EFFECTS OF ACUTE AND CHRONIC 

 THERMAL EXPOSURES ON THE EGGS OF 

 THREE HUDSON RIVER ANADROMOUS FISHES 



ROBERT L. KELLOGG, JAMES J. SALERNO, and DAVID L. LATIMER 

 Ecological Analysts, Incorporated, Middletown, New York 



ABSTRACT 



Atlantic tomcod, alewife, and striped bass eggs were tested for chronic and acute 

 tolerance to elevated temperatures to generate information on potential thermal 

 effects of power-plant operation. Upper lethal temperatures (TL50) for normal 

 hatching success were 26.5 C for alewife eggs, 26.3 C for striped bass eggs, and 

 6.6 C for Atlantic tomcod eggs. Thermal tolerance of eggs exposed to elevated 

 temperatures for 5 to 60 min increased with advancing stage of embryonic 

 development and decreased with lengthening exposure duration. The applica- 

 tions of the data to the assessment of the impact of power plants are discussed. 



One element of the assessment of the environmental impact of steam 

 electric power plants using once-through cooling is the evaluation of 

 the effects of temperature elevations on the embryonic development 

 of fish species. Developing fish eggs are exposed to elevated 

 temperatures in power-plant cooling waters for variable periods of 

 time. Exposures range from a few seconds or minutes, as in the case 

 of eggs entrained into the cooling water at the point of intake or 

 discharge, to several hours or days, as in the case of demersal eggs 

 spawned in the discharge area. 



A number of past investigations have considered the effects of 

 temperature elevations on fish embryos. Schubel and Koo (1976), 

 Schubel (1974), and Schubel and Auld (1974) examined the effects 

 of a variety of time— excess temperature histories on the eggs of four 

 estuarine fish species. Typical experimental thermal exposures 

 consisted of 5- to 15-min periods of constant elevated temperatures 

 followed by varying rates of cooling to within 1°C of ambient. 



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