Regarding fish, as flow decreases in the river, temperature rises, and the hotter water is, the worse it is at retaining oxygen. So all cold water fish are dead because they cant survive in hot water period, and all large active fish basically suffocate, and all the fish that rely on those for food starve and/or suffocate.
To illustrate how severe the issue is, I moved to Washington to fish the Puget Sound steelhead / salmon runs.
Global warming has basically made the rivers emptying into the sound hostile to life. So the fishing is shut down indefinitely in the hopes that somehow the salmon/steelhead will magically adapt. On top of which, the rising temperatures are taking seasonal algae blooms in the sound and super charging them, meaning even less oxygen for fish/crabs.
Diggity double fucked am I.