INCORPORATION OF WATER-BORNE STRONTIUM INTO OTOLITHS AND ITS TURNOVERIN THE GOLDFISH CARASSIUS-AURATUS - EFFECTS OF STRONTIUM CONCENTRATIONS, TEMPERATURE, AND 17-BETA-ESTRADIOL

The incorporation and retention of water-borne strontium in otoliths ( asterisci and/or lapilli) were studied using the freshwater goldfish C arassius auratus. The effects of strontium concentrations, temperature , and 17beta-estradiol were examined using atomic absorption spectroph otometry and X-ray analysis. Water-borne strontium (0.1, 1.0, and 10.0 mg l-1) was incorporated into otoliths (asterisci) in a concentration -dependent manner after an 88-day exposure, but a high concentration o f 10.0 mg l-1 rather depressed the rate of incorporation. Similar resu lts were seen with Sr-Ca ratios in plasma and otoliths. The strontium incorporated into otoliths remained after 92 days in nonstrontium-enri ched water, while that in scales and ribs decreased. Otolith (lapillus ) Sr-Ca ratios distinctly differed between freshwater (Sr/Ca = 2.6 x 1 0(-3)- and diluted (1/9, 1/6, and 1/3) seawater (25 x 10(-3) on an ave rage)-reared groups, but no difference was found among the seawater gr oups. These ratios linearly increased with temperatures between 16 and 24-degrees-C in asterisci (r = 0.65). However, they somewhat decrease d at 28-degrees-C. A single administration of 17beta-estradiol resulte d in hypercalcemia and decreased strontium incorporation into the lapi llus but not in the asteriscus. The lapillus contained 12 times more s trontium than the asteriscus.