That is interesting. I had not heard Octopuses (octopi) were the "weeds" of the oceans. But it is interesting to find larger animals that can be a litmus test of the ocean environment.
Oceans are not sucking up CO2 at the same rate as they used to. Acidification is moving up quickly. Reefs are under massive threat.
Weeds are mother natures way of getting something growing in bad soil and going in destroyed areas.
Here's the original study in Scientific America:
'via Blog this'