Ianal, but I think ddg could come back and claim that their service doesn't copy the content or that their abstract is fair use, so a dmca wouldn't apply to them.
If that happens I'd use language about the exclusive "public display" right that you have over your work.
I'm not aware of this claim being used for a dmca, but I'd like to see how such a claim turned out.
IANAL either, but the DMCA has been used (by the RIAA, MPAA, and friends) to takedown pirate content on Google. I’d assume the same arguments would apply here. It can’t hurt to try.
Linking to a site that infringes copyrights may make the linker liable on the grounds that they are committing contributory copyright infringement. It's cheaper for search engines to delist sites than fight that battle--particularly if their corporate masters also rely on licensing media for distribution themselves.
If that happens I'd use language about the exclusive "public display" right that you have over your work.
I'm not aware of this claim being used for a dmca, but I'd like to see how such a claim turned out.