Co-extinction and introduction of alien species too are responsible for the loss of biodiversity. Explain, how.

OR

Explain how biomagnifications of DDT occurs in an aquatic food chain.

The biodiversity is the presence of the different organism in the ecosystem. It effects by different causes but one of the major causes is by humans; human activity is a major threat to biodiversity. This is because of the rapid increase in human population growth. This makes the population grow faster and faster as it gets larger. One of the causes of human-mediated biodiversity loss is the introduction of alien species. Humans may intentionally or unintentionally introduce an alien species into an ecosystem. This can negatively affect an ecosystem because the introduced species may out-compete fundamental organisms and displace them. Co-extinction refers to the loss of one species as a result of the extinction of a species, it depends on and models suggest that co-extinction should be the most common form of species loss. The activities like capturing and harvesting (hunting, fishing, farming) in a renewable natural resource in a particular area is very hard, the resource itself may become empty, as for example, is the case of sardines, herrings, cod, tuna and many other species that man captures without leaving enough time for the organisms to reproduce.

OR

Biomagnifications is an increase of the concentration of the toxic matter at progressive trophic levels due to the accumulation of a toxic substance by an organism. It cannot be metabolised or eliminated, therefore passed on to the next higher trophic level with a food chain, for example, DDT (Dichlorodiphenyltrichloroethane). In this situation, the penetration of the small concentration of DDT get accumulated in the water organism like a tadpole, the small fishes consume those tadpoles as the food source so the DDT accumulated in the fish. Moving forward along the food chain the big fishes feed on those small fishes, again the birds like kingfishers eat the big fishes and concentration of DDT increase with the higher trophic food chain consumers. High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing a drop in bird populations.