True, but to be clear:

Limnology : oceanography :: Freshwater biologist : marine biologist

As a once practiced marine biologist, what the fuck do I call myself if I worked with salmon??

Yeah I took courses in limnology, cetology, comparative anatomy, phycology and microbiology (among many many others), they’re all under the marine biology umbrella.

It doesn’t stop being under water if it’s not salty water, you may as well say you don’t study mammals because you study whales.