Scientists are concerned that the fast-growing invasive snail snail discovered in Lake Michigan could adversely affect the region's ecosystem. New Zealand snails living in mud join the list of non-native species introduced into the Great Lakes system, threatening to break down the food chain and change the local environment.
Scientists who tested Lake Michigan water samples last summer found New Zealand mud snails, the Illinois Natural History Survey said. They only grow to a few millimeters in size - a few dozen can lie on a coin - making it difficult to detect them.
Large snails of asexual snails, they have no natural predators in North America, said scientist Kevin Cummings, who works for the Natural History Survey Center.
That means they can quickly expand, with a density large enough to dislodge invertebrates in the competition for food and living space.
Cummings said: 'It is difficult to control the development of an animal when it has been introduced into the local habitat. When each lotus snail has the ability to produce large quantities of embryos without a partner, we are actually having a problem. '
Rochelle Sturtevant, an ecologist at the Great Lakes Environmental Research Laboratory - the National Oceanic and Atmospheric Administration in Ann Arbor, Mich., Said scientists do not know if the snail will grow. how strong was it in Lake Michigan, but it was in Lake Ontario since the early 1990s and lived in large numbers there as well as Lake Superior or Erie.
Snails originated in New Zealand but are now found in some western states and in all the Great Lakes except Lake Huron. They move in the water compartments of the ships, and when they enter the lake or stream, they cling to the canoe, even the clothes of the people.
Sturtevant said: 'When they get into streams in the western region, they create a lot of problems. They occupy the living space of native creatures'.
Many invasive species have been introduced into the Great Lakes system. The zebra mussel is a threat to the 4 billion-dollar-a-year fishing area, they eat algae, the lowest level in the lakes' food chain.
Some invasive species create other living conditions for other species, Sturtevant said. Goby, an aggressive fish originating from Eurasia, thrives in the Great Lakes because they eat zebra mussels.
According to Sturtevant, they are just a handful of at least 186 invasive species in lakes.
Environmental organizations specifically condemned the role of ships in bringing creatures like mussels into the system of lakes.
Vessels that do not carry cargo often fill the water compartments to have a stable movement on the sea, then discharge those water tanks when docking. Water compartments often carry several species, from microorganisms to mussels and fish.
The US Environmental Protection Agency (EPA) has introduced a plan this past summer; That is to ask the boat to discharge the water tank 200 miles away from the shore. However, cargo ships are exempt.
However, environmental organizations criticized EPA's plan.
Joel Brammeier, vice president of the Great Lakes System Alliance, said: 'I can summarize with three words: zero. This plan doesn't change anything. '
The maritime industry, including the Great Lake Maritime Association, supports the idea of treating water chambers to remove invasive species. However, a maritime official said while the water treatment is still being studied, so far there is no possible form of the idea.