Palearctic predator invades North American Great Lakes

Area of Science:

• Ecology
• Invasive Species Biology
• Freshwater Ecology

Background:

• Bythotrephes cederstroemii, a predatory freshwater zooplankter, was first identified in the Laurentian Great Lakes in December 1984.
• This species, previously confined to the Palearctic region, has expanded its range significantly since its North American debut.

Purpose of the Study:

• To document the invasion and spread of Bythotrephes cederstroemii in the Laurentian Great Lakes.
• To investigate the habitat preferences and potential ecological impacts of this invasive species.

Main Methods:

• Field observations and sampling to track species distribution and abundance.
• Analysis of habitat characteristics in relation to Bythotrephes presence.

Main Results:

• Bythotrephes cederstroemii rapidly colonized Lakes Huron, Erie, Ontario, and southern Lake Michigan between 1984 and 1986.
• The species showed a preference for offshore regions and avoided habitats occupied by established glacio-marine relict species.
• Abundance increased dramatically, particularly in Lake Michigan's offshore areas.

Conclusions:

• Bythotrephes cederstroemii is aggressively invading the Laurentian Great Lakes ecosystem.
• As a voracious predator, its establishment may lead to significant alterations in native zooplankton communities.
• The species is likely to become a permanent component of Nearctic zooplankton communities.