mass spam

I have a blog at http://digidal.buildtolearn.net/
If you notice in both the September and August archives I have received comments on each and every one of my posts.
The problem is that these comments are totally random, out of the blue quotations from somewhere and then link to the site http://www.partypokeronline.org/
Since all of the comments left for 2 months of postings have been written at the same time, this concludes that its some sort of comment spam.
Is this a hole in WordPress? How can this be fixed. I don’t want idiots posting non-relevant comments that is ultimately spam.
Thanks.