How can sewage discharge affect the aquatic creature ?

How does the unrestricted growth of weeds in water bodies affect the aquatic animals ?

How do algal blooms affect the aquatic life ?

What do you mean by anomalous behaviour of water? How it can be helpful for the survival of aquatic creatures in polar region?

How can waterlogging affect the growth of crop ?

How can waterlogging affect the growth of crop ?

Explain the change that can be observed in the characterstics of river water when sewage is discharged into it and a few weeks after the discharge with respect to (i) level of dissolved oxygen (ii) Population of fresh water organisms.