English: Biomagnification of toxins in the food chain of a terrestrial environment. The dots represent the organic molecules present in each trophic level. The crosses represent the mercury present in each trophic level. While dots remain relatively constant in each individual, the concentration of crosses become greater in each preceding trophic level.

Biomagnification: An increase of toxin concentration as the food chain moves up to higher levels. Organisms at the top have a higher tissue concentration of toxins and pollutants than lower levels. The concentration system is due to persistence of the toxins, food chain energetics, and low rate of internal degradation or excretion of the substance.Trophic level I represents the primary producers. Trophic level II represents the primary consumers. Trophic level III represents the secondary consumers. Trophic level IV represents the tertiary consumers.

Per: http://www.thefreedictionary.com/biomagnification http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/D/DDTandTrophicLevels.html

Biomagnification