Interesting reading. I always wondered whether turtles truly were more social than other species. Keeping a couple of herps myself it has always been hammered in from day one "keep them alone, they are antisocial and stress each other out even when they don't fight", but turtles always seemed exempt from that.
It's not surprising that the noise vibration affects them so badly, there is currently a huge debate about the effect of underwater sonar and military testing. Mostly on whales and dolphins but it's likely to affect everything. Especially that even species that cannot hear may still be affected by the vibration of the sound itself.
I enjoyed reading about freshwater turtles as well, all the conservation stuff you usually hear about is sea turtles. Thank you for sharing, I love reptiles and I really hope this information helps us protect them.