Examples of producers in lakes and ponds include algae, phytoplankton, starwort, spiked water milfoi, great willowherb, water lilies, native grasses and wildflowers. Aquatic plants come in three varieties: those that grow completely underwater, those that float on water and those that root underwater but reach above the water's surface.
The littoral zone of a lake or pond is shallow enough to allow light to shine all the way to the bottom. In this zone, plants such as grasses, trees and flowers root at the bottom while oxygen-exchanging leaves are above the surface.
The limnetic zone, towards the middle of a lake, does not let sunlight reach the bottom. However, aquatic plants that float on water thrive in this region. Algae, water lilies, duckweed, frogbit, starwort, crowfoot and spiked water milfoi produce energy through photosynthesis.
Some forms of algae choke the ecosystem of a lake or pond by using all of the oxygen in the water and blocking sunlight at the surface. Huge blooms of blue-green algae thrive on phosphorus and nitrogen carried to lakes by water runoff from agricultural fertilizer applications.
Aquatic plants, both near shore and in the middle of lakes and ponds, provide food for primary consumers such as insects. Bugs, in turn, provide food for predators including spiders, frogs, lizards, fish and many other life forms in lakes and ponds. Fish potentially provide food for humans.