| Coastal Habitat Restoration Model for Submerged Aquatic Vegetation
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| Conch in seagrass. Courtesy Heather Dine, Florida Keys NMS |
Ecosystem Restoration Overview
Ecosystem restoration is generally defined as returning a system that has been altered, degraded, or destroyed to a state that closely mimics pre-disturbance conditions. The term "restoration" can be used to describe many different approaches, and is a complex process that is being performed on numerous scales throughout the United States and abroad to combat damage that has been inflicted upon coastal ecosystems. Gulf of Mexico coastal ecosystems are vulnerable to anthropogenic effects ranging from coastal development to watershed inputs. Many organizations are working throughout the Gulf to restore ecosystems that have been changed over time to help rebuild ecosystem functions and services. See <<Primer on Ecosystem Restoration (pdf)>> for more information on ecosystem restoration.
Addressing Uncertainty in Coastal Habitat Restoration
Steps for Conducting Coastal Habitat Restoration Projects
Our capacity to successfully restore or enhance coastal habitats depends on our ability to understand the relationships that occur within them. Recent coastal habitat restoration projects have used conceptual models to document these relationships (Ogden et al. 2005, Rudnick et al. 2005). To facilitate our understanding of coastal habitats in the Gulf of Mexico, GoMRC has developed an ecological conceptual model for submerged aquatic vegetation (SAV), including seagrasses, that occur throughout the Gulf of Mexico.
GoMRC's Conceptual Model forSAV
GoMRC's conceptual model for SAV enables users to explore ecosystem elements influencing SAV. The model provides scientific-based overview of relationships and processes that transpire within coastal SAV habitats, and offer guidance for future restoration efforts. Components of the model have been classified into six major categories: stressors, controlling factors, structures (SAV species), processes, functions, and social values. The table below provides definitions of these major categories and information on individual components of the conceptual model.
Stressors – Ecosystem stressors are "out of the ordinary" natural and unnatural inputs to the system that disturb the controlling factors, structure, and processes in the ecosystem. Stressors produce potentially large-scale effects on the natural spatial and temporal dynamics of the system. Examples: storm events, dredging, filling.
Controlling Factors – Controlling factors are the basic physical and chemical conditions that construct and influence the structure of the ecosystem. Examples: light, salinity, temperature.
Structure – Ecosystem structures are the major habitat units in the system. Fully developed and functioning structures are self-maintaining, resilient, and sustainable. There are many possible structures that constitute a coastal habitat ecosystem including barrier islands, coral reefs, and salt marshes. This model focuses on SAV as the primary structure of interest.
Processes – Ecosystem processes are a series of biological, chemical, or physical steps or operations which have a given result or product in the ecosystem. Processes form the fundamental conditions and outputs of the ecosystem. Examples: filtration, wave dampening, carbon sequestration.
Functions – Ecosystem functions are the primary "products" generated by the ecosystem in addition to providing basic ecosystem sustainability. Examples: storm surge protection, water quality maintenance.
Values – Ecosystem values are the services provided by the system specifically in support of human needs. Examples: clean water, recreation, shoreline protection. |
The web-based user interface for the ecological conceptual model is the Conceptual Model Explorer (CME). The CME highlights relationships among stressors, controlling factors, and habitat structures, and gives users the ability to modify the model to suit their individual needs.
Addressing Uncertainty in Coastal Habitat Restoration
Restoration practitioners are frequently challenged by uncertainties in coastal habitats. Uncertainty may stem from an incomplete understanding of an event, the result of a process, or data and may be associated with two sources: (1) inherent variability or (2) knowledge uncertainty. Inherent variability (inconsistency of processes) is a commonplace unpredictability in ecosystems (Diefenderfer et al. 2005). Uncertainties related to inherent variability in a coastal habitat restoration context may be associated with processes that are assumed to be random in space (soil properties), or time (stream flow) (Diefenderfer et al. 2005). Conversely, knowledge uncertainty relates to the poor understanding of events and processes or from insufficient data to draw conclusions (Diefenderfer et al. 2005). Examples of both types of uncertainty outlined in Thom et al. (2005) include lack of information on existing site conditions and/or historical site conditions; poor understanding of ecosystem controlling factors, funding, or climate variability; offsite issues affecting habitat-forming processes; and social uncertainties.
Even though uncertainty is inherent in coastal habitat restoration, it may be reduced through careful project planning. In a review of programs and projects that have put into practice principles of adaptive management the most successful have employed the following practices: systematic data collection, controlled manipulations, data analysis, and selection of action alternatives based on a careful evaluation of project data (Thom et al. 2005). Uncertainty can be reduced, or at a minimum can be identified by systematic restoration planning, examining results of similar projects, and through adoption and implementation of adaptive management principles.
To gain a better understanding of restoration site processes and functions, conceptual models along with tools such as aerial imagery, map viewers, and data searches can provide core knowledge of the system state. GoMRC's models and tools can better equip resource managers to make informed decisions when uncertainty arises during restoration.
Steps for Conducting Coastal Habitat Restoration Projects*
1. Project Planning: charting the course of action – Restoration project planning begins with a vision or an idea of the desired target state of the ecosystem based on ecological or biological requirements and a path forward to achieve it. The vision can be transformed into the main goal(s) of the project. Development of planning objectives or a strategy of how the goals will be achieved is the next step in the planning process. Another important piece is the development of a conceptual model which is used as an informative tool that provides a level of understanding of a particular habitat that will undergo restoration. An additional consideration is the development of performance criteria which are quantifiable or observable measurements used to track the progress of a system in meeting project goals. Other considerations in project planning are site selection, costing, contingency planning and development of a monitoring program.
2. Project Implementation – Once construction is initiated, it is essential that a restoration planner be involved in the process to ensure that project needs and goals are being met and that the right people, including engineers and contractors, are providing their expertise to project tasks. Site monitoring after construction begins is critical to conform to project goals, plans, and designs to ensure they are implemented according to specifications, and that construction itself is not negatively impacting surrounding habitats.
3. Performance Assessment – After construction is completed a monitoring program is initiated to assess restoration site performance. It provides feedback on how the site is developing over time with respect to performance criteria by physically measuring environmental parameters outlined in the planning stage.
4. Adaptive Management – Adaptively managing a restoration site provides the opportunity to make adjustments to the site if the restoration is not following its planned trajectory of development. Information guided by site monitoring provides restoration planners with data on how well the site is meeting goals and performance criteria. Restoration managers are faced with three options: taking no action and allowing the site to develop without physical aid, maintaining the system, or modifying of project goals and taking appropriate action to meet the revised goals.
5. Dissemination of Results – Results of a coastal ecosystem restoration project should be provided to entities that have a stake or interest in the progress and outcome of a restoration project. Results can be disseminated through project reports, presentations, uploading information to various restoration websites, publication in a peer-reviewed journal, technical meetings, scientific conferences, and workshops.
*Modified from: Diefenderfer, H.L., Thom, R.M., and Adkins, J.E. 2003. Systematic approach to coastal ecosystem restoration. Battelle Report No. PNWD-3237. Prepared for National Oceanic and Atmospheric Administration, Coastal Services Center, September, 2003.
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