PORTLAND, Maine (AP) — A boom that saw Maine fishermen harvest millions of pounds of sea urchins for the lucrative Japanese market depleted the spiny sea creatures, turning the ecosystem upside-down and creating an ideal habitat for an urchin predator that has flourished, according to a new scientific study.

The urchin bonanza of the 1990s triggered an ecological chain reaction that “flipped” the ecosystem from one with a stable amount of kelp and Jonah crabs to one with an overabundance of kelp and crabs — and a lack of urchins, the study said.