Pollution of pesticides and insecticides caused thin eggshells in predatory birds such as eagles, and hawks. The pollutants accumulated in the top trophic levels through food chains. Name that phenomenon. 

Biomagnification refers to an increase in the concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolized or excreted, and is thus passed on to the next higher trophic level