RFD News Intern

Voyagers to the lake expect the same things -- boats, sand and miles of open water.

Unfortunately, those who visit Lake Erie are in for more than they bargained.

For years, different species of marine animals have invaded the waters, causing aquatic aches for both humans and fish. Now, researchers have battened down the hatches on these nautical nuisances in the hopes of finding ways to control their populations and get back to smooth sailing.

Zebra mussels, or Dreissena polymorpha, are thought to have arrived in North America from ballast water of ocean-going ships from Eastern Europe. These clam-like creatures were first discovered in 1988 at Lake St. Clair, about six miles northeast of Detroit. Shortly after, the species trickled down to Lake Erie, and in less than 10 years, zebra mussels and their cousins, Quagga mussels, spread to all five Great Lakes.

One reason for their extensive migration is because of the size of its young. During this stage, zebra mussels are roughly the diameter of a human hair and are invisible to the naked eye, making them easily spread by water currents. Older mussels are larger and remain stationary by attaching themselves to hard surfaces, including pipes, buoys, docks and boats.

"When they first arrived, no one knew what to do, so we had to figure it out," said Guy Tibbel, a captain at Tibbel's Marina and Charter Service in Marblehead.

The Tibbel family has been in the charter business since 1921, which means they have plenty of experience adapting to lake invaders. When it comes to mussels, they've learned how to keep them from being a pain on the bottom.

"We spray the underneath of our boats with an anti-fouling paint that contains no tin or copper," said Jack Tibbel, Guy's father and a captain himself. "It goes on clear and it keeps the mussels from attaching to the bottom of the boats."

Though marinas have control over those unwanted inhabitants, some parts of Lake Erie have recorded mussel densities over one million per square-meter and have caused power companies, city water suppliers and swimming areas to increase their costs in order to afford the removal of the invaders. The U.S. Fish and Wildlife Service has estimated the economic impact over the next 10 years within the Great Lakes region alone to be in the billions.

Although the mussels extend from the eastern to western basin of Lake Erie, the Ohio Department of Natural Resources (ODNR) reported the numbers have not increased this year, mostly because they just have no where else to cling.

"Density of the mussels have leveled off, with mussels likely colonizing all the available substrate," said Jeff Tyson, biology supervisor at the Sandusky Fisheries Research Unit of the ODNR.

Despite the problems these intruders cause, they can actually be beneficial. Each of the filter-feeders can sift through up to one gallon of water per day, improving the clarity of the water from six inches to 30 feet in some areas.

Though efforts to develop a species-specific control agent are underway, until then, the massive number of mussels continue to survive. But they are not the only invaders from Eastern Europe to make it to Lake Erie -- another species made a similar journey to the Great Lakes.

The round goby, also known as Neogobius melanstomus, wandered into the Great Lakes region in 1990 through the exact same entry as the zebra mussels. They were confirmed in Lake Erie in 1994 and since then have increased in population. And though their numbers are large, when it comes to density, they are just like their smaller European friends.

"Round goby densities appear to have stabilized in Lake Erie as well, with density estimates of over 1,500 per acre in rocky areas," said Tyson.

Goby adults tend to be about seven inches or less in length in the Great Lakes region and are usually a gray, brown or black color. They generally prefer shallow areas, which makes Lake Erie a perfect spot to maintain a goby habitat. Despite their tiny, innocent appearance, these fish are actually little troublemakers in the marine world.

With a sort of Napoleon complex, these fish are very aggressive against much bigger opponents in the area. Gobies have been known to compete with native fish for food and space. Ecologically, these invaders can rapidly spread contaminants into sport-fish who feed on them after the goby has consumed zebra mussels containing harmful particles. But even though they can cause harm, they are not all bad.

"Round goby influence the flow of energy in Lake Erie from the benthic to the pelagic food web," Tyson said. "[Unfortunately] they are very effective nest and egg predators that have had a negative impact of smallmouth bass populations."

Well, every creature has its faults. Although scientists are beginning tests to create electric barriers to control the spread of round gobies, they are too widely distributed at this time for an effective treatment to take hold. Even though these little guys are menaces, they do not "suck" as much as other lake invaders.

The sea lamprey, Petromyzon marinus, originated in the Atlantic Ocean and made its way to the Great Lakes through canal lock systems in the early 20th century. One of the first invaders of the lakes, it is a parasitic species that feeds on the blood of host fish, which are either scarred or killed from its wounds. Because each one can kill 15 to 40 pounds of fish, sea lampreys are also the cause of decline in some of the native populations in the lakes.

"Sea lampreys have been enormously destructive since they invaded the Great Lakes," said Tyson. "They effectively wiped out the population of lake trout in many of the Great Lakes."

After being discovered in Lake Erie in 1921, their long, snake-like stature, caused people to often mistake them for eels, but their tooth-ridged suction cup mouths and many hazardous characteristics quickly set them apart from the common sea serpent.

Sea lampreys are capable of living in salt and fresh waters and produce large numbers of eggs during their pregnancies. Also, they have few predators against them in the Great Lakes, causing them to be able to easily expand their communities.

Thankfully, through the efforts of a group of Michigan scientists, the sea lamprey is one lake invader which is now actually being controlled. In 1955, the Great Lakes Fishery Commission was created with the hopes of restoring fisheries in its waters. One of the first goals of the group was to manage the sea lamprey population. Over 50 years later, the GLFC has successfully reached its objective.

"Sea lampreys are declining in Lake Erie through the efforts of the GLFC," said Tyson. "They are charged with sea lamprey control and using a number of techniques of treatment."

Through lampricide, barriers, tributary treatments, sterile male release techniques and trapping, these scroungers are slowly being filtered out of the Great Lakes. And though the drop in population may be unbelievable to some, the actual existence of another lake creature is unbelievable to most.

Freshwater jellyfish, or Craspedacusta sowerbyi, were transported to the United States by ornamental aquatic plants from China in 1880. Since then, they have been recorded in 44 states and the District of Columbia. The jellyfish made their debut in Lake Erie in 1933 through the seemingly common transport of lake invaders, Lake St. Clair.

They appear as a bell-shaped sticky mucous, possessing five opaque-white, greenish canals and four very long tentacles for feeding and stability. Though their saltwater brethren can grow to be as large as a bed, freshwater jellyfish only expand from about the size of a penny to the size of a quarter.

Both sexually and asexually, freshwater jellyfish only produce sporadically, and may go several years between blooms, making them extremely rare. Blooms are dependent upon temperature, zooplankton populations and alkalinity on water conditions. Unfortunately, these creatures appear to be virtually unseen in Lake Erie.

"There was a bloom of freshwater jellyfish in Lake St. Clair in 2007," said Tyson. "I have seen blooms of them, but not in Lake Erie."

Others in the lake area have spotted the tiny jellies in the past, but this year, they seem to be taking a break from Lake Erie.

"We used to find them covering our dock bumpers," said Jack Tibbel. "But so far this season, we haven't seen any."

Seen or unseen in the lake, the squishy fish exists. The impact of the jellyfish on the ecosystem is unclear, yet they are known to feed on small organisms within its reach, paralyzing them with their powerful stings. Luckily for water-lovers who may be afraid of getting nipped themselves, their nematocysts are too small to penetrate human skin.

Someone bring back Oliver Hazard Perry, the lake has been invaded again. Fortunately, scientists and mariners are battling hard against the foreign creatures so that visitors can once again take on the tides without these bothers at their sides.