Answer:
keystone species
Step-by-step explanation:
The sea otter is an example of a keystone species in the scenario.
A keystone species is an organism that has a significant influence on the functioning of the entire ecosystem. Without this species, the ecosystem would either cease to exist in total or entirely different in structure. In other words, a keystone species is a fastener that holds the ecosystem together.
In this case, the sea otter indirectly regulates kelp for all organisms in the ecosystem by directly regulating the presence of sea urchins. Without kelps, several ecosystem functions such as climate change mitigation and erosion reduction would cease. Thus, the sea otter is playing a significant role as a keystone species.