Surface films contain organic matter, rich in lipids which serves to trap contaminants from the atmosphere. At specific times of the day, surface films may also entrap significant numbers of zooplankton, which presumably were attracted to near-surface food supplies and fishes in pursuit of their zooplankton prey. Thus the surfaces of the Great Lakes, as well as of small ponds and the oceans, are relatively rich in both living and decomposing organic matter. Such films are likely microhabitats where lipid-soluble contaminants move with relative ease from one compartment to another in the food web. The author hopes that continued study of dynamic aquatic systems, as outlined in this volume and begining with the atmosopheric input of contaminants like PCBs and terminating with lake trout bearing unacceptable levels, will lead to solutions to the preservice of our Great Lakes and their significant resources for future generations.