Habitat - Lakes are inland depressions containing standing water, varying in size to thousands of square miles, and in depth from a few feet to over 5,000 feet (1,524 meters). Only a relatively small proportion of the water is in direct contact with the air. Since decomposition of material takes place on the bottom, the oxygen content of lake water is relatively low compared to running water. The energy source of a lake is sunlight, and therefore food production is greatest in Lakes that are relatively shallow and rich in organic matter.
Ponds are small, relatively shallow bodies of water that have uniform temperatures and rooted plants can grow over most of the bottom. Like Lakes they are doomed to disappear, and become marshes. Each pond is a self-contained miniature world harboring its own distinctive population of plant and animal life. No two Ponds are ever alike, and no one pond remains the same for very long. There are millions of Ponds in North America, many of which are human-made south of the Arctic. Prairie potholes and sloughs are also Ponds. In the United States, there are estimated to be two million acres (4.9 million hectares) of Ponds, a major aquatic habitat. Early Ponds were glacial Ponds, potholes, beaver Ponds and kettles. Today, most Ponds are made by human activity such as ditches, canals, small reservoirs, millponds, quarry ponds, fishponds, and watering holes for domestic stock.
Ponds are greatly affected by the seasons, with their varying temperatures, light, and rainfall. They may dry up in the summer, or freeze in the winter. Most Ponds are smaller than an acre (2.5 hectares), and the energy source is usually high. Many Ponds are barren in winter.
Lakes and Ponds may be surrounded by trees, or if situated in open country, by shrubs and tall plants like reeds. Some have a blanket on pond lilies that choke the surface. Birds such as the Common Yellowthroat, Northern Waterthrush, Red-winged and Yellow-headed Blackbird may breed and sing from these damp areas. Shorebirds, like the American Avocet, Killdeer, and Spotted Sandpiper call from the shores. And Mallards, Pied-billed Grebes, and Common Loons can be heard on the water.
