Why is cold water better at dissolving oxygen? Is the same true of the atmosphere?

I’m asking this question here because I’m not even sure how I would begin to start checking Google for this

And this does assume that what I’m asking is true, but I definitely remember hearing somewhere that oxygen is more easily dissolved in colder water, and that this is part of a reason why things can get very big in the Antarctic and Arctic seas.

I guess where my head is at is thinking about how oxygen is dissolved into the atmosphere by plants, and wondering if that’s sort of can be a feedback loop in some small way. Or if one can affect the other, maybe not necessarily a feedback loop.

Best wishes,

John, science nerd but not scientist, 38, Wisconsin