Community successions have been documented over 2,000 years, during which time there were several temporary extinctions. The number of known chemosynthetic communities in the Gulf of Mexico now exceeds 40, ranging in depth from a few hundred meters to 3,000 m. Communities can change rapidly over distances of only a few meters. The levels of natural oil and gas seepage in the Gulf is great. Some surface slicks coincide well with known positions of chemosynthetic communities. The types of data received during geophysical surveys may be used to allow researchers to make educated guesses about the locations of chemosynthetic communities.
Mussel communities can be short-lived.
Studies have shown that accumulations of dead mussel shells can be no older than 15 - 20 years old. But photographs of some sites show little variation in living mussels and tube worms from year to year. More research is needed to determine rates of change and levels of variation. Naturally-occuring anoxic brine pools have been discovered which can kill fish but fuel surrounding mussel beds with gas. Mussels which fall into the pool soon die because the pools are far saltier than ambient water and some are much warmer.