I don't, it came up months ago in a similar post to this one, and they had sources which I do not.

It might very well have been the latter part of what you said, marine life is overwhelmingly close to shore or other landmarks like reefs/wrecks/vents. When it is pumped out into open ocean the currents can fully reach and disperse it, with a fraction of marine life within the (reduced) zone in which the salts are toxic. It all came from the ocean, and despite the massive volumes that are desalinated, it's not a meaningful increase in concentration.