underlying material. Both species attach to rocks, sand, silt or each other by producing tiny but strong "byssal" threads, string-like strands of protein. These threads act as an adhesive that enable the mussels to attach to surfaces, regardless of how slippery the surface is. Byssal threads are the reason mussels are so difficult to remove from boats or water intake pipes.

Peyer collected both mussel species from Lake Michigan. In the lab, she subjected the mussels to different water velocities that simulated river flow conditions. Her research results supported her hypothesis that zebra mussels are able to produce more byssal threads than quagga mussels, enabling them to attach more securely to underlying material. They are also better able to hang on where water is flowing, such as in a river or stream.

"The results were that zebra mussels produced byssal threads at about twice the rate of quagga mussels," Peyer says. "Zebra mussels can ramp up their byssal thread production under different flows."

A statistical model Peyer developed also predicted that, with increasing velocity, zebra mussels produce more threads than quagga mussels.

According to this model, the zebra mussels show high plasticity, or the ability to adapt to changing environmental conditions. Plasticity can be an adaptive characteristic that allows an organism to survive under new conditions. In this case, the new condition is increased flow.

Zebra mussels are also able to stay attached better. At the highest velocity, only 10 percent of the zebra mussels detached, but 60-70 percent of the quagga mussels detached.

Results from her research, funded by the UW-Madison Sea Grant Institute, is published in the July 1 issue of the Journal of Experimental Biology.

According to Peyer's research adviser, Professor Carol Eunmi Lee at the UW-Madison Center of Rapid Evolution, no one has previously looked at differences in attachment between these species as an explanation for their distribution patterns in North America.

"It's the first time somebody actually went and systematically looked at functional differences between the two species that would explain the different kinds of substrate that they could invade," she says. "In that sense, Suzanne has produced a really elegant and clever study. It has very concrete hypotheses and results."

Zebra mussels were first introduced in the Great Lakes in the late 1980s, hitchhiking their way into North America in the ballast water of ships from the Caspian and Black Seas. Within a few years, zebra mussels had colonized shallow water, beaches, and water intake pipes in layers up to eight inches thick. Although quagga mussels came onto the scene a few years later, they have recently become the dominant species in calm waters of the Great Lakes.

These mussels have permanently changed the ecosystem. Before the mussels invaded, Lake Michigan water was mostly cloudy and millions of tiny microorganisms provided a food base for fish. Because the mussels filter the microorganisms, the waters today are surprisingly clear, allowing light to penetrate to greater depths, which in turn promotes prolific, nuisance algae blooms.

Quagga mussels may be the reason Diporea, a small shrimp-like species that serves as a food source for larger fish, is no longer abundant. The whitefish that feed on Diporea are growing to less than half of their expected size.

Both Peyer and Lee hope that understanding the biological differences between the two mussel species will help those who manage the Great Lakes.

"We need to be aware of the distinct differences between the two species," Peyer says. "If we understand the differences in their biology, we might help to make management more efficient and more effective in the end."

Suzanne Peyer | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Life Sciences:

nachricht Water world
20.11.2017 | Washington University in St. Louis

nachricht Carefully crafted light pulses control neuron activity
20.11.2017 | University of Illinois at Urbana-Champaign

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>