Hemimysis anomala, Shrimp
Eight years ago, two researchers at a Canadian university predicted the half-inch, bright orange Hemimysis anomala was a likely candidate to follow other Caspian Sea region invaders such as the zebra mussel into the Great Lakes, if more wasn't done to stop the discharge of contaminated ballast water from oceangoing freighters traveling up the St. Lawrence Seaway. The shrimp has now turned up near Muskegon, Mich.
Anthony Ricciardi of McGill University in Montreal, one of the scientists who predicted the shrimp's arrival, describes it as another sign of an "ecological takeover" of the Great Lakes by species native to the Black and Caspian Sea regions.
The dominant mollusk in most parts of the Great Lakes is now the zebra and quagga mussel, the dominant zooplankton is the fishhook water flea. The bottom-dwelling fish are becoming more and more dominated by the round goby and ruffe.
This new species of shrimp is likely to turn up in other areas of the Great Lakes, because the Muskegon port typically receives very little overseas traffic. This means the initial invasion likely happened somewhere else in the lakes.
Juveniles and mature females have been found in the channel connecting Muskegon Lake to Lake Michigan, indicating that the species is likely reproducing in the Great Lakes. If so, that apparently brings the number of Great Lakes invaders to 183, and it probably won't be long until No. 184 is found; for the past three decades a new exotic species has been discovered in the Great Lakes, on average, about every 6½ months.
December 22, 2006 6:43 AM | Category: Invasive Species