Question

Explain the following : (i) Eutrophication ; (ii) Biomagnification.

Answer 1

(i) Eutrophication is nutrient enrichment (i.e., addition of nitrates and phosphates) of water body that results in the growth of aquatic plants, especially algae causing colouration of water known as algal bloom. It leads to depletion of dissolved oxygen in water resulting in killing of aquatic organisms (e.g., fish).

(ii) The phenomenon of increase in the concentration of harmful non-biodegradable substances in the body o' living organisms at each trophic level of the food chain Is called biomagnification. Two heavy metals which are biomagnified are mercury and cadmium. Due to biomagnification fish-eating predatory birds such as kingfishers and loon become poisoned.