Implications of sublethal contaminant exposure on the early life stages of striped bass (Morone saxatilis) in the San Francisco estuary

Eight years of field and laboratory investigations indicate that sublethal contaminant exposure is occurring in the early life stages of striped bass in the San Francisco Estuary. Chapter one of this dissertation provides clear evidence of maternal transfer of xenobiotics and adverse effects on larval striped bass in this estuary. Significant levels of polychlorinated biphenyls, polybrominated diphenyl ethers and pesticides were found in all egg samples from river-collected fish. Developmental changes previously unseen with standard methods were detected with a novel technique. Significant differences in yolk utilization, brain development, liver development and overall growth were observed between larvae from river-collected fish and controls. Chemical analysis, early life stage morphology and histopathological results suggest that contaminants found in the eggs may be causing endocrine disruption during the early larval stages adversely affecting growth, development and survival.; In chapter 2 we investigate habitat use in female striped bass for the purpose of relating it to contaminant exposure and transfer of contaminants from maternal fish to progeny. Habitat use, residence time and spawning migration over the life of female striped bass were investigated by applying otolith microchemistry techniques. Otoliths were analyzed for strontium/calcium (Sr/Ca) ratio using an electron-microprobe to determine salinity thus distinguishing freshwater, estuary, and marine habitat use. In addition, a subset of otoliths was subjected to Multi-Collector Laser Ablation Inductively Coupled Mass Spectrometry to verify electron probe findings and to gain additional elemental and isotopic data in order to refine spatial habitat use. The Sr/Ca data suggest a wide range of migratory patterns. In particular age of initial entry into the estuary differs among individuals before returning to freshwater presumably to spawn. Some fish reside in freshwater year-round, while others return to more saline habitats and make periodic migrations to freshwater. Thus, frequency of habitat shifts and residence times differs among fish, as well as over the lifetime of individual fish. Results from this investigation will be combined with contaminant and histological developmental analyses to better understand how bioaccumulation of contaminants occurs, and the effects they and habitat use have on fish populations in the San Francisco Estuary.