9 87 



Kennedy, V. S. , W. H. Roosenburg , M. Castagna, and J. A. Mihursky. 1974. 



Meraenaria meraenaria (Mollusca: Bivalvia) : Temperature-time relationships 

 for survival of embryos and larvae. U.S. Dept. Commerce, Natl. Mar. Fish. 

 Serv. , Fish. Bull. 72(4) : 1160-1166. (essentially the same paper was 

 published under the same title in Mihursky et al. 1974, The thermal 

 requirements and tolerances of key estuarine organisms, q.v.). 



Cleavage stages, trochophore larvae, and straight-hinge veliger larvae were 

 exposed to 11 different temperatures (17 . 5-43. 1°C) for 8 different time 

 periods (1-360 min) . Mortality increased with temperature increase, and at 

 higher temperatures with increase in time exposure. Temperature tolerance 

 increased with age. Cleavage stages were most sensitive to higher 

 temperature, straight-hinge larvae least sensitive. By multiple regression 

 techniques, predictive equations were developed. In discussing results the 

 authors commented that little precise information exists on temperature 

 range for spawning, other than Carriker's observation that in Little Egg 

 Harbor, N.J. hard clams spawn between 22 and 30°C with maximum frequency 

 between 24 and 26°C. - J.L.M. 



988 



Kennedy, V. S., W. H. Roosenburg, M. Castagna, and J. A. Mihursky. 1974. 



Meraenaria meraenaria (Mollusca: Bivalvia): Temperature-time relationships 

 for survival of embryos and larvae. In The Thermal Requirements and 

 Tolerances of Key Estuarine Organisms. J. A. Mihursky et al. Univ. Md. , 

 Center for Envir. and Estuar. Research, Prince Frederick, Md. , N.R.I. Ref. 

 No. 74-132: 101-124. 



This is the manuscript of an almost identical paper published in U.S. Dept. 

 Commerce, NOAA, Fish. Bull. 72(4): 1160-1166. 1974. The abstract reads: To 

 estimate the effects of entrainment of Meraenaria meraenaria embryos and 

 larvae in the cooling water systems of steam-electric power plants, we used 

 a thermal gradient apparatus. Cleavage stages, trochophore larvae and 

 straight-hinge veliger larvae were subjected to 11 different temperatures 

 for 8 different time periods. There was a direct relationship of mortality 

 with increased temperature and at higher temperatures, with increased 

 exposure period. As the animals aged, temperature tolerance increased, with 

 cleavage stages most sensitive to higher temperature and straight-hinge 

 larvae least sensitive. Multiple regression analysis of percentage 

 mortality on temperature and time produced estimating equations that allow 

 prediction of percentage mortality under different temperature-time 

 combinations. Entrainment of M. meraenaria embryos and larvae in cooling 

 systems of power plants should be as short as possible to keep mortality to 

 a minimum. An original abstract under the listing of the published paper. 

 - J.L.M. 



989 



Kennish, Michael J. 1976. 



Monitoring thermal discharges: A natural method. Underwater Nat. 9(4): 8-11. 



Meraenaria meraenaria grows by secreting an increment of calcium carbonate 

 each day, 1 to 150 y thick, at outer shell margins. Thickness of the band 

 depends on water temperature. Microstructure of the shell therefore shows 

 a daily record of response to environmental variables, especially 

 temperature. At Barnegat Bay, N.J. in 1973, samples of quahog were 

 collected at 31 sites close to and remote from thermal effluent from a 

 power plant. In addition, more than 2,700 healthy clams, 20 to 65 mm high, 

 were collected from several N.J. estuaries, marked, and planted within the 

 influence of the effluent and at a control site, in 1974 and 1975. Live and 

 dead specimens of transplanted clams were collected at intervals during 1974 

 and 1975. Valves were sectioned, and acetate-peel replicas were made for 

 examination of microstructure. Results showed that M. meraenaria is an 

 excellent monitor of thermal discharges. Severe stress is exerted in summer, 

 when water temp is at a max. Daily growth increments are reduced by 10 to 

 30% within influence of the plume as compared with clams at control sites. 



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