Yes, the creator of an original work does have copyright in the work by dint of creating it, unless he or she created it "for hire" for someone else (e.g. for an employer; or as commissioned by a client or customer). While you can enhance the protection afforded by copyright, this may not be cost effective for a start-up ongoing series; you'd need to pay the  fee to register each new issue as it comes out, creating an ongoing cost center. The enhancement to protection--mostly somewhat greater penalties for infringement--is likely not worthwhile. To strengthen your IP protection, add another type of IP as well: trademark. Assuming--as I do for purposes of this answer--that you have created some original characters, you can register those characters (or at least the main ones) as trademarks, too, and you can do this up to 6 months in advance of publication. Marvel Comics, for example, has trademarks in the Iron Man, Thor (their version; you can't trademark the original Norse god), Spider-man, etc. characters. There are fairly clear instructions for doing this, and good general trademark information on the U.S. Patent and Trademark Office (PTO) website. By trademarking, if you one day create other products using those characters, those products will be protected, too.