<descriptor thcode="62"><thesaurus thcode="62" name="Coastal and Marine Ecological Classification Standard" scope="Categories of ecosystems for coastal, estuarine, and marine environments." creator="FGDC" rights="public domain" date="2017-05-10" codetype="alpha" prefix="cmecs" uri="https://www2.usgs.gov/science/CMECS" tblname="cmecs" root_code="root" contact="pschweitzer"><category><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/></category><altlabel><altlabel>CMECS</altlabel><altlabel>CMECS</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel></altlabel></thesaurus><term thcode="62" code="AS-016" name="Marine Offshore Subtidal" parent="AS-005" scope="Tidal Zone: The substrate is subtidal and continuously submerged in this zone and includes those areas below MLLW."/><bt><term thcode="62" code="AS-005" name="Marine Offshore" parent="AS-001" scope="Subsystem: The Marine Offshore Subsystem extends from the 30 meter depth contour to the continental shelf break, as defined by the maximum slope discontinuity with a rapid change in gradient of 3&#xC2;&#xB0; or greater at the outer edge of the continental shelf. ..."/><term thcode="62" code="AS-001" name="Marine" parent="AS-C000" scope="System: The Marine System is defined by salinity, which is typically about 35, although salinity can measure as low as 0.5 during the period of average annual low flow near fresh outflows. ..."/><term thcode="62" code="AS-C000" name="Aquatic Setting" parent="root"/><term thcode="62" code="root" name="CMECS" scope="Coastal and Marine Ecological Classification Standard: Category terms encompassing waters from the head of tide or inland incursion of ocean salinity to the splash zone of the coasts to the deepest portions of the oceans and the deep waters of the Great Lakes."/></bt></descriptor>