I read that page through, and didn't find it particularly compelling. Do you have anything that isn't 5 years old, and that doesn't try to talk around the issue by redefining terms?
What I mean is that when I think of when I would say "the ocean is dying," I'm referring to things like declining fish populations, coral reefs dying off, and the oceans themselves getting warmer and more acidic.
These things are undoubtedly happening. We have measured them, and we are causing it. Your link seems to say something like "the ocean isn't dying, because we still can do something about it." I'm not particularly concerned with this "ocean health index" they mention. I am not concerned with what we "can" do; I'm only concerned with what we are and will be doing. And, at this rate, what we are doing is not enough.