The Chesapeake Atlantis Model (CAM), currently under development, is based on the Atlantis software developed by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO). This model is an approach for conducting formal management strategy evaluation—a simulation that accounts for tradeoffs in performance across a range of management objectives. It provides the decisionmaker with information on which to base a rational decision, given the decisionmaker’s objectives, preferences, and attitude concerning risk; it does not prescribe an optimal strategy or decision.

Differing from simpler models that incorporate only multiple species or only trophic interactions, CAM is a true ecosystem-based model for the Bay. It incorporates spatially explicit information about the biological, geochemical, and physical forcings of the Bay and its tributaries, the effects of different user groups, and dynamically tracks the interaction of these factors over time. As a management strategy evaluation, it also simulates the important processes of assessment, management and compliance.

Applications of the Atlantis Model

Previous applications of the Atlantis modeling approach have been undertaken both domestically and abroad. Ecosystems modeled vary considerably, as have the insights gained by resource managers. Recent efforts by NOAA include applications on both the West and East Coasts. On the West Coast, Atlantis has been applied to model the California Current ecosystem (Brand et al., 2007). This work has proven useful for testing ecological indicators, setting federal (both sanctuary and fishery council) management for marine protected areas in an ecosystem context, and evaluating effects of individual transferable quotas. 

On the East Coast, the approach has been most recently applied to evaluate economic pressures, effort allocation, and gear choice with a goal of sustainable fisheries in a context of climate change (Link et al., in review). That group has found the modeling approach useful to gain insights into the consequences and tradeoffs for different monitoring, assessment and management scenarios. In Australia, where the approach was first developed and applied, Atlantis has had the most extensive application. In Southeast Australia, where the ecosystem of Port Phillip Bay was examined, model simulations have led to several important general conclusions for that system, and potentially for other large estuarine bays as well. Fulton and Smith (2004) conclude that eutrophication can be more important to the health of a bay ecosystem than fishing; a few key species can capture the major ecosystem impacts of alternative management strategies; ecosystem models identify potential impacts that single-species models are unable to identify, and policies that focus on only the higher trophic levels can fail to achieve sensible ecosystem objectives.

How Atlantis Can Benefit the Bay

There are a variety of important benefits to developing the Atlantis model for the Chesapeake Bay. Such a modeling approach allows exploration of the ecosystem effects of environmental changes, policy options and management strategies. Arguably, the most important benefit of the Atlantis approach is that it lends itself to the exploration of a wide variety of different scenarios of interest to management. Once the CAM model is fully developed, a wide variety of topical questions can potentially be explored. For instance, what will be the likely ecosystem effects of eel grass loss or loss/gain of marsh habitat? Of a larger/smaller population of striped bass, oyster, menhaden, or blue crab? Of increasing/decreasing nutrient input, or of increasing population size along the coasts of the Chesapeake? These types of questions can be explored with the Atlantis approach, and importantly, such questions can be explored by area, because Atlantis is a spatially explicit modeling approach. Underlying the usefulness of model forecasts is the availability of pertinent data; consequently, another important use of the CAM will be to help identify and prioritize the most critical needs for research within the Chesapeake Bay ecosystem.

While development of CAM is complex, NOAA modelers have a head start as it will build on the results of the Chesapeake Bay Fisheries Ecosystem Model. Results from CAM should be extremely useful for managing the natural resources of the Chesapeake Bay. CAM simulations will inform decisionmakers of the probable outcomes of implementing different management strategies in an ecosystem-based framework.

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