JOHNSON EFFECTS OF TEMPERATURE AND SALINITY ON ACAItll\ CAUFORNIENSIS EGGS 



increasing time as observed by Kasahara, Uye, 

 and Onbe ( 1975). Successful repopulation is possi- 

 ble at any point in spring that daily mean salinity 

 is in excess of 10%i), which usually occurs in early 

 June. Production of resting eggs in the annual 

 cycle of A. californiensis is thus viewed as a 

 "leaky" population diapause that is consistent 

 with the opportunistic nature of estuarine copepod 

 species. 



It is possible that the leaky character of the 

 diapause is retained because of the occasional suc- 

 cess of the early-hatching portion of the popula- 

 tion in years with early termination of winter 

 rains. In those years, this fraction of the popula- 

 tion would be strongly favored by the end of the 

 growing season because of its early start. In years 

 with prolonged spring rains, the late-hatching 

 fraction would be favored. Variations in the 

 weather cycle, thus, may prevent development of 

 absolute and restrictive requirements for termi- 

 nation of diapause. 



ACKNOWLEDGMENTS 



I wish to thank Charles B. Miller for the invalu- 

 able assistance provided in discussions of the 

 experimental results and in reviewing the manu- 

 script. Special thanks are also due Abraham 

 Fleminger and Peter Sertic for their aid in resolv- 

 ing the taxononiic status of Acartia populations 

 from Los Penasquitos Lagoon, La Jolla, Calif, and 

 upper Yaquina Bay. 



This research was supported by the Oregon 

 State University Sea Grant College Program, 

 under the Office of Sea Grant (NOAA), #04-6- 

 1,58-44094. 



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