If otters were to die, the population of their prey, such as sea urchins, would increase in number. This increase in the number of sea urchins would cause overgrazing of kelp forests, as sea urchins are known to feed on kelp. Kelp forests are important marine ecosystems that provide a habitat for a wide variety of marine organisms, including fish, crustaceans, and mollusks. Without otters to keep the population of sea urchins in check, the kelp forests could be seriously damaged or destroyed.
Therefore, the absence of otters could lead to a chain reaction that could ultimately impact the entire ecosystem of kelp forests.