Dr. Robert Steneck, University of Maine, discusses his fascinating work on species interactions - how exploitation changed the face of the Gulf of Maine, from cod and kelp, to sea urchins and coralline algae, to havens for predatory crabs. "Flip and lock"  relates to alternative stable states in kelp forests and the ecological feedback mechanisms that lock them into those states.  The slow driver is the extirpation of fish that held mobile benthic invertebrates in check. Once the predators were gone, sea urchin, lobster, and crab populations exploded.  The dynamics changed again when sea urchins were targeted as a fisheries species.