The HELCOM Undewater biotope and habitat classification system (HELCOM HUB) provides a framework for defining biotopes in the whole Baltic Sea. Defining biotopes by the same split-rules, enables comparison of the biotopes in different regions of the Baltic Sea.
Habitats are defined as the abiotic environment in HELCOM HUB. Biotopes are defined as the abitotic environment coupled with the characteristic organism community. Biotope size and structure is not strictly defined, the HELCOM HUB is hierarchial and structured into six levels. Between every level clearly defined split-rules delineate the biotopes.
Biotopes should always be classified down to the lowest possible level allowed by the data. Generally benthic biotopes are classified down to Level 5 or Level 6. Pelagic biotopes are classified to Level 4.
The HELCOM HUB was developed as a part of the HELCOM Red List project. In the project the decline in quantity and quality of biotopes on the scale of the whole Baltic Sea was compared. HELCOM HUB was created to be EUNIS compatible.
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