Coastal and marine planners and managers are faced with a complex environment in which to make difficult decisions about habitat conservation and resource management. Given this complexity and recognizing the vastness of the marine environment for which the United States has jurisdiction, there is an urgent and increasing need for a national habitat classification approach that can be used to develop strategies for resource management and conservation. To meet this need the National Oceanic and Atmospheric Administration and NatureServe developed the Coastal and Marine Ecological Classification Standard (CMECS), a classification standard that is relevant to all U.S. coastal and marine environments and that can be applied on local, regional and continental scales. The classification provides a structure for synthesizing data so that habitats can be characterized and reported in a standard way, and information can be aggregated and evaluated across the national landscape and seascape. Built on existing classification efforts and informed by a series of technical meetings and workshops, the CMECS standard integrates the current state of knowledge about ecological and habitat classification. The result is an ecosystem-oriented, science-based framework to allow effective identification, monitoring, protection, and restoration of unique biotic assemblages, protected species, critical habitat, and important ecosystem components.
A few of the many potential applications of the classification include:
- Development of a coastal marine biodiversity inventory for North America
- Delineation of regions for Marine Protected Areas and developing guidelines for their management
- Identification of important habitats and critical hotspots for conservation
- Identification of Essential Fish Habitat
- Formation of a scientific basis for the development, implementation and monitoring of ecosystem-based management strategies for coastal systems
Previous versions of CMECS (Madden et al. 2004, Madden et al. 2005) and a precursor (Allee et al 2000) were developed with the input of over 40 coastal and marine habitat experts. CMECS Version III is the product of further refinement with an added emphasis on mapping applications. Most changes in Version III were made to align CMECS with two Federal Geographic Data Committee Standards: 1) the Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al. 1979) the federal standard for classifying and mapping wetland and deepwater habitats, and 2) The U.S. National Vegetation Classification the federal standard for classifying vegetation (Jennings et al., in press, FGDC 2007). The resulting CMECS Version III standard is applicable on spatial scales of less than one square meter to thousands of square kilometers and can be used in littoral, benthic and pelagic zones of estuarine, coastal and open ocean systems.
CMECS Version III has three distinct components each describing a different aspect of the coastal and marine environment. Taken together, these components provide a structured way to organize information about coastal and marine habitats and a standard terminology for describing them. The fundamental component is the Benthic Cover Component (BCC). This hierarchical system describes the geomorphologic, physico-chemical and biological composition of the coastal and marine substrate. The Water Column Component (WCC) describes the structure, patterns, processes and biology of the overlying water column. The Geoform Component (GFC) describes the major geomorphic or structural characteristics of the coast and seafloor at various scales. The flexibility of the CMECS classification standard will support a variety of local and regional applications.
Specifically, the Benthic Cover Component (BCC) classifies geologic and biotic cover of the substrate at different spatial scales and places the associated biology in the context of the physical habitat. This component is organized into a branched hierarchy of seven nested levels which correspond to both functional ecological relationships at progressively smaller map scales. The BCC branches into five Systems at the highest level based on salinity, depth and enclosure and two Subsystems defined by tidal regime (i.e., intertidal or subtidal). Each Subsystem further divides into Classes (e.g. coral reef, aquatic bed) and then Subclasses (e.g. spur and groove reef, rooted vascular vegetation), largely adopting the values in the FGDC wetland classification standard (Cowardin et al. 1979). Groups are defined within the Subclasses based on factors that collectively impact the ecology and biotic composition of the Biotopes. Biotopes represent broad biological associations identified by dominant or diagnostic species that are fixed to the substrate. Modifiers may be used at any level of the hierarchy to separate one unit in the classification from another.
The Water Column Component (WCC) describes the structure, pattern and processes of the water column. While highly variable spatially and temporally, conceptually, the water column can be viewed as being composed of repeating structures and processes that strongly influence the distribution and condition of the biota. This classification component contains nine classifiers which are similar in character to modifiers within the BCC (e.g. depth zone, salinity). In the WCC, however, the classifiers are required for defining the water column classification units while the application of modifiers within the benthic component is optional. The WCC classifiers can be used alone or in combination to describe the structure and composition of the water column the classification of the water column is not strictly hierarchical. The first classifier, System, is the same as that of the BCC and should always be used to put the water column units into the same context as the BCC. Additional classifiers address depth (vertical zonation), structure (upper and lower water column), macrohydroform (e.g., major ocean currents, large coastal fronts) mesohydroform hydrographic features (e.g. waves), biotic cluster and biotope. Because of its dynamic and three-dimensional nature, the water column can be a challenge to map. The WCC is intended to be mapped independently of the other components of the classification standard to provide information on distinct water column ecological units as necessary. However, it can be overlain on the BCC and GFC components to help users understand the vertical component of the marine environment.
The Geoform Component (GFC) describes the structure of the coastline and sea floor at multiple scales. A Geoform is equivalent in concept to a terrestrial landform (e.g., mountain, butte, moraine, etc.) and likewise varies in scale from very large (e.g., seamount, embayment) to very small (e.g., tidepool, ripple). Geoforms shape the large scale seascape in repeatable and predictable ways by providing structure, channeling energy flows, regulating bioenergetics and controlling transfer rates of energy, material and organisms. The morphology of these features controls such processes as water exchange rates and water turnover times, hydrologic transport, energy and nutrient cycling, shelter and exposure, and migration and spawning patterns. The framework for the GFC is based largely on the structure described by Greene et al. (2007), but expands it and re-organizes some options to encompass a larger number of coastal and nearshore features. As with the WCC, the GFC is intended to be mapped as a separate layer from the BCC. When overlain on the BCC, the GFC layer can provide additional insight into how benthic patterns vary with the structure of the substrate. GFC units may also be used independently when information on structure is required to meet the objectives of a given project.