Zonation

Zonation

Zonation - Penetration of light through water varies with the depth in lakes and ponds. Based on this various zones can be recognized within the lake. The depth upto which effective penetra60n of light occurs is referred to as light compensation level.

The open area found above the light compensation level in a lake is called limnetic zone. Photosynthetic activity is maximum in this zone. Organisms include photosynthetic bacteria, flagellates and diatoms.

The part of thelimnetic zone where light penetrates upto the bottom is called littoral zone. This zone is characterized by rooted vegetation. The combined littoral and limnetic zone is called euphotic zone since both the regions are characterized by effective light penetration. Euphotic zone constitutes the most productive zone of a lake.

The deeper region below the light compensation level is characterized by a progressive decrease in photosynthetic activity and is called profundal zone. The bottom region of lake which is composed of mud and ooze is known as benthic zone. Both profundal and benthic zone have a heavy population of heterotrophic bacteria.

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