If they are gulping air at the surface then probably the CC are needing air. The only other thing I can think of is that they could be eating pellets if you have been feeding pellets. The last DO sag we had got our LMB cruising the shallow edge back and forth along the bank. I counted 63 of them in that one school just under the surface. I also saw CC fry at the surface in another area.
Dissovled oxygen levels are usually lowest early in the morning. Overcast skys and dead calm conditions with no wind compond the problem as do dead an dieing aquatic vegetation due recent muddy water or herbicide applications.
Is there a way you can run a hose to the pond and horizontally circulate the water? See Bruce's horizontal aeration thread, it is very informative and can be used in an emergency.
aeration simplified:
http://www.pondboss.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=22;t=000042 horizontal aeration:
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=11;t=000125;p=1
