Otters love to eat sea urchins, and sea urchins love to eat kelp. When otters were killed in the fur trade, they migrated south, and sea urchin populations boomed. This resulted in a drastic decline in kelp forests and formed what we call "dead zones". The name comes from the fact that oxygen levels are depleted so much to the point where marine life can no longer survive, and you would likely find a graveyard on the ocean floor. Otters love to eat sea urchins, and sea urchins love to eat kelp. When otters were killed in the fur trade, they migrated south, and sea urchin populations boomed. This resulted in a drastic decline in kelp forests and formed what we call "dead zones". The name comes from the fact that oxygen levels are depleted so much to the point where marine life can no longer survive, and you would likely find a graveyard on the ocean floor.