Fresh water lakes have variety of size, depth, and nutrient content. The have distinct life zones and temperature stratification. The distribution of life in lakes depends on light, nutrients and place for attachment. Thus different life zones are formed in the lake and ponds on the basis on access to light and nutrients: The lake ecosystem can be divided into three main zones.
- Littoral zone (Near–shore)
The area near shore is called littoral zone. In this zone, the water is shallow. us the plants find abundant light and adequate nutrients from the bottom sediments.Plants in littoral zones: The littoral zone communities have most diverse plants. Some of these plants are water lilies, submerged vascular plant and algae. These plants flourish at the deepest of the littoral zone.( ) Planktons: The microscopic floating organisms are called planktons.Planktons are present among the anchored plants. These can be divided into two groups:
(i) Phytoplankton: The photosynthetic planktons are called phytoplanktons. These are photosynthetic protista, bacteria and algae.
(ii) Zooplankton: The non-photosynthetic planktons are called zooplanktons. These are protozoa and tiny crustaceans.
Animals in littoral zone: The greatest diversity of animals is present in this zone. Littoral invertebrate animals include small crustaceans, insect larvae, snail flatworms, Hydra. Vertebrates include frogs, aquatic snakes and turtles.
2 Limnetic zone
T e open water area where enough light can penetrate is called limnetic – z•ne. In this zone, enough light penetrates to support photosynthesis.
(a Producers: Here, producers are phytoplankton and cyanobacteria (blue green algae).
(b Consumers: The producers are eaten by protozoa and small crustaceans. Finally the fishes consume these protozoa and crustaceans.
- Profundal zone
T e bottom area of a lake, where light cannot penetrate is called profundal z• e. Here, light is insufficient to support photosynthesis. This area is mainly n• rished by .detritus. This detritus falls from the littoral and limnetic zone by interning sediment. Decomposers and detritus feeders such as snails and certain in ect larvae, bacteria, fungi and fishes live in this zone.