Partnership focuses on food web disruption

One way to address these complex issues is to bring scientists together. Michigan Sea Grant and the Great Lakes Sea Grant Network are part of a new Partnership on Food Web Disruption formed to look specifically at the effects of exotic species in the Great Lakes. Partners also include the Great Lakes Fishery Trust and the Great Lakes Fishery Commission. The partnership has two purposes: to sponsor research and to coordinate the interaction of researchers, partly by hosting annual workshops. The Whitefish-Diporeia Workshop is an example of such an activity.

"The idea is that you can minimize redundant research and get researchers working together," says Doran Mason, who serves as co-coordinator of the partnership. "The hope is that over time we can reach conclusions to applied questions that continue to define the direction of research."

The partnership focuses on four exotic species: zebra mussels, quagga mussels (which now outnumber zebra mussels in some locations), and two exotic water fleas: the spiny water flea (Bythotrephes cederstroemi) and the fish hook flea (Cercopagis pengoi). These species entered the Great Lakes within the last two decades, most likely arriving in the ballast of transoceanic freighters.

These four exotic invertebrates have claimed critical niches in the "lower food web," explains Mason, along with native zooplankton and other species that provide food for fish. "To understand how food webs affect fish, you have to know who's eating what and how much at these lower trophic levels," says Mason.

Deciphering the impacts of exotic species is a challenge in itself. Yet scientists must also consider the relative impact of other potential sources of food web disruption — from contaminants to climate change. "These are some of the complexities that we're trying to tease out," says Mason. "We need to combine people's abilities and skills to address these issues."