This chart shows the PCB concentrations found at the various…

This chart shows the PCB concentrations found at the various trophic levels in the Saginaw Bay ecosystem of Lake Huron. Notice that the fish in the higher trophic levels accumulate more PCBs than those in lower trophic levels. (credit: Patricia Van Hoof, NOAA) Other examples are:  DDT (pesticide) accumulating in birds of prey (raptors), Mercury levels being too high in mackerel, etc. What does the figure below demonstrate?