Question

A freshwater organism cannot survive in a water body that has greater _____that its original habitat.
A) Oxygen content
B) Depth
C) Salt concentration
D) Water clarity

Answer 1

Hint: It is usually expressed in terms of parts per million(ppm) and the level of saturation depends on the temperature of the water. The quality of water is very much important for aquatic organisms.

Complete Answer:
- Freshwater is naturally occurring water except seawater and brackish water. It is characterized by having low concentrations of dissolved salts and other dissolved solids. The quality of water includes pH, chemical composition, salt concentration, etc.
- The salt concentration is measured as salinity in terms of parts per thousand or parts per million(ppm). Salt concentration is less than 5 parts per thousand in the sea and more than 100 parts per thousand in some hyper saline lagoons.
- Many freshwater organisms cannot live in a water body that has greater salt concentration. Or because of the osmotic problems they would face. Some organisms can use salt water to survive but the majority of the organisms including mammals require fresh water to live.
- Hypotonic environment created by fresh water for aquatic organisms.
- Most of the aquatic organisms have restricted ability to maintain their osmotic balance and therefore, can live only within a narrow range of salinity.

Thus, the correct answer is option C i.e., Salt concentration.

Note: Water is a critical issue for the survival of the aquatic organisms. Some desert or terrestrial organisms live without drinking water and sometimes, they can also use salt water for their survival. But aquatic organisms can only survive in low salt concentration.