This is very nice, Mike. I like the capture of the bubbles and you did a very nice job exposing for them. I do think if you wanted to go the extra mile you could select some of the smaller/darker bubbles and pull them up using levels or shadow/highlight.
Compositionally I wish the biggest bubbles were more to the bottom of the image but you can't move bubbles now can you? I think you did well by getting all bubbled inside the frame and not leaving any half in/half out.
I do find some of the tiniest specs a bit distracting and if you went to print this I think you'd see it there even more. You might use the healing brush or clone tool to dab those littlest specs out and leave just the ones that actually appear to be bubbles.
I love that you reduced your exposure to get the glare off the surface of the water. Nice work!
Jules:
Thanks for all the comments. After I posted last night, I actually started to clone out some of the smaller specs for the very reason you suggested -- they are a bit distracting!
I like this cleaned up version. Makes a better image. Nice rich colors and interesting shapes. Good job! It takes patience to find patterns in the (cold) ice.