Publication Abstract

Ecosystem Approach to Management for the Northern Gulf of Mexico

McAnally, W. H. (2012). Ecosystem Approach to Management for the Northern Gulf of Mexico. Northern Gulf Institute Ecosystem Team. Stennis Space Center, MS: Northern Gulf Institute. 146.


An Integrated Ecosystem Assessment (IEA) of selected Gulf of Mexico ecosystems was implemented as part of an overall Ecosystem Approach to Management (EAM) effort by the National Oceanic and Atmospheric Administration. The work described here had the following objectives: a. Develop indicators that will define ecosystem “States” for previously initiated Integrated Ecosystem Assessments (IEA) of Perdido Bay, Florida; Mississippi Sound, Mississippi; Barataria Basin, Louisiana; and Galveston Bay, Texas; b. Produce a model framework to link State indicators to Drivers and Pressures; and c. Create a prototype system for the northern Gulf that incorporates findings of these IEA. The systems approach to resource management is defined here as: Managing resources holistically -- with the knowledge that the human ecosystem includes a variety of components that interact with each other individually and globally through processes, behaviors, and feedback mechanisms which must be elucidated in order to describe the effects of external forces and internal actions. Integrated Ecosystem Assessment (IEA) is “syntheses and quantitative analysis of information on relevant physical, chemical, ecological, and human processes in relation to specified ecosystem management objectives” and begins with the identification of a critical management or policy question which helps shape and inform ecosystem management. IEA employs a Drivers-Pressures-States-Impacts-Responses (DPSIR) framework for scoping the ecosystem assessment process and setting management goals. However, the word “Impacts” has negative connotations that may inhibit its applications to some ecosystem effects. For that reason, some practitioners replace “Impacts” in the DPSIR framework with “Ecosystem Services”, producing the acronym DPSER. The work presented here employs conceptual and numerical models of physical and ecosystem processes and establishes a risk framework of interpreting findings. Ecosystem Risk is defined as a measure of the probability and the magnitude of ecosystem effects. The effects can be ecosystem services preserved, gained, or lost. It also employs Sulis, a natural resource assessment system, as an architecture and a software framework. Development of an ecosystem model with food web and fisheries components was begun. Four systems are examined here – Galveston Bay, Texas; Barataria Basin, Louisiana; Mississippi Sound in Louisiana, Mississippi, and Alabama, and Perdido Bay, Florida. They represent a variety of northern Gulf of Mexico estuarine ecosystems over a rather narrow range of latitude, thus offering ample opportunities for contrast and comparison. Three Driver categories – Hydrologic Modification, Climate, and Human-Related Processes – and 13 Pressures have been identified that are pertinent to at least one of the four systems. Salient commonalities are that (1) Human-Related Processes dominate Drivers for the region, with Local Population Size and Tourism/Recreation cited for all systems and (2) five Pressures manifest those drivers: increased fishing effort, increased urban/coastal development, increased boat traffic, increased nutrients, and increased pollution. Nearly equal distributions of Pressures were identified at different scales, ranging from individual lagoons to entire estuaries, but substantial dissimilarities in at least some physical processes suggests that while management measures may be similar at multiple scales, evaluation of the system’s behavior in response to those measures may not be. For example, total dissolved nitrogen (TDN) concentrations were always higher within each of the individual Perdido Bay lagoons than in the surrounding Bay. These results suggest that the assessment step should include both the smaller scale features and the overall system. Human-Related Processes is the most prevalent IEA Driver category, affecting all four systems. Five related Pressures – Increased Fishing Effort, Urban/Coastal Development, Boat Traffic, Nutrients, and Pollution are common to all four systems. Human-related pressures are fishing effort, urban and coastal development, boat traffic, eutrophication and chemical pollution. Habitat modification or loss is the most common Impact associated with the four-system Drivers-Pressures-States, followed by Lack of support for responses and Change/loss of native species. Other impacts, such as Increased storm surge and Eutrophication, tended to be applicable to one or two systems instead of all four. Primary Ecosystem Services affected by the impacts, in decreasing order of occurrence, for the four systems are Habitat Formation, Food, and Educational. As the size of coastal systems increase (for instance when we move from small lagoons to large estuaries), or as we move from the coastal environment to offshore pelagic environments, the relative importance of human-generated stressors is reduced, with natural stressors (climate processes) becoming more important. The work described here demonstrates that: • The IEA/EAM framework based on the DPSIR/DPSER process is a valid approach to identify, prioritize and manage natural and human-induced stressors in Gulf of Mexico systems. Application of this approach to four systems in the Gulf of Mexico that range widely in environmental, societal and economic characteristics shows that this approach is comprehensive and adaptable to the whole suite of natural-human systems in the Gulf of Mexico. • The Sulis Community Ecosystem Models and Informatics Services can be used for performing Integrated Ecosystem Assessments, including the framework for evaluation of management responses including risk assessment. Uncertainty and risk can be successfully addressed by extending well-established practices from the physical sciences to ecosystem sciences and modeling. • The TroSim ecosystem model will provide a management assessment tool for Mississippi Sound. • The Gulf of Mexico offers an excellent domain in which to develop, evaluate and validate strategies for environmentally and economically-sustainable development and exploitation. These resource management strategies can then be applied to allow for a vibrant economy combined with sustained environmental health. Completing the IEA/EAM framework in the Gulf of Mexico will allow this management strategy development to be accomplished.