In earlier studies it was found that metamorphosis-inducing activity brings about the settlement of swimming trochophore larvae of the marine worm Capitella capitata. Such activity was attributable to alkylphenols, which are present in marine sediments as well as in hemolymph and embryos of the lobster Homarus americanus. These samples were taken from Long Island Sound and Vineyard Sound. Little or none of this activity was found in offshore lobsters taken from the edge of the continental shelf far from human influence. A comprehensive analytical method based on organic solvent microwave-assisted extraction, followed by solid phase extraction and gas chromatography-mass spectrometry was developed for the simultaneous identification and quantification of bioactive compounds. These compounds include the following four alkylphenols: #1: 2-t-butyl4-(diniediylberizyl)pheriol; #2:2,6-bis-(t-butyl)-4-(dimethylbenzyl)phenol; #3: 2,4-bis-(dimethylbenzyl)phenol; and #4: 2,4-bis-(diniethlybenzyl)-6-t-butylphenol. It is reported that 95 (36%) of 262 inshore lobsters contained one or more alkylphenols with average values as follows: compound #1, 11.2 +/- 55.9 ng/mL; #2, 23.3 +/- 355.9 ng/mL; #3, 116.6 +/- 434.2 ng/mL; and #4, 107.1 +/- 1167.9 ng/mL, respectively. Only one of 15 offshore lobsters (6.7%), had detectable alkylphenols. Three of five (60%) of deep-sea lobsters had embryos that were carrying higher levels of alkylphenols. These results suggest that inshore lobsters at higher water temperatures are exposed to alkylphenol contamination. Offshore lobsters at lower temperatures appear to be remediated and have lower alkylphenol levels in their blood by having remained offshore, presumably in less contaminated waters. The embryos were most likely formed during inshore reproductive maturation because offshore temperatures are too low for ovarian and egg maturation. These embryos remained contaminated because of their isolation within a relatively impervious shell.