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MP17 Endangered Species and Environmental Contaminants: Status of Science
(OST-1117-768672) Implications of sublethal contaminant exposure in early life stage striped bass.
Ostrach, D1, 1 University of California at Davis, Davis, CA, USA
ABSTRACT- The striped bass population in the San Francisco estuary has declined dramatically since the mid-1970s to the lowest population index recorded in 2004. This decline has been attributed to factors such as water diversions, climate, introduced species, starvation and contaminants. Morphometric and histological techniques and criteria were developed and used to assess the condition of striped bass larvae, Morone saxatilis, sampled from the estuary over an 8-year period. To evaluate the starvation hypothesis and to develop criteria necessary to determine the health of larvae in the field, laboratory nutritional experiments, bioassays using agricultural drain water and individual contaminant exposures were performed. Morphological and histological analyses performed in the laboratory allowed the distinction between fed larvae and those deprived of food. Over 3000 striped bass larvae collected from the estuary between 1988-1995 as well as experimental larvae were evaluated with the criteria developed in the laboratory. Field caught specimens did not appear similar to those of food deprived laboratory specimens and were in better condition than the fed specimens. However, field collected larvae exhibited abnormalities consistent with those found in response to sublethal exposure to xenobiotics and were similar to those found in bioassays of agricultural drain water and pesticides. No evidence for starvation was found in field collected larvae during all years studied. Results from field investigations and laboratory experiments suggest that starvation did not cause striped bass larvae mortality during this period. However, results indicate sublethal contaminant exposure of early life stage striped bass was occurring during all 8 years studied causing abnormalities that adversely affect subsequent survival.
Key words: larval striped bass, xenobiotic, morphometry, histopathology
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