Dr. Ihde is a marine and estuarine fisheries scientist with 20 years of experience working in the Chesapeake Bay system. His main interest is in the application of the best tools and approaches to improve the management of our marine fisheries resources. In the Chesapeake, we have historically been challenged by over-enrichment of the system, habitat loss, and overfishing. More recently, climate change has increasingly been recognized as an additional, critical stressor on the system. Over the last seven years while with the Chesapeake Bay Program (CBP), with the help of a wide range of regional scientists, Dr. Ihde has built and applied an interdisciplinary, whole-system production model known as Atlantis. He uses the approach to forecast the productivity of our living resources in the context of both our restoration efforts, and the multiple, simultaneous stressors affecting the Chesapeake Bay. He is an active member of the CBP's STAC, as well as both the Habitat-Goal Implementation Team and the Fisheries-GIT.
There have been numerous indicators that there has been progress in improving the water quality indicators for the Chesapeake Bay system. Less clear, are the effects of these water quality improvements on the living resources of this system, or the scale of those effects in comparison to other stressors like changing water temperatures in this region. Similarly, the cumulative effects of multiple, simultaneous stressors in combination with the water quality improvements are difficult to estimate, and there are relatively few tools available with which to accomplish this task. One such tool is an"end-to- end" or "full-system" modeling approach called "Atlantis". The Chesapeake Atlantis Model (CAM) is a deterministic, biogeophysical, production simulation model of the Chesapeake system, designed to provide strategic information on the trade-offs of different management choices, e.g., targeted restoration, ongoing habitat loss due to sea level rise and shoreline hardening, water quality improvement, etc. The spatial modelling approach includes a wide range of system features, the most important of which are: physical forcings of heat, salt, and water movement; predator-prey dynamics; bacteria (and plant) mediated nutrient and chemical cycling; and habitats that not only grow (and decline) over time, but that also serve as refuge for prey species. Expected changes in the Chesapeake system are simulated for 50 years into the future; marsh loss, submerged aquatic vegetation loss, TMDL attainment (for nitrogen and sediment loads), along with temperature increase are simulated separately and in combination, to estimate cumulative effects of these multiple factors, and to determine a dominant driver of change for the Chesapeake. Results from this work suggest that the water temperature increases expected for the Chesapeake system will be a very strong driver of productivity change, and that any work on other factors should consider expected temperature increases as well. Applications of CAM to specific Outcomes and Key Actions of the various CBP Workgroups to support the New Bay Agreement (2014) are also discussed.