The idea that intact trophic structures and diverse ecosystems are more resilient than their depauperate over-extracted kin has been tossed around in scientific circles for many years. The diversity = resilience hypothesis is getting new scrutiny in the oceans today because of the threats of acidification and warming temperatures. Can the seas survive better if they get to keep all their parts (even if we don't understand exactly how they work)?
The August issue of Current Biology has new evidence saying yes. Dr. Hugh Sweatman and many brave associates spent ten years being towed around the Great Barrier reef counting crown-of-thorns starfish. COTs are nasty, poisonous little buggers that swarm in waves, eating corals. Researchers found that areas open to fishing were 3.75 times more likely to have COTs outbreaks than no-take marine reserves in the same area. Adult fish aren't direct predators on the starfish -- since almost nothing can eat a 10" diameter helping of neurotoxins -- but having them around may protect invertebrates that prey on juvenile COTs. Time for more manta tows to figure out the causal mechanism and in the meantime, keep those marine reserves going.
You can get the full paper through the Australian Institute of Marine Science website.
Crown of Thorns photo © Alexey Bogdanov