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Ecological Classification - CMECS


The Coastal and Marine Ecological Classification Standard (CMECS) is a structured catalog of ecological terms that also provides a framework for interpreting, classifying, and inter-relating observational data from all types of sensors and platforms. The CMECS vocabulary describes coastal and marine environments from the head of tide in estuaries to the depths of the oceans and Great Lakes, and offers an umbrella under which a national coastal and marine ecological classification can grow and evolve.

Endorsed by the FGDC in 2012, CMECS builds upon approaches from published national, regional, and local habitat classification procedures. As an FGDC standard, federally funded projects working with environmental data in marine settings should use CMECS as their primary classification system or include CMECS attributes for their data.

CMECS Partnerships

CMECS was developed, tested, and distributed for peer review over a period of several years by a core group with members from the NOAA Office for Coastal Management, NOAA Office of Habitat Conservation, U.S. Environmental Protection Agency, U.S. Geological Survey, and NatureServe working with hundreds of scientists and coastal managers. The collaboration continues in the CMECS Implementation Group (IG), which

  • Promotes and provides guidance for its use
  • Coordinates standard maintenance and updates
  • Facilitates working relationships between CMECS users

CMECS Partnerships

The six elements of CMECS represent the different aspects of the seascape, starting with the broadest systems and narrowing to the most detailed physical and biological features associated with a specific habitat type.

The foundation of CMECS are ecological units. A unit is any defined entity occurring at any level in the classification hierarchy. Individual units are organized within the four thematic habitat components for water column, biotic, substrate, and geoform data.

Biogeographic and aquatic settings are differentiated by features influencing the large-scale distribution of organisms, and by salinity, tidal zone, and proximity to the coast. (marine, estuarine, and lacustrine).

Components and settings can be used independently of each other or in combination depending on the observation methods used and research objectives.

Modifiers are additional terms that can be used on a case-by-case basis where CMECS does not provide the necessary level of description for the data. Users can define and add their own additional modifiers as needed. This option for customization provides flexibility so that CMECS can meet the needs of individual projects.

A biotope is a classification that combines biotic and abiotic features to fully characterize the unique combination of environmental variables and associated species that make up a particular habitat type for a specific area.

Select the images below to see how each site might be classified using the different settings, components, and modifiers of the CMECS system.
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Share your classification by emailing the CMECS Implementation Group at

The resources in this section provide guidance for applying CMECS in fieldwork and mapping. They are not requirements, and may be modified or retired according to changes in technology and the standard itself.

Applying CMECS to Data

Proposed CMECS Data Structure – A short outline of how CMECS data could be organized in an ESRI file geodatabase structure.

Coding Approach and Code Set – Spreadsheets with the code set for the entire CMECS system and a short document explaining how the codes can be applied as attributes for observations and mapping.

Classifiers Document – Document that presents the physical, chemical, and biological characteristics necessary to assign CMECS unit labels to data. This is of value to those collecting source data that will later be used to develop CMECS habitat maps.

Nomenclature Document – Several examples of how CMECS unit names from several components can be compiled into terminology for CMECS-derived units.

CMECS Concept Map – A graphical representation of the CMECS component framework and hierarchical structure. Useful for understanding how the components relate to each other and which ones might be appropriate for specific projects.

Crosswalking Other Classifications to CMECS

Crosswalking is the process of converting attributes or data from one classification scheme to another. This may be necessary when integrating legacy data into a new system, or when assembling disparate data sets into a larger framework.

Conceptual crosswalks describe the definitional relationships between units in two classification systems. Data crosswalks involve re-attribution of digital spatial data. Data crosswalks build on the conceptual relationships but also are influenced by spatial scale and observation methods.

Appendix H of the CMECS 2012 document describes best practices for crosswalking data to CMECS

Conceptual crosswalks from commonly used classification systems to CMECS:


CMECS Crosswalk Tool. A downloadable tabular analysis tool developed by the NOAA Office of Coastal Management that translates existing spatial benthic habitat data sets into CMECS compliant feature layers. The tool runs in Esri ArcMap (desktop) software.

Individual projects implement CMECS in different ways to meet specific mapping and research needs, resulting in various approaches to utilizing the framework.

The CMECS in Action interactive map shows the locations of a growing collection of projects across U.S estuarine, marine, and Great Lakes waters. The map includes information about the project, the settings and components used, and links to project resources and data where available.

CMECS Dynamic Standard Process
CMECS was designed as a dynamic content standard that relies on continual user engagement to keep up with advances in scientific knowledge, technology, and the needs of the coastal management communities. The Dynamic Standard Process (DSP), developed and overseen by the CMECS Implementation Group, is a means to gather feedback and recommendations from users for improvements to CMECS. While many aspects of this process are still being refined, the DSP has, and will continue to have, these standard characteristics:
  • Clear criteria and requirements for proposing and evaluating a change to CMECS
  • The involvement of subject-matter experts when needed to ensure scientific validity of any change
  • Different levels of review depending on the scale of the proposed change
  • Feedback loops to proposers and reviewers
  • The ability to track and maintain lineage between old and new versions of CMECS
  • A requirement to publicize adopted changes and new implementation guidance