472 JENNISON 



rotary microtome. Sections were made transversely through the 

 column at the level of the gonads, which run longitudinally from the 

 basal disk to the bottom of the actinopharynx (Stephenson, 1928). 

 The sections were mounted on glass slides, stained with picro-indigo 

 carmine and basic fuchsin, and examined microscopically. 



Oocytes from each identifiable female were measured with a 

 calibrated ocular micrometer, after the method of Dunn (1975), to 

 assess female maturation over time at both sites. At least 50 

 gametogenic cells were measured from one section of each female. As 

 a correction for differences in the diameters of oocytes due to the 

 plane of the section, only cells having a distinct nucleolus were 

 included in the total. If fewer than 50 cells were present in the 

 section, all gametogenic cells were measured regardless of position. 

 Males were classified into arbitrary stages based on an assessment of 

 their gonadal maturity (Table 1). 



Reciprocal transplants of anemones were made between the 

 outfall and control sites on Nov. 17, 1975. Eight cages with 

 1.25-cm-mesh stainless-steel screen fronts, sides, and tops; masonite 

 floors; and neoprene mesh backs held together by nylon fishing line 

 were built. Sixty anemones collected from one clone in the control 

 area were distributed evenly among four cages. Two cages were hung 

 at zero tidal height at the power-plant intake structure (caged 

 experimental control group), and two were hung in the outfall canal 

 (transplants). Similar procedures were followed for four cages of 

 outfall animals. The cages were collected on Mar. 25, 1976, and the 

 anemones were analyzed histologically. 



RESULTS 



Anthopleura elegantissima at the Morro Bay control site repro- 

 duced sexually on an annual cycle (Fig. 2). Although the January 

 1974 control collections were anomalous and there were no females 

 in the samples again until July, it is clear that oocyte diameter 

 reached a peak in summer, followed by spawning between August 

 and September. No oocytes were visible again in prepared sections 

 until the end of December 1974, but they increased in size through 

 the spring and summer, and spawning occurred again in August 1975. 

 The third year followed this pattern, with oocytes first visible in 

 October and a gradual increase in diameter leading to spawning 

 between August and September 1976. 



In the power-plant thermal outfall at Morro Bay, distinct annual 

 cycles of gametogenesis and spawning were obtained (Fig. 3). No 

 gonads were found in the first samples collected (Feb. 4, 1974), but 



