INVASIVE SPECIES – KILLER SHRIMP

Unless you’re allergic to shrimp, I bet you’ve never thought of shrimp as killers, and especially not in the Great Lakes.
Killer shrimp (Dikerogammarus villosus) was added to the Michigan Department of Natural Resources banned species list in November 2014. They have not yet been found in Michigan; however there are many worries that they will begin invading Lake Michigan and work their way through the Great Lakes. Killer shrimp are native to eastern Europe, but are considered invasive in western Europe.

These tiny killers are an inch long full grown and, according to Nick Popoff of the DNR, “have really big mouth and claws, and they literally shred their prey. They are very aggressive in any of the ecosystems that they get into”. Killer shrimp will eat any invertebrate their size or smaller, including other shrimp species. These shrimp in our lakes would highly threaten the entire aquatic food chain. Since they feed on invertebrates they take food away from small fish causing a decrease in population which then limits the food source of larger fish, again causing a decrease in population.
Killer shrimp are believed to be transported into the US by means of ballast water in ships coming from Europe. Ships take on water to help stabilize them when they unload cargo, passengers, waste, etc.; the water is then released from the ballast tank into the body of water. These shrimp can survive varying water temperatures, pH’s, and salinities so they can make it in the ship ballast tank for long periods of time. It is estimated that they can survive approximately 24 hours in ocean salt water. Ballast water is also responsible for the introduction of zebra mussels and gobies into the Great Lakes; ballast water protocols are now in place to help prevent such introductions.