79 POTASSIUM AND CESIUM-137 IN BIRGUS LATRO les on vet at “as id. he res is mm 57) im rer im gh lly roportional amounts under changing conditions of precipitation andfertilization (Cole et al., 1959). However, at the second or higher trophic level, represented by Birgus, if any such relationship exists between the uptake of cesium andpotassium, it is masked by several unknown variables in the ecosystem. SUMMARY Radiocesium and stable potassium levels were determined in samples of muscle tissue of Birgus latro, the coconutcrab,collected at Rongelap Atoll, Marshall Islands, . during March and August, 1958, and March 1959, and at Utirik Atoll in March 1959. Levels of cesium-137 ranged between 731 d/m/g dry weight at Kabelle Island, Rongelap Atoll, and 28 d/m/g dry weight at Utirik Island, Utirik Atoll. deviation of 3.66. levels was found. No significant correlation between cesium-137 and potassium There was nosignificant difference in the average levels of cesium- 137 in crabs collected at different times at the sameisland. TaBLe I Potassium and cesium-137 in Birgus latro (coconut crab) muscle collected at Rongelap Atoll and Utirik Island, Utirik Atoll Kabelle Island 1 : * | Sample , Vin . (340 March 1958 (dry season) 35 36° 37 38 . ee els } ity August 1958 (wet season) lap ‘els nd ich ely 7 8 9 10 : 12 | March 1959 (dry season) 1 1; ; exive nts ap, Potassium dry weight dry weight d/m/g me/g 604 1 2 | 5 3 | S.D.= 85 /eK | | ' : 20489 au | 18594 13789 10447 15092 4.212 3.794 3.591 4.082 3.743 i 17.25 14.68 11.99 15.03 11.92 13.87 —- | | 17258 13440 17056 9741 24564 10519 | | | | | 4.930 3.480 3.807 4.308 3.946 3.660 Av. = 14.12. Av. = 15430 Av. = 4.022 S.D.= 2.02 SD.= 5474 S.D. = 0.424 619 Av. = 630 | Wet/dry —- 524s: 731 . | pmuec cst?» Av. = 13.14 Av. = 15682 Av. = 3.884 S.D.= 281 S.D.= 3966 S.D. = 0.252 324 645 | Cesium Unit 10.32 11.40 17.68 13.04 650 Av. = 475 S.D.= 150 | : | 661 438 454 325 i 13.28 426 349 * 410 437 Av. = 445 $.D.= 9 he :0n It Cesium-137 oo ore IS The average potassium value for all samples was 13.05 mg/g dry weight with a standard ° i 18546 4.470 12.64 22065 4.330 12.00 24217 5.140 11.76 27993 4.840 Av. = 12.28 Av. = 23205 Av. = 4,695 SD.= 047 S.D.= 3956 S.D. = 0,366