Do unpowered Subwoofers/Speaker effect room modes?

In my "small two channel" room I have two small powered subwoofers. Both are ported, one with two 6.5" woofers and the other with a single 6.5". These are part of a Computer system in which I mostly sit and peruse A'gon =). Neither have anything to do with the Audio rig. They are physically located under the desk on the opposite wall from the system.

I am attempting to apply various room treatments and I am wondering what effect these woofers may have on the them. Maybe some absorptive qualities? Could they effect room modes?

I read some on this topic a few years back. I recall that someone advocated that even the tiniest of speakers, like that in a phone receiver, could have a noticeable effect.

So before, I dig through a tangled web of computer cables, I humbly ask for your opinions.