Zonation of pond

A pond can be conveniently divided into different zones. The various zones and their important biota are as under:

Littoral Zone: Littoral zone is the shallow water zone near the shore, with upper and oxygen rich circulating water layer. In this zone enough light penetrates to the bottom to support rooted aquatic plants.

At the shore there is emergent vegetation, which remains firmly rooted in the shore substratum but their tops are exposed. E.g., Monochoria, Cyperus, Typha.

Slightly deeper in the littoral zone are the rooted plants with floating leaves.

E.g., Nymphaea, Trapa, Marselia.

Besides the above mentioned macro-phytic vegetation, certain phytoplankton are also present.

E.g., Diatoms, Green algae, Euglena etc.

The zooplankton of littoral zone are mainly represented by Rotifers, Copepods, & Ostracods etc.,

Littoral zone also contains a great concentration of animals.

E.g., Dragonfly nymphs, worms, snails, flatworms, hydra, nektons (mosquito larvae, frogs, small weed fishes, snakes, turtles), neustons (protozoans, water spiders).

Limnetic zone: Limnetic zone is the open water zone away from the shore up to the depth of effective light penetration where the rate of photosynthesis is equal to the rate of respiration. The water level, temperature and oxygen levels vary from time to time.

This zone is full of autotrophs i.e., free floating algal forms. Most of the fishes to be cultured will occupy this zone.   

Profundal Zone: Profundal zone is the deep water area beneath limnetic zone, beyond the depth of effective light penetration. Autotrophs are wanting in this region. All the organisms living here are the heterotrophs either detritivores, carnivores, decomposers or transformers. Bacteria, fungi, clams, blood worms, annelids, etc. are common forms. Most of the large-sized fishes often visit to this zone.

References: Gupta, S. K., and Gupta, P. C., (2006), General and applied ichthyology.