The Great Lakes just can't catch a break. According to research, not only are the lakes already home to a number of non-native species, but they are also bound to keep on getting invaded, with the killer shrimp poised to become the next big threat.

In the last two centuries, over 180 non-native species have already found their way into the Great Lakes as well as the rivers flowing into them. Almost 20 percent of these species are harmful to the economy and ecology in the area, posing threats to the multibillion dollar fishing industry and native biodiversity.

According to researchers, most of the new threats emerging are brought about by climate change and live trade.

With the importation of live plants and animals for use as aquarium pets and bait fish or to be sold in food markets, live trade will continue to expand in the years to come and is seen by researchers as one of the foremost reasons the Great Lakes could be overrun by non-native species within 50 years, based on a pessimistic scenario they crafted about the future of the water system.

This pessimistic scenario also factored in the failure of regulations on ballast waters to be effective in preventing the introduction of invasive species into the Great Lakes coming from a region surrounding the Black Sea. Some of the most disruptive species to enter the Great Lakes, such as the zebra mussel, came from this region, and more will be coming to North America, such as the killer shrimp.

For the status quo scenario, researchers envisioned there will be no new protection policies in place to keep non-native species at bay, but ballast water regulations are proving to be effective. Live trade is still in play in this scenario and will still be offering the most threat. Since new regulations in 2006 and 2008, ships now are required to dump their fresh-water ballast and fill ballast tanks with salt water before entering the St. Lawrence Seaway, a move which is protecting the fresh-water lakes because salt-water animals can't survive there.

In the optimistic scenario, researchers put invasion risk at a minimum due to the harmonious implementation of policies by the United States and Canada. Invasion is an issue involving borders, so those on either side of the line must work together.

"In addition to harmonized regulations on live trade, the two countries must coordinate early detection and rapid response to new threats -- before an invasion has progressed beyond control," said Anthony Ricciardi, a biologist specializing in invasive species. He also supervised the study.

If waters in the Great Lakes warm because of climate change, warm-water species from the Mississippi River could also invade the lakes from the south via the canal that connects the river to the lakes.

The study, published in the Journal of Great Lakes Research, involved researchers from McGill University, the State University of New York at Plattsburgh, Trent University, York University and the University of Michigan.

The "killer shrimp" scientists are worried about under the pessimistic scenario are originally from near the Black and Caspian Seas. In the past 20 years, the shrimp have spread across central and western Europe via the Danube and Rhine. It grows rapidly, reaches sexual maturity early, can reproduce all year round, and lays nearly 200 eggs per clutch. It also has wide food preferences and can tolerate wide ranges of water temperature, salt and oxygen levels. It also can survive for at least six days out of water.

Its scientific name is Dikerogammarus villosus. It is about an inch long, but its large mandibles make it an aggressive predator and it is notable for its tendency to kill even when not hungry.