has part adjacent to aquatic estuarine layer liquid air-water interface layer estuarine open water surface layer estuarine open water upper water column "Mid-depth", present in many CMECS classes, is ambiguous and needs refinement. https://cmecscatalog.org/cmecs/classification/unit/600.html CMECS:600 envoMarine envoCmecs A layer of estuarine water which extends from the surface of the water column to the pycnocline or mid-depth and from a fiat boundary where the estuary bed below the water column reaches a depth of 4 meters until the end of the estuary most distal from the coast. 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. estuarine open water pycnocline surface of an astronomical body