Question

A lake which is rich in organic waste may result in :

• A. increased population of fish due to lots of nutrients
• B. mortality of fish due to lack of oxygen
• C. increased population of aquatic organisms due to minerals
• D. drying of the lake due to algal bloom

Answer 1

The correct option is B mortality of fish due to lack of oxygen

When much of the organic matter is present in lake, lots of microbial activity takes place in its decomposition process. So, demand for oxygen increases. This increased $O_2$ demand depletes the oxygen in water at faster rates. This adversely affects the living conditions for other organisms like fishes, etc., ultimately causing their death.