Delayed metamorphosis and short-term food limitation reduce juvenile or adult fitness in a number of marine invertebrate species. In this study, we tested the ability of pollutant and salinity stress to bring about similar effects on juvenile or adult performance. Larvae of the polychaete Capitella sp. I were exposed to sublethal cadmium stress Žup to 2000 mg ly1. or salinity stress Ždown to 10‰. for 24 and 48 h at 23 8C. Following exposure, we induced surviving larvae to metamorphose and monitored the subsequent survival, growth, and reproductive output of juveniles reared under control conditions Žno added cadmium, 32‰ salinity.. Similarly, larvae of the gastropod Crepidula fornicata were exposed for 24 and 48 h to cadmium in seawater Žup to a nominal concentration of 20,000 mg ly1.. Surviving larvae were reared to metamorphic competence in the absence of cadmium, induced to metamorphose, and maintained under control conditions for an additional 5 days to monitor juvenile growth rates and survival. Exposing larvae of Capitella sp. I to low salinity Ž10–12‰. for 48 h generally did not affect adult fecundity, but stressing the larvae for as little as 24 h significantly reduced post-settlement survival and juvenile growth rates ŽP-0.05.. In contrast, exposing larvae of this species to cadmium for even 48 h had no significant effects on post-settlement survival or fecundity, and no consistent effect on mean juvenile growth rate. Similarly, cadmium exposure did not significantly affect mean juvenile growth rates for C. fornicata, even when larvae were severely stressed Ži.e., when larval mortality exceeded 50% during exposures.. We suggest that heavy metal stressors do not act through the same mechanism as the stresses of inadequate food supply, reduced salinity, and delayed metamorphosis. q2001 Elsevier Science B.V. All rights reserved