Lakes and Ponds

             A lake is a large body of fresh water. Lakes can range in size from small ponds to huge bodies of water such as the Great Lakes in the United States. Many ponds are seasonal. They last for a couple of months while lakes may exist for many years. A pond is a body of water that is shallow enough to support rooted plants. Many times, plants grow all the way across a shallow pond. The water temperature is even from top to bottom and it changes with the air temperature. There is hardly wave action and the bottom is covered with mud. Plants can often grow along the pond edge. In really cold places, the entire pond can freeze solid. Lakes are bigger than ponds, and it is too deep to support rooted plants except near the shore. Some lakes are big enough for waves to be produced.

             Water temperatures in lakes during summer months are not the same from top to bottom. The top layer stays warm around 65-75 degrees. The middle layer drops to 45-65 degrees. The bottom layer is the coldest, staying around 39-45 degrees. Since lights does not make it to the bottom of the lake, photosynthesis is limited to the top layer of the lake. During spring and fall, the lake temperature is alright. Fish and other animals are found throughout the lake. In cold climates, most lakes are large enough, so they don't freeze solid, unlike ponds do. During the winter months, some animals hibernate in the bottom mud. Some fish continue to feed, but they hardly do it actively all the time. A layer of ice can form on the top of lakes during winter. Then, the ice will blockout sunlight and will prevent photosynthesis. Without photosynthesis, oxygen levels drop and some plants and animals may die.

Resources: Science class