Freshwater ecosystems include lakes, ponds, rivers, streams, springs, and wetlands. There are two main types - lentic ecosystems, which are standing bodies of water, and lotic ecosystems, which are running water. Lentic ecosystems can be further divided into zones based on depth and vegetation. Lotic ecosystems have rapid zones with strong currents and pool zones with slower currents. Wetlands are areas that are periodically saturated or flooded with shallow water and support unique plant and animal communities. Forested wetlands include swamps and floodplain forests while tidal freshwater marshes occur along estuaries. Freshwater ecosystems provide important resources but occupy a small area globally.