Too many internal links to WP Mediathek

Not quite sure whether this is a problem of the theme or not.

Almost every post on my website creates unnatural internal links (abt. 200/post) to different photos in the Mediathek which are not included in the blog post as well as to different posts, archiv posts etc. The links are created automatically. I realized that when checking Google Webmaster Tools.

Could this be a theme problem? If not, would you please point me in the right direction as I couldn't find any info on that.
Thanks very much in advance for your help.

I am using Mantle Theme.

Sibylle