Factors influencing Sr/Ca ratios in otoliths of Girella elevata: an experimental investigation

The utility of Sr/Ca ratios in otoliths as indicators of thermal history in fish was investigated for juvenile Girella elevata . There was no direct relationship between ratios of Sr/Ca and temperature of the water, as has been assumed in many previous studies. Sr/Ca ratios did not decrease when water temperature was elevated from 19 to 28° C. Elevation of ambient Sr levels in the sea water caused a significant increase in Sr/Ca ratios in otoliths, and there was a detectable increase in Sr/Ca ratios in otoliths of some individuals fed an Sr-enriched diet. Multiple factors may influence natural Sr/Ca ratios in otoliths of juvenile G. elevata and their interactions make it difficult to interpret the chronology of conditions experienced by an individual fish during early life in the pelagic or benthic environment.