Looks like your rear shocks are leaking. Its a common thing with these cars according to most on here. I had this a few weeks ago and paid Renault about £110 for both rear shocks (you should change both at the same time, even if only one is leaking).
Apparently you can fit them yourself with no bother but I paid a garage about £30 to fit the pair.
It looks pretty bad, you'll probably start hearing a thud when you go over bumps.
Good luck with getting it sorted!