Odum's field work on the energetics and productivity of coral reefs, lakes, fresh-water springs, and tropical rain forests show the utility of studying 
(Odum's field work on the energetics and productivity of coral reefs, lakes, fresh-water springs, and tropical rain forests; show; the utility of studying)
Odum's field work on the energetics and productivity of coral reefs, lakes, fresh-water springs, and tropical rain forests
show
the utility of studying