480 JENNISON 



In the Morro Bay control populations, female spawning also 

 occurs during periods of maximum temperature, but not with the 

 same timing exhibited by anemones in the outfaill. Spawning took 

 place in the control samples during periods of mean temperatures 

 between 14 and 16° C, but it did not occur until a month aifter these 

 temperatures had been reached. In 1974 and 1975, these tempera- 

 tures were reached in June, but spawning did not occur until July. In 

 1976, these temperatures were reached in July, and the population 

 did not spawn until September. A similar spawning pattern was seen 

 by Ford (1964) in populations from Marin County and by Jennison 

 (1977) in Sonoma County, California. 



Despite the significant temperature differences between outfall 

 and control areas, we see the same general pattern of a winter 

 temperature decline and a summer increase at both sites. If anemones 

 time their reproductive events by temperature cues, it is likely that a 

 predictable pattern of temperature change would be more important 

 than the absolute temperature level (Giese and Pearse, 1974). 

 Galtsoff (1961) observed that different physiological races of the 

 same species may spawn at different temperatures. Outfall anemones, 

 although not necessarily of a different race than those in the control, 

 may, nevertheless, be acclimated to the warm-water regime in which 

 they are found. Possibly they are responding at 25° C to the same 

 cues that affect the control animals at 15°C. The difference in 

 response time (2 weeks in the outfall to 1 month in the control) may 

 be simply a function of the more rapid metabolic rate of outfall 

 anemones caused by the higher absolute temperatures in which they 

 occur. The delay in spawning of outfall females in 1976 might have 

 resulted from the gradual rise in temperature, which permitted a 

 period of metabolic accommodation. Thus the precipitous spawning 

 that was observed in 1974 and 1975, when the temperature 

 threshold was reached abruptly, did not occur. 



Males of A. elegantissima at the Morro Bay control site develop 

 over an annual time course similar to that of the females, with early 

 gametogenic stages proliferating in February and March, ripe sperm 

 apparent by April, and spawning occurring between August and 

 September in each of the 3 years studied (Fig. 4). Males in the 

 outfall, however, showed an abbreviated reproductive season, with 

 no early stages visible before April of each year. This appears to be 

 caused by the high temperatures in the outfall. Male development is 

 suppressed until late spring, possibly for metabolic reasons, but 

 sperm mature in outfall populations by May each year. It is not 

 unreasonable to assert that males of A. elegantissima can develop 

 quickly. Using autoradiography, Beeman (1970) determined that it 



