A physiologically interactive system within which growth, adaptation, species composition, nutrient cycling, biological productivity, and energy flows among inland aquatic microbial, plant, and animal communities are integrated with the environment. These inland waters include lakes, reservoirs, rivers, streams, and wetlands. The discipline termed limnology evaluates how these relationships regulate, and are regulated by, natural and anthropogenic variations in the physical, chemical, and biotic environments. The standing-water (lentic) lake or reservoir ecosystem is intimately coupled with the land in its surrounding drainage area and with its running (lotic) waters that change chemical components from the land as they are transported to the lake. Often the land-water interface supports productive wetlands, that is, areas of shallow water often found at the edge of lakes (littoral zone) or along rivers (floodplain).