<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="BC-479" name="Cryptophyte Maximum Layer" parent="BC-413" scope="Biotic Group: Relatively thin layer dominated by cryptophytes at depth in the water column. Motility allows the group to avoid predation and to optimize their heterotrophic grazing."/><bt><term thcode="62" code="BC-413" name="Cryptophyte Phytoplankton" parent="BC-387" scope="Biotic Subclass: Waters dominated by cryptophytes, a small?but diverse?group of unicellular algae that occur in fresh and salt water. Some species are mixotrophic and are able to thrive in low-nutrient environments."/><term thcode="62" code="BC-387" name="Phytoplankton" parent="BC-384" scope="Biotic Class: This class includes areas of floating or suspended microscopic algae that are capable of photosynthesis. ..."/><term thcode="62" code="BC-384" name="Planktonic Biota" parent="BC-C002" scope="Biotic Setting: Planktonic Biota includes biota that drift, float, or remain suspended in the water column in aggregations that are big enough to be (a) detected by the human eye (or with mild magnification) or (b) sampled with a fine-plankton net. ..."/><term thcode="62" code="BC-C002" name="Biotic" 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>