I don't have numbers to support it but I seem to remember the Lionfish is the most voracious predator of its size to weight of food consumed per day. They can wipe out an areas species population by destroying the juvenille population in weeks. They are a particularly efficient predator.

Agreed it is a short term problem as Nature will balance it. Man damaging the reef/planet is also a short term issue as it will rebound - it might be a couple of million years time but nature has time on its side, not sure man does.