for lakes and ponds. Over time, sediments fill up ponds and lakes. As the depth decreases, the number of aquatic plants increases. Emergent aquatic like plants, cattails, sedges, and rushes begin to move out from the shoreline areas. These plants start to build a soil base where water-tolerant shrubs, grasses, and other plants start to move in. If left undisturbed, grasses and shrubs will eventually be replaced by larger trees and forest.
Aquatic Food Chain
Food chains are simplified models that describe the general flow of energy and food pathways that link different species in an ecosystem. At the base of the aquatic food chain are the primary producers—aquatic plants, algae, and phytoplankton. Primary producers are known as autotrophs, or organisms that can produce their own food.
Energy from the sun is the driving force of any ecosystem. Light energy, carbon dioxide, and water are converted to chemical energy (carbohydrates) by primary producers through a process called photosynthesis. This chemical reaction is described in Figure 4-9.