Please will you help me out with this so i can go to bed? Ive been up on this all day?

Question

Explain how the sea otter functions as a keystone predator?

List the steps of the chain reaction, starting with over-fishing in the open waters, that has led to the destruction of the coastal ecosystems off the coast of western Alaska.

Im not cheating or anything soo don't assume that of me, i am a senior in high school if i answer these last two questions on my research assignment i can pass.

Answer 1

The sea otter is a keystone organism for the Pacific kelp "forests."  Kelp forests have a rich biodiversity;  the kelp provides food and hiding places for lots of fishes and other marine life.

Part of the sea otter's diet was the sea urchin.  The sea otters were hunted (by people) to near-extinction.  It turns out that with the sea otter gone, the sea urchins experienced a population explosion.  The great numbers of sea urchins chewed through the holdfasts of the kelp.  The kelp drifted away and died, and thus the whole system supported by the kelp forest also collapsed.  Unfortunate.