The Great Lakes now have a total of 180 documented foreign species now that scientists have observed two new exotic species, both about the size of a flea. They both have been found in low abundance, and scientists have no evidence so far of serious negative side-effects on native zooplankton species. For that reason, they are not yet being referred to as “invasive,” a term which is typically reserved for species with negative impact. These are the third and fourth non-native zooplankton species discovered in the Great Lakes in the past three years.More