Q9 of 30 Page 1

‘Fish mortality increases with influx of nutrients in a fresh-water body.’ Write two reasons. How will the influx of nutrients affect the BOD level of this water body?

Excess nutrients, such as nitrogen, phosphorus, stimulate algal blooms. The algal bloom is followed by an algal die off. Setting of the dead algae stimulates an increase in biological oxygen demand (BOD) as population of microorganisms increases and consume more dead algae. Hence, mortality of fish increases.


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