PECHENIK, J.A.; Tufts University, Medford, MA: Larval experience and carryover effects�metamorphosis is not a new beginning

For many years ecologists have documented the variation inherent in natural systems�e.g., variability in growth rates, fecundities, time to reproductive maturity, mortality rates, the outcomes of competitive interactions, and tolerance to pollutants. Over the past 20 years, it has become increasingly apparent that at least some of this variation may be caused by differences in embryonic or larval experience. Such experiences may include short term starvation or salinity stress, exposure to sublethal concentrations of pollutants or UV irradiation, and delayed metamorphosis. Carryover effects�effects that have their origins in early development but that are first exhibited only after metamorphosis�have now been documented in gastropods, bivalves, echinoderms, polychaetes, crustaceans, bryozoans, urochordates, and chordates. The extent to which carryover effects alter ecological outcomes in natural field populations, and the mechanisms through which carryover effects are mediated are largely unexplored.