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INFLUENCE OF LARVAL EXPOSURE TO SALINITY AND CADMIUM STRESS ON JUVENILE PERFORMANCE OF TWO MARINE INVERTEBRATES, CAPITELLA SP I AND CREPIDULA FORNICATA
Citation:
Pechenik, J. A., T R. Gleason, D. Daniels, AND D M. Champlin. INFLUENCE OF LARVAL EXPOSURE TO SALINITY AND CADMIUM STRESS ON JUVENILE PERFORMANCE OF TWO MARINE INVERTEBRATES, CAPITELLA SP I AND CREPIDULA FORNICATA. JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY 264(1):101-114, (2001).
Description:
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 (up to 2000 g 1-1) or salinity stress (down to 10 ppt) for 24 and 48 h at 23 ?C. Following exposure, we induced surviving larvae to metamorphose and monitored the subsequent survival, growth, and reproductive output of juveniles reared under control conditions (no added cadmium, 32 ppt salinity). Similarly, larvae of the gastropod Crepidula fornicata were exposed for 24 and 48 h to cadmium in seawater (up to a nominal concentration of 20,000 g 1-1). 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 (10- 12 ppt) for 48 h generally did not affect adult fecundity, but stressed the larvae for as little as 24 h significantly reduced post-settlement survival and juvenile growth rates (P < 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 (i.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.