Your implied copyright runs under your real name as well as any other monikers you would use. If you sign your pics with Envoken it is “understood” to be swappable with your real name. Same difference.
Copyright laws (in the States) take effect the minute you “save” your artwork to your harddrive. That is considered published. Personally, if I feel uncomfortable, I go ahead and spend the $30 bucks to get a cert of copyright (the certification allows you to list all artist names applicable to the piece)
It is incredibly important to understand one thing about copyrights. They are only as powerful as the amount of effort YOU are willing to put behind the label.
Copyright infringement happens EVERYDAY, particularly on the internet and the international scene. You either accept it or spend BIG $$ fighting it. You have to be willing to back that little “c”. The law will not stand in your stead.
Here’s the link to the US Copyright office:
http://www.loc.gov/copyright/
If you need further info or explanation let me know. I have about 30 copyright certs. hee hee. Probably not worth the paper they are on, but they look cool!

BTW: I don’t have alot of fear/respect for watermarks. I’ve got Maya PLE and am quite able to “eliminate” the watermark in postproduction in Photoshop! (Thanks Adobe!!!)