Question

Choose the correct combination of labelling of the zones in water in a lake :
a) A - Limnetic zone, B - Profundal zone, C - Littoral zone, D - Benthic zone
b) A - Littoral zone, B - Benthic zone, C - Profundal zone, D - Limnetic zone
c) A - Littoral zone, B - Limnetic zone, C - Profundal zone, D - Benthic zone
d) A - Limnetic zone, B - Littoral zone, C - Benthic zone, D - Profundal zone
e) A - Littoral zone, B - Profundal zone, C - Benthic zone, D - Limnetic zone

Answer 1

Hint: All lakes have various zones dividing the water areas from top to bottom and side to side.
These zones are - the Littoral Zone, the Limnetic Zone, the Profundal Zone, and the Benthic Zone.

Complete answer:
Freshwater (little or no salt) biotic community includes biomes from running water as well as standing water.
Biomes of standing freshwater include ponds and lakes.
Ponds are usually smaller as compared to lakes. In Ponds, sunlight can somehow reach a much better level relatively.
In lakes, some water is very deep for the sunlight to reach.
As a result, on the basis of sunlight’s availability for producers, lakes are divided into the following zones:-
The Littoral Zone is basically the lake’s shore area. It consists of the region from the dry land to the open water.
In this zone, the Producers include both - phytoplanktons and plants - that float in the water.
They provide food and oxygen to other aquatic beings.
Thus, it has abundant growth of algae & aquatic plants.
The Limnetic Zone is usually the open water area of the lake or pond or the top layer of lake water, away from the shore. Also, it has dense fish populations because oxygen levels here are higher due to the air’s contact.
The profundal zone or hypolimnion (cold water region) is the deep water near the bottom of the lake, where the sunlight does not reach. It has lower populations of fish, because of the lack of oxygen at most of the times.
The last one is the Benthic Zone. This is the bottom of the lake and contains soil and organic sediments. The plants here provide food and oxygen, along with protection from other predatory organisms.
It is the digestive system of the lake, because here the bacteria decompose the organic matter from dead matters and organic wastes. Aerobic decomposition is quite better because it is a fast process and the byproducts are easier to handle.

So, according to the information mentioned above :

Option c) A - Littoral zone, B - Limnetic zone, C - Profundal zone, D - Benthic zone is the Correct option. The sequences in all other options are incorrect.

Note: The littoral zone is higher in productivity and biodiversity as compared to the limnetic zone.
In the profundal zone, photosynthesis cannot take place, since there are no producers in this zone.