Short answer no. Whois will give you a match to who actually owns the address. Company name, contact info for the owning entity, etc.
If you are an admin on the particular site, you can track the IP back to a username that used it. Most IP addresses are assigned to large providers and in turn assigned to a user for a particular internet session. Not many ip addresses actually belong to an individual person any longer. For example: I'm an admin on a business related site and my username has 37 different addresses associated with it on that site. It just depends on what address is available from Verizon's pool of allocated addresses when I log onto the net.
More specific to your question, if you are a member, registered on that site with that username, contact an administrator on the site. They can look at the login info and see what is what. Probably a good idea to change your password as a registered member.
If you are not registered and someone else has that username, well that's the way it is.