ENVIRONMENTALLY-INDUCED VARIATION IN ELEMENTAL COMPOSITION OF RED DRUM (SCIAENOPS-OCELLATUS) OTOLITHS

Diet, temperature, and salinity were manipulated to determine their in fluence on magnesium, potassium, strontium, sodium, and calcium concen trations in sagittal otoliths of red drum, Sciaenops ocellatus, using an atomic absorption spectrophotometer and wavelength-dispersive elect ron microprobe. The experiments were designed to determine whether env ironmental history could be reconstructed from otolith microchemistry, and to assess the potential for confounding factors. No dietary effec t was detected on whole otolith elemental composition at a salinity of 30 parts per thousand, although an effect at very low salinities is e xpected. Levels of calcium, strontium, and potassium in whole otoliths were correlated with temperature, and sodium was correlated with sali nity. Despite highly significant correlations (P less than or equal to 0.01), there was a high degree of variation in concentrations of each element within individual otoliths, even though they were produced un der constant conditions. This suggests that precise reconstruction of environmental history for young red drum is impractical using otolith elemental composition.