Not sure if you can do this or not but have you tried selecting the edge loop and doing a detach surface?
One sure way to do it but probably not the best or quickest would be to cut the sphere in half (cut face, detach faces, etc - whatever you prefer) and then only merge the vertices on the half that's not going to be opened.
I'm not skilled with UV's yet so I don't know if or how they'll be effected.
Don't be satisfied with what you can do but rather strive to do the things you can't do!
Exceed Expectations!