I would like to point out however that you are not really addressing edge effects at all in your lake example.
I wasn't trying to. Let's review.
It doesn't matter if the usage of my land changes the wildlife on your land.
More interesting are your opening three words: "It doesn't matter...". I would appreciate an explanation of why it does not matter.
That's what I'm responding to. I'm explaining why it doesn't matter with this example which is what you asked about.