It's not much to look at. In fact, it's impossible to see without a microscope.
But for the first time in a decade, an exotic aquatic species has been found in the Great Lakes. That makes 185 or 186 non-native species, depending on who's counting, now established in the basin. Some, including the lamprey and alewife, migrated up the St. Lawrence Seaway, but most, including the zebra mussel as well as this latest, probably were introduced via ballast water from ocean-going ships.
Thermocyclops crassus, a type of zooplankton, was discovered in water samples taken from Lake Erie by limnology technician Joe Connolly of Cornell University.
“It’s kind of like looking for a needle in a haystack,” Connolly said. “I didn’t know what it was, but I knew it wasn’t something we’d seen before.”
He found both male and female specimens in low numbers, but enough to say that an established population exists of the invertebrate that is native to Europe, Asia, and Australia. Officials from both the U.S. and Canada have planned more sampling to determine how widespread this new invader is and what its impact may be.
“We don’t know enough yet about what this species could or could not do in the Great Lakes,” said Elizabeth Hinchey Malloy, an environmental scientist with the U.S. Environmental Protection Agency.
Size isn't an indicator of impact, as the zebra mussel, a fingernail-sized shellfish, and the round goby, a small bottom-dwelling fish, have proven.
Confirmed in 2006, the bloody red shrimp was the last previously discovered invader. It now swarms in excess of 135 individuals per square foot.
"The impact of this species on the Great Lakes is yet unknown, but based on its history of invasion across Europe, significant impacts are possible," said Wisconsin Sea Grant Institute. "The bloody red shrimp is an omnivore. Its diet includes waterfleas and algae. They may compete with young fish, while providing food for larger fish. The invasion of this species in some European reservoirs has been documented to accelerate silica cycling, resulting in blooms of diatoms and, in some cases, plating out of silica onto pipes."