Question

How does an algal bloom cause eutrophication of a water body? name a weed that grows in such a eutrophic lake?

Answer 1

Hint: Eutrophication is the enhancement of the biological productivity of water bodies due to the accumulation of nutrient elements under the action of human-induced or natural factors.

Complete answer:
Eutrophication is the natural aging process of the lake by nutrient enrichment of its water. During eutrophication, algal blooms release toxic chemicals that kill birds, fishes, and other aquatic animals causing the water to sink. The decomposition of algal blooms leads to oxygen depletion in the water. Thus with a high (CO), level, and poor oxygen supply, aquatic organisms begin to die and therefore the clean water turns into a stinking drain. So, When (O), the level falls to zero (anaerobic zone), some bacteria drive oxygen through the reduction of nitrates. When complete exhaustion of nitrate is completed, oxygen may as a final resort be obtained by reduction of sulfate yielding hydrogen sulfide causing the foul smell and putrefied taste of water. The characteristic feature of eutrophication is the excessive growth of aquatic and coastal plants (reed, typha, pond grass, waterweed).

The weed that grows in such a eutrophic lake is Eichhornia crassipes/water hyacinth.
From the moment of "birth," a water body passes several stages in its development firstly from ultra oligotrophic to oligotrophic and then to mesotrophic, and, finally, to eutrophic and hypereutrophic, i.e. aging and death to form a swamp. However, human activities impart specific features in this natural process. The rate and intensity of the productivity enhancement of ecosystems sharply increase.

Note: Due to over-fertilization algae and diatoms have a high degree of dominance. Algae and rooted weeds interfere with the clog the filters, hydroelectric power, retard the water flow, and affect water quality. Macrophytes, particularly Hydrilla, Myriophyllum, Potamogeton, and Ceratophyllum assume high population densities making nearshore and shallow regions unsuited for any further purpose.