Belzelbub
Contributor
OK. That makes sense. I was thinking that you were implying that the temperature spike was leading to more gas in the water. This way makes much more sense.Think of it from the tissue perspective. Gases aren't a problem when they're dissolved, but become a problem when they come out of solution and form bubbles. If the ray's tissue is nearly saturated to start with, a temperature rise could trigger bubble formation.
Still, I would think that the spike would need to be fairly dramatic for this to be a problem. A more gradual temperature increase should be more like a gradual ascent. Water seems to be fairly resistant to rapid temperature changes, or more accurately, requires a lot of energy.