The sea urchins then overexploited their main food source, kelp, creating urchin barrens where no life exists. No longer having food to eat, the sea urchins populations became locally extinct as well.
In this scenario, the sea urchins' exploitation of their primary food source, kelp, had severe consequences. The resulting barren areas devoid of life ultimately led to the local extinction of the sea urchin population due to starvation.