composed primarily of fresh water estuarine open water pycnocline estuarine tidal riverine open water pycnocline envoCmecs envoMarine https://cmecscatalog.org/cmecs/classification/unit/609.html CMECS:609 What causes this freshwater layer to be "tidal" is not clearly specified in the current CMECS definition. Further, the original definition and label do not clearly state whether this is a pycnocline in its own right, or just the tidal freshwater part of the pycnocline. In this ENVO class, we follow the semantics suggested by the label and treat this as a type of estuarine open water pycnocline. This class aligns to the Coastal and Marine Ecological Classification Standard (CMECS). In ENVO, we may adapt the definition for consistency, but the semantics (meaning) of the term should be unaffected. Please consult the CMECS catalogue (https://cmecscatalog.org/) for authoritative and semantically unconstrained definitions. An estuarine open water pycnocline which is composed primarily of fresh tidal water.