Rooted aquatic plants, when present, are another important part of a pond s food web. Contrary to popular belief, however, it is not necessary to have rooted plants in a pond for it to be considered healthy. In the absence of rooted plants, phytoplankton and the direct diffusion of oxygen from the atmosphere will produce sufficient dissolved oxygen for a pond to maintain excellent living conditions for aquatic animals. Their leaves and roots provide shade, cover, food, and a suitable substrate or base on which aquatic animals may lay their eggs. In addition, many wildlife species feed on the seeds produced by some of these plants.
Many factors affect the ecology of a pond.
Geographical location is most important because it will determine the climate. Climate, in turn, affects important habitat characteristics such as water temperature and the amounts of rainfall and sunlight that a pond may receive. Also, a pond may receive excessive nutrients such as phosphorous and nitrogen from fertilizer runoff. This fertilizer pollution feeds the phytoplankton and can cause their populations to increase substantially. These algal blooms, as they re called, cause dissolved oxygen levels to fluctuate dramatically and can even cause a complete, or nearly complete, depletion of oxygen at night that will kill almost all gill-breathing aquatic life.