virtually none, even though the clams had extended siphons which indicated 

 they were still active. At 21 to 25° loss was less rapid, but lasted for at 

 least 45 days, and was 27% of the original. Clams were exposed to doses of 

 radiation ranging from 186,656 to 5,833 roentgens. LD50 was reached in 5.5 

 days at the highest dose, 4.5 days at 163,324, 6.5 days at 139,992., 25.5 days 

 at 116,600, and 38.5 days at 93,328. At 46,664 to 5,833 roentgens there was 

 less than 50% mortality in 60 days. - J.L.M. 



1503 



Price, Thomas J. 1965. 



Accumulation of radionuclides by marine invertebrates. In Ann. Rept. Bu. 

 Comm. Fish. Radiobiol. Lab., Beaufort, N.C. for fiscal year ending June 30, 

 1964. U.S. Dept. Interior, Fish Wildl. Serv. , Bu. Comm. Fish. Circ. 217: 

 16-18. 



Mereenaria mereenaria was among several marine invertebrates exposed to 

 radionuclides.- Iodine-131 was accumulated rapidly at first, more slowly 

 after 10 days. After 28 days radioactivity was 10 times as great in clams 

 than in the surrounding water, and was still accumulating. Levels in oysters, 

 scallops and mussels were 10 times to 2 1/2 times as great in the same period. 

 Clams in a tank without substratum accumulated more radioactivity than clams 

 in a substratum, probably because sediments adsorbed some radioisotopes. 

 Hard clams were held in a zinc-65 solution for 5 days, then held in the 

 natural environment or in a laboratory tank of running seawater. After 177 

 days larger clams in both experiments had retained more of the original 

 activity than smaller clams. Retention was lower in laboratory tanks, 

 probably because the clams were unable to burrow, and thus had more body 

 surface exposed. More than one rate of retention of zinc-65 was observed. 

 - J.L.M. 



1504 



Price, Thomas J. 1965. 



Accumulation of radionuclides and the effects of radiation on molluscs. 

 In Biological Problems in Water Pollution, Third Seminar, Cincinnati, 

 13-17 Aug. 1962. Envir. Health Ser . , Water Supply and Poll. Contr., FS 

 2.300:WP-25: 202-210. 



Accumulation and retention of cesium-137, cerium-144, zinc-65, and gold-199, 

 and effects of radiation were followed on Mereenaria mereenaria and 2 other 

 bivalves. Over 20 days, uptake of Cs-137 by hard clams was fairly constant, 

 with little evidence of reaching a steady-state condition. Clams accumulated 

 more isotope than oysters. Loss rates also were studied. After 28 days 12% 

 of the isotope remained in hard clams. Ce-144 was taken up rapidly by clams, 

 with a strong inflection point before 4 days and maximum level of accumulation 

 after 20 days. Clam shells accumulated Ce-144 most rapidly and reached the 

 highest maximum; meats accumulated much smaller amounts, and liquor least. 

 Initial loss of Ce-144 was rapid during the 1st 45 days. After 195 days 20% 

 of original activity remained. Clams accumulated much less Zn-65 than 

 oysters. After about 22 days both species were still accumulating Zn-65 but 

 at a lower rate. Accumulation of Au-199 by hard clam was rapid for 14 days, 

 much slower thereafter. Live clams took up more activity than separated 

 shells. Under irradiation with cobalt-60 at various dosage rates up to a 

 maximum of 350,000 roentgens/hr, controls showed no mortality. LD50 rates 

 for hard clam were: 186,656 r - 5.5 days; 163,324 r - 4.5 days; 139,992 r - 

 6.5 days; 116,600 r - 25.5 days; 9 3,328 r - 38.5 days; at lower rates, 50% 

 mortality was not reached after 60 days. Accumulation of radionuclide was 

 little affected whether the activity was in the ionic or particulate state. 

 - J.L.M. 



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