364 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. There are some variances in the nomenclature used by each group but the defi nitions and qualifi cation standards for wetlands are very similar. Some of the criteria used to classify wetland types include plant life, soil type, water depth, depth of hydric soil, bed type, and the annual amount of time the wet- land is fl ooded and/or dry. The two main categories are marine (tidal) wetlands and freshwater (nontidal) wetlands. Additional categories include estuarine wetlands, riverine wetlands, lacustrine wetlands, and palustrine wetlands. Marine Wetlands Marine wetlands are found on coastlines, Figure 15-7. Marine wetlands are also affected by the tides and exposed to the waves and currents of the open ocean. Wetlands affected by the tide are referred to as tidal wetlands. In the United States, marine tidal wetlands are found along the Gulf, Atlantic, Pacifi c, and Alaskan coasts. Permanent shallow marine waters, such as sea bays and straits, are typically less than 20′ (6 m) deep at low tide. Wetlands referred to as marine subtidal, aquatic beds include kelp beds, seagrass beds, and tropical marine meadows. What are the economic impacts of marine litter? Thinking Critically Source: EPA Figure 15-7. Coastal watersheds can extend miles inland from the coast. The marine wetlands in the US coastal watersheds are experiencing more lost acreage than other wetlands across the country. Idaho Utah Nevada Arizona Montana North Dakota Minnesota Wisconsin Michigan Indiana Pennsylvania York Maine New Hampshire Massachusetts Rhode Island Connecticut Vermont New Jersey Delaware Maryland Virginia West Virginia Tennessee North Carolina South Carolina Mississippi Alabama Georgia Florida Arkansas Louisiana South Dakota Nebraska Oklahoma Texas Wyoming Colorado New Mexico Oregon Washington Kansas Iowa Illinois Ohio Kentucky Missouri California Canada Lake Superior L ake Mi chig an Lake Huron Gulf of Mexico Atlantic Ocean Pacific Ocean Lake Erie Lake OntarioNew Extent of Coastal Watersheds in the Conterminous U.S. Map Key State Boundaries Lakes North Atlantic Mid-Atlantic South Atlantic Gulf of Mexico Pacific Northwest California States