According to Osurac :
Thanks everyone for your input, unfortunately that is the only picture
I have at the time. I may have another one in a week or so, I just
wanted to make sure it was a major issue that I should get fixed.

Or, just look at the picture yourself, and let us know whether
there's another joist behind the cut one, and approximately
how far away from the cut one it is.

To me it looks like another joist with a bit of pressure treated
lumber on the bottom. Eg: a sill plate.

Even if it is another joist (and probably not absolutely neccessary
structurally), I really don't like arbitrarily severed joists, and
it may give you problems with the toilet later on due to flex.

If it's what I think it is, a 6' or more piece of joist laminated on the
backside (I _assume_ the pipe won't interfere on that side), with
proper nail cleating would do the trick. If the cut joist has
dipped, you'll want to push it up a bit to get it back in line
before cleating in the sister.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.