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GLERL NONINDIGENOUS SPECIES RESEARCH PROGRAM
General Background
The Nonindigenous Species program at GLERL involves projects aimed at understanding the ecological ramifications of invasives currently established and also the prevention of new introductions. A brief description of each current project in the program follows.
One research project at GLERL is examining the role of zebra mussels in promoting nuisance blooms of the potentially toxic blue-green alga Microcystis. Part of this work has examined the roles of the mussels' selective filtering and nutrient excretion in promoting blooms. Preliminary findings suggest that mussel selective filtration may promote Microcystis dominance, but a source of Phosphorus (P) is needed to explain the blooms. The mussels may be fostering algal blooms by regenerating P that had already been deposited in deep sediments.
High densities, widespread distribution, and high filtering rates enable zebra mussels to filter large volumes of water and have the capacity to decrease algal biomass, significantly altering the ecosystem. In Lake Michigan, Dreissenid (zebra) mussels have modified habitats for benthos and fishes and fostered growth and proliferation of non-indigenous species, such as the round goby and a Black Sea amphipod, Echinogammarus. Field work involving sidescan sonar and acoustic bottom classification will document the coverage of mussels on the lake bottom and be used to model and predict future sites of high colonization.
The Great Lakes have recently undergone a second wave of species invasions dominated by zebra mussels (Dreissena polymorpha), quagga mussels (D. bugensis), and two exotic invertebrates - Bythotrephes cederstroemi and Cercopagis pengoi. Unlike previous fish invasions (e.g., sea lamprey and alewife), these invertebrates inserted themselves in the lower trophic levels, disrupting the food web with potentially serious consequences for fish communities. Two GLERL projects are examining various facets of this new wave of invaders. One is studying recent changes in the pelagic food web of the southern basin of Lake Michigan to determine whether these changes were caused by nonindigenous species. Another project will use network analysis to quantify the change in food web structures and flows and the resulting impacts on fish communities in the Great Lakes as a result of these new invasions.
A new modeling project will seek to build "virtual ecosystems" composed of populations of "digital organisms" to be used as a tool to investigate properties of invasive species and their ensuing effects on ecosystems. Manipulation of this artificial system, which emulates the natural system, will provide opportunities to probe relationships and dependencies, providing insight into the natural system and the problem of invasive species.
Preventing future introductions of nonindigenous species via ballast water is a high regional and national priority and is also under investigation at GLERL. Two potential biocides for disinfecting ballast water, glutaraldehyde and hypochlorite, are the subject of a lab-based project. The aim of this project is to provide the toxicological profile for the potential use of these two materials as ballast water disinfectants. Another project is examining the risk associated with residual ballast water and mud found in most "NOBOB" (NO-Ballast-On-Board) vessels entering the Great Lakes. These residues can contain a wide assortment of plants, animals, and microorganisms, including so-called "resting stages". The same project is also conducting experiments to assess the effectiveness of open-ocean exchange in decreasing the diversity and concentration of live nonindigenous species in ballast water, especially targeting fresh or low-salinity ballast water originating from Europe.
Last updated: 2004-03-25 mbl