Principle Investigators:  Dr. Brian Shuter, Ontario Ministry of Natural Resources,  and Doran Mason, Purdue University

Project Dates:  January 2000 - December 2003

Total Costs:  CAN $128,150.00 (over four years)

Research Objectives:

First, identify the proximate mechanisms and processes through which recently introduced invertebrates disrupt food webs. Second, determine how these mechanisms are affected by lake size and morphometry, climate, latitude, and community composition. Third, forecast how food webs in both the lower and upper Great Lakes will look when invertebrate colonization is complete.

Scientific Challenges:

1. An invasion by exotics and the consequent species succession is driven by changes in the relative competitive abilities and predator/prey relationships of native and invading organisms. Great Lakes environments are highly seasonal, and in such environments habitat overlap among competitors and predators is a dynamic quantity that varies temporally and spatially throughout the year, strongly reflecting the patchy distributions of individual species. These distributions, in turn, reflect the responses of individual organisms to significant limnological events (e.g., annual stratification cycle, and seiches), the magnitude and frequency of which are shaped by the size and morphometry of the lake itself. In addition, the patchiness of these distributions will greatly affect the efficiency of energy transfer from prey to predator (e,g., McNaught 1980, Mann and Lazier 1996, Letcher and Rice 1977). An explicit representation of such within-year processes is necessary to clearly model the mechanisms that drive changes in food webs and the consequent shifts in the dominance of different fish species.
2. The spatial and temporal scales necessary to effectively represent the invasion process and its impact on existing food webs must be determined empirically. Current Great Lakes fish community models are designed to operate at temporal and spatial scales that are too coarse to adequately represent such processes. They will need to be extended/modified to describe processes operating at finer spatial and temporal scales.
3. More complete empirical descriptions of the invasion process, as it continues in both the lower and upper Great lakes, is necessary to develop procedures for forecasting impacts on the upper lakes. The geographical scale of the Great Lakes is so large that extensive new data collections with traditional sampling gear is extremely expensive. Hence, significant research effort will be required to develop/extend non-traditional data collection techniques (e,g., sidescan sonar, fisheries acoustics, optical plankton sensors, satellite/aerial remote sensing, fixed buoys) to permit economically feasible and effective study of invasion processes at these very large geographic scales.
4. Because lake scale and morphometry likely play a critical role in determining the extent and rate of an invasion, comparative studies of the invasion process in several lakes would be particularly valuable in developing useful techniques for forecasting impacts in the upper lakes.

Approach:

The purpose of this research task is to provide a process for 1) developing a concept paper that identifies lines of research necessary for meeting the research objectives stated above, 2) securing input to the concept paper from the broader research community, 3) exchanging ideas and information related to the research, 4) reporting progress in meeting research objectives, and 5) recommending changes in research direction. The principal investigators will report to the Board of Technical Experts, who with its partners will, following acceptance of the concept paper, solicit proposals to undertake the identified research needs. A process for acceptance and solicitation by the Board and its partners remains to be formalized. Thus, the proximate goals of the task are to define research direction and to provide for research coordination; they are not to undertake the research itself.

Concept Paper

1. The PIs will begin by undertaking a focused and comprehensive review of the current state of scientific knowledge regarding the impacts of invertebrate invasions on the lower Great Lakes with a particular focus on fishery impacts. This review will piggy-back on existing initiatives such as Lake Erie at the Millennium and IAGLR modeling summits. The objectives of this review are to

    

   • list the potential impacts, especially fish-community impacts, of the invertebrate invasions of Lake Ontario and Lake Erie,
   • evaluate each potential impact as follows:

   1. available evidence clearly demonstrates occurrence of impact,

   2. available evidence suggests occurrence of impact, and

   3. available evidence suggests impact not occurring.

    

   • identify promising lines of research needed to meet overall objectives of the task.
2. This review will form the core of the concept paper to be discussed at the first workshop. A draft version of the concept paper will be ready for distribution to workshop attendees in early September 2000. The first workshop will be held by early October and the final version of the concept paper will be distributed to BOTE by mid-October.

Annual Coordination Workshops

The PI’s will organize annual invitational workshops. The purpose of the first workshop will be to critique and finalize the concept paper described above. Later workshops will examine and critique progress of funded research projects and will identify promising new research areas. These workshops will include

• presentations by current grant holders
• presentations by invited experts, currently not holding grants, but working in related areas
• a synthesis session where presenters critically examine the current state of knowledge, recommend adjustments to ongoing projects, and identify new projects worthy of funding.

A primary objective of the synthesis will be to produce a prioritized list of those research projects that the participants believe would best meet the overall objectives of the task. This structure raises the possibility that grantees will be required to change project direction prior to project completion. To accommodate this possibility, the funding agreements developed by the partners should permit current grant holders to suggest changes in their proposals while work is still in progress.

Support Work

A research associate will be engaged to support the PI’s in several ways:

· assist with preparation of the concept paper

· assist with organization of annual workshops and preparation of workshop reports

· carry out focused research on how to effectively and efficiently construct management models of invertebrate invasions that represent events occurring at a wide range of spatial and temporal scales.

At the modelling summit held at the 1999 IAGLR meeting, several authors recognized the difficulties inherent in trying to describe, in a single management model, lower trophic level events (short time scale, e.g. hours; fine spatial scale, e.g., meters) and top-predator behaviour (long time scale, e.g., years; coarse spatial scale, e.g., whole lake). The brute force approach to this problem is operationally complex and computationally immense. A significant literature is now in place (e.g., Tilman and Kareiva 1997, Bascompte and Sole 1998) describing simpler approaches. The research associate will undertake a Ph. D. program at the University of Toronto (supervised by PI Shuter) aimed at developing simpler ways of dealing with scaling problems in Great Lakes invasion models. Existing models of Lake Erie and Lake Ontario would be used explicitly in the work. The research would be directed at identifying and developing approaches that would be implemented in the predictive management models that will be developed under the overall mandate of the task.