Sea otter decline led to sea urchin overpopulation, impacting the ecosystem.
Sea otters were the main predator of sea urchins along the Pacific Coast, but they were overhunted in the 18th and 19th centuries, leading to a decline in their population.
The absence of sea otters allowed the sea urchin population to grow unchecked, resulting in the overgrazing of kelp forests, creating 'urchin barrens.'
This uncontrolled sea urchin population growth was further exacerbated by a decrease in sea otter numbers due to predation by killer whales, causing a chain reaction affecting the marine ecosystem.
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