bill laurance: but i think we have to be very vigilan it's absolutely essential to understand for the fate of tropical biodiversity what species are gonna be able to persist and which ones are not going to be able to survive in these fragments oforest. narrator: coral reefs have been called the rainforests of the sea. and like the rainforests, they are a rich and precious natural resource. but they, too, are being impacted by human action. one small example of this impact took place in april 1986, when a major oil spill on the coast of panama polluted an area of coral reefs, mangrove forests, and grass beds, including a biological reserve being studied by the smithsonian tropical research institute. ecologist jeremy jackson is one of a group of scientists working there hired to study the ecological effects of the spill. dr. jackson: we worked all the way down the coast for something like 50, 60 miles to get to places that were less and less affected by the spill. and so we had what were in effect control reefs that were along the coast, and we were monitoring the condition on the cora