Download File - The Eurasian Ruffe

Julian Zea (Period 2)
Researching Invasive Species- The Eurasian Ruffe
(Source-Science.time.com)
Invasive species are organisms that are not natural, or alien, to a certain ecosystem. All
invasive species are harmful to the ecosystem they are alien to, or are predicted to be an
annoyance or pest in the future. For example, invasive species may eat other organisms in their
newfound homes, upsetting the balance that was once there. One invasive species is Eurasian
Ruffe, scientifically known as Gymnocephalus cernuus. This little fish poses a threat to all in the
Great Lakes region.
The Eurasian Ruffe is a small fish with a very large dorsal fin on its back and a scale-less
head. It usually stays well under a foot long, about six inches in length. This species is native to
northern Asia and temperate Europe. However, it was discovered in the Great Lakes region in
the western part of Lake Superior in 1986. Since then, it has been spotted in upper regions of
Lake Michigan and near Lake Huron. Like its Eurasian counterparts, it sticks to a diet of small
water insects and chironomids, small water organisms.
Researchers are not exactly sure how the Ruffe was introduced to the Great Lakes. One
possible and likely theory is that the small fish arrived in the Lakes through some ships’ ballast
water. Ballast water is water that is contained separately on some boats, allowing them to float
much better. This is especially useful on over- ocean travel, as it keeps ships from sinking
during rough storms. The Ruffe may have entered a container as it was being filled in Europe,
and traveled across the Atlantic without being noticed. It could have fed off the microorganisms
in the water. The ship then docked in the west of Lake Superior and released its ballast water to
refill the containers. The Eurasian Ruffe was free.
This fish is a threat to the ecosystems of the Great Lakes, especially now Lake
Superior. Many organisms in Lake Superior also feed on small insects and microorganisms,
causing a problem amongst the different species. However, the feature that makes the Eurasian
Ruffe stand out against its competitors is its quick reproductive cycle. The Ruffe is mature
enough to lay eggs at a young age of one year, and a female Ruffe can lay as many as 200,000
eggs a year. The increased amount of Ruffe allow them to overtake many other species in
hunting for food. Therefore, many species will die out due to starvation. Also, the Eurasian
Ruffe responds to biological changes faster than other fish species. The quick reproductive cycle
allow the Ruffe to produce more offspring, giving the entire species a better chance that a gene
within one fish’s DNA is resistant to things such as increased temperatures from climate
change. As the other fish species cannot cope with rising temperatures, the Ruffe adapts to its
environment and take resources that other species need. One last factor is the Ruffe’s
neuromasts. Neuromasts are organs that allow organisms to exceptionally feel vibrations in the
water. This allows the Ruffe to dodge predators and find prey better than other fish. Even
worse, the neuromasts in the Eurasian Ruffe advance over time, while other species’ decline over
time. This allows the Ruffe to have a better chance overall at getting food and surviving, while
other fish are left in Ruff's dust to perish.
If the Eurasian Ruffe continues to steal food from other organisms, negative effects on the
ecosystem will occur. Many species of fish will die out as they starve to death while the Ruffe
feasts on their food. As the Ruffe becomes the only fish left in Lake Superior, it will do three
things. The first would be to give the remaining predators of the Eurasian Ruffe a harder time at
surviving. As the Ruffe has better neuromasts than other fish, it can evade predators better. The
predators will soon die of starvation. The second would be to exhaust all of the remaining food
resources in Lake Superior. When the predators and competition are gone, the Ruffe is able to
increase its population numbers by many more. However, once the Lake's microorganisms are
depleted, the Ruffe will die, and the ecosystem with it. Once the water organisms pass away,
small land animals that depend on them will starve. Animals that eat those smaller organisms
will also starve, or migrate. It will take many years for the ecosystem of Lake Superior to be
revived as organisms migrate from other areas of the globe. The third is that the Ruffe will
migrate through rivers in the southern part of Lake Superior or travel around Lake Michigan, and
they will reach other lakes, such as Lake Huron. Once there, they can destroy and spread just
like they did in Lake Superior. More to the point, if they reach southern Lake Michigan, they
could travel through the Mississippi River to many other states. In a way, the entire country is at
a risk.
In the past, many methods have been used to attempt to rid Lake Superior of the Ruffe, but all
have failed. One tactic in 1989 was to use large amounts of native fish, such as the Yellow Perch
and Walleye, who are predators of of the Ruffe. This did cut back on the Ruffe population in
Lake Superior, back by 47%. However, the imported fish mostly went for native fish, and not
the Ruffe. The surviving Ruffe quickly repopulated the ecosystem. Another attempt to stop the
Ruffe was putting a chemical known as TFM. TFM is poisonous to many fish, including the
Eurasian Ruffe. However, the Ruffe is much more sensitive to TFM than other fish, so lower
amounts of it in water is more deadly to the Ruffe than other fish. Another way to chemically
subdue the Ruffe is by adding carbon dioxide in the water, which is used as an anesthetic for
fish. Both of these tactic work, but to an extent. Even though the Ruffe are taken care of, the
chemicals can be unpredictable and can harm native species. The Ruffe is a difficult species to
eliminate.
One tactic used on another invasive species might work against the Ruffe. The Brook trout is
an invasive species that harms the ecosystems in streams and rivers in Montana. Ecologists have
used backpack electrofishing to rid Montana of the trout. First, workers wearing backpacks that
hold electric batteries head into streams that hold the trout. They then use a pole to give the
water a small electric shock, which attracts nearby fish. A stronger shock is then applied to the
water, which stuns the fish. The trout are picked up to be cooked, and the native species are sent
back in the water. This has lead to the elimination of the trout in the fished areas. There is also a
larger version for lakes and oceans, on a boat. This tactic would be able to stop the Eurasian
Ruffe from spreading out into other lakes and rivers, and it could start to push the Ruffe back to
Lake Superior and even eradicate them.
The Eurasian Ruffe is a problem to the United States. It eats the food that belongs to native
fish and is hard to stop. Using chemicals and predators are ineffective and harmful. However,
using electricity to catch the Ruffe may be the most effective way to get rid of them. If you see a
Ruffe in your area, please net it or alert officials.
Sources:
Riven, G. (2014, November 24). Getting Rid of Invasive Species With a Little Electric
Shock. Discovermagazine.com. Retrieved from http://blogs.discovermagazine.com/dbrief/2014/11/24/invasive-species-electric-shock/
Sea Grant Minnesota. (2015, March 30). Eurasian Ruffe (Gymnocephalus cernuus). Retrieved
May 21, 2015, from http://www.seagrant.umn.edu/ais/ruffe.
U.S. Geological Survey (USGS). (2015, April 8). Gymnocephalus cernuus (Linnaeus,
1758). Retrieved May 21, 2015, from http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=7.