Burrowing activity was utilized as a measure of the ability of the hard shell clam(Mercenaria mercenaria)and the Atlantic surf clam(Spisula solidissima)to cope with extremes of temperature and dissolved oxygen. Clams were removed from clean sand substrate and the progress of reburial timed. Experiments were conducted in a once through circulating seawater system in which temperatures were maintained at selected(?T)increments above ambient levels.