Question

How is calcium metabolism associated with biological magnification in birds?

Answer 1

Biomagnification refers to the increase in concentration of the toxic waste at successive tropic levels. Biomagnifications of DDT in an aquatic food chain causes the increase in concentration of DDT at successive tropic levels.

Fish eating birds (DDT 5ppm)

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Large Fish (DDT 2ppm)

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Small Fish (DDT 0.5ppm) and Zooplankton(DDT 0.04ppm)

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Water(DDT 0.003ppb)

Now we know about biomagnification, Lets see how it is associated with calcium metabolism.Mainly DDT and Hg is involved in bio magnification. Thus the amount of DDT in bird body will be high due to bio magnifcation.Calcium is a major part of birds body which helps in strengthening of bones and egshells. Calcium metabolism in birds is known to be mainly regulated by oestradiol and vitamin D.
The DDT causes the increased production of oestradiol which causes more calcium to be stored inthe body of birds. But it is never used for metabolism. And hence as a result of this following problems happen:

1, Premature cracking of egg shells
2, Thining of egg shells. (thin eggshell phenomenon)

As a result of this the newborns die and the entire bird population is affeted

Conclusion : Bio magnification leads to increased content of DDT in birds body which affects calcium metabolism in birds body, which causes thin eggshell phenomenon. Pollution is the main cause of this.