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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. Learn more in the CMECS one pager and FAQs.

You can also visit the NOAA National Centers for Environmental Information's (NCEI) CMECS site to learn how to submit suggestions for improving CMECS and for up-to-date information about the CMECS maintenance process. The NCEI site also includes the unit's database, the coding system, and the codeset.

CMECS Update News

On April 17, 2022, the Coastal and Marine Ecological Classification Standard (CMECS) Substrate Component Workgroup, an interagency team, convened to review implementation issues with the component that had been identified by the CMECS user community since its publication in 2012, and to develop a set of change proposals to address them. The workgroup held a series of virtual meetings and convened targeted discussions with smaller groups of subject matter experts to tackle specific topics. After many discussions and iterations, the workgroup recommended several substantive improvements that make the Substrate Component easier to use and apply more consistently. The CMECS Implementation Group approved those changes for publication on October 20, 2023.

The CMECS team are writing a workgroup report which will be published as a citable NOAA Technical Memo that documents the update process, provides rationale for the changes, and contains the final version of the Substrate Component units and framework. In the meantime, spreadsheet and thesaurus document versions of the Substrate Component units and framework are available to download from the NOAA National Centers for Environmental Information (NCEI) CMECS GitHub.

CMECS Substrate

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.
Download the Complete Gallery

View sample images for biotic and substrate classification. This is a set of slides presented at GeoTools 2023 that highlight a variety of benthic types and list their classification.

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

Sample Images for Biotic and Substrate Classification – A set of slides presented at GeoTools 2023 that highlight a variety of benthic types and list their classification.

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.

The CMECS publication list is a living document that is updated on a regular basis. If you have examples to add to the map or the publications list, please email the CMECS Implementation Group at

Dynamic Standard Process (DSP)
CMECS was designed as a Dynamic Content Standard, allowing it to be updated periodically to reflect advances in scientific knowledge, technology, and the needs of coastal management communities. The CMECS Implementation Group developed the Dynamic Content Process (DSP) (see figure) to collect and evaluate change proposals and suggested revisions from the user community.

Who can propose changes to CMECS?
Anyone can propose changes to CMECS. Most change proposals will likely come from people who have used CMECS in their work and have identified ways that the structure or vocabularies would work better for them.

For example, practitioners may have used provisional units* to supplement the CMECS vocabulary, or they may have found that the defined ranges of a parameter aren't descriptive enough of their data. Change proposals can also address minor edits, such as grammatical or typographical corrections and clarifications of definitions and meanings.

* Provisional units are proposed new units that nest fully within the existing CMECS hierarchy and may be used where 1) there is no existing CMECS unit or 2) the provisional unit better describes the existing CMECS unit. Provisional units are most likely to occur in the Geoform component as new geoforms or in the Biotic component as new biotic communities.

Proposing CMECS Revisions
Requests for formal changes or addition of new units should be submitted through the Proposed Change Request Form. Please read the following guidance documents before submitting a change proposal:

Questions about the CMECS update and the DSP can be sent to