Yes, I would not keep tissues stored in a glut solution. If it were my samples, I would rinse in a PBS or cacodylate buffer after fixation. This is similar to you just keeping the samples in sea water, but seawater contains many more salts & minerals than you need. And since the glut kills and preserves the coral, they are no longer in need of sea water. :wink:
Also, do not store in plain buffer for extended periods of time either, because of bacterial growth. After rinsing in buffer, they should be placed in 70% EtOH. How long before you send the specimens to the other guy? If just a day or two, buffer storage is fine, but any longer, store in alcohol.
Does he post-fix in osmium? If so, tell him if the samples are in alcohol. He will need to rinse it out before placing them in the osmium.
Are these for TEM or SEM?