<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-387" name="Phytoplankton" parent="BC-384" scope="Biotic Class: This class includes areas of floating or suspended microscopic algae that are capable of photosynthesis. ..."/><bt><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><nt><term thcode="62" code="BC-474" name="Chlorophyte Phytoplankton" parent="BC-387" scope="Biotic Subclass: Areas dominated by Chlorophytes (green algae that are unicellular, flagellated, and sometimes colonial phytoplankton), occurring more predominantly in the tropics."/><term thcode="62" code="BC-411" name="Chrysophyte Phytoplankton" parent="BC-387" scope="Biotic Subclass: Waters dominated by Chrysophyte Phytoplankton, single-celled algae found mostly in freshwater (although several orders occur in brackish and salt water). ..."/><term thcode="62" code="BC-412" name="Coccolithophore Phytoplankton" parent="BC-387" scope="Biotic Subclass: Coccolithophores are small phytoplankters, predominantly marine, which produce plates of calcium carbonate as shells."/><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-414" name="Cyanophyte Phytoplankton" parent="BC-387" scope="Biotic Subclass: Areas dominated by cyanophytes, blue-green algae that are photosynthetic bacteria. Some of these are nitrogen fixing, some form resting cysts, and they can exist singly or in colonies."/><term thcode="62" code="BC-415" name="Diatom Phytoplankton" parent="BC-387" scope="Biotic Subclass: Waters dominated by Diatom Phytoplankton, single-cell algae that circulate passively or sink in the water column. ..."/><term thcode="62" code="BC-416" name="Dinoflagellate Phytoplankton" parent="BC-387" scope="Biotic Subclass: Areas dominated by flagellated phytoplankton that have some motility and can control their position in the water column to a degree, diurnally migrating from surface to bottom to maximize conditions for growth. ..."/></nt></descriptor>