FISHERY BULLETIN: VOL. 80, NO. 4 



ing in Nereis virens with an artificial rise in tem- 

 perature from ambient (5°C) to 22°C over a 10-h 

 period. 



The specific environmental signals required to 

 initiate spawning may be associated with the 

 phase of the moon and the stage of tide. Our obser- 

 vations of initial spawning activity shortly after 

 full moon are in partial agreement with Pettibone 

 ( 1963) who reported that the spawning activity of 

 Nereis virens on the New England coast centered 

 around both full and new moon. Brafield and 

 Chapman (1967), Bass and Brafield (1972), and 

 Snow and Marsden (1974) have reported that 

 swarming coincided with the time of new moon. 

 The sandworms at Wiscasset spawn during the 

 second half of the outgoing tide through the first 

 part of the incoming tide. Pettibone (1963) re- 

 ported similar observations from Barnstable, 

 Mass. Bass and Brafield (1972) reported swarm- 

 ing in the Thames population only during periods 

 of day and night high tides. Our only observation 

 of some exceptionally large Nereis virens swarm- 

 ing at high water occurred in the Damariscotta 

 River, Maine, in the vicinity of Fort Island (lat. 

 43°53'30" N, long. 69°31'30" W). 



Spawning Characteristics 



Some of the characteristics of spawning Nereis 



virens recorded by different investigators are 

 summarized in Table 3. 



Nereis virens has been described as atokous 

 (Brafield and Chapman 1967; Snow and Marsden 

 1974) and epitokous (Gustafson 1953; Sveshnikov 

 1955; Khlebovich 1963). Clark (1961) reported 

 that the structural modification associated with 

 epitoky may be subtle and consist only of an elon- 

 gation of the setae, modification of the sense 

 organs, and reconstruction of the musculature. 

 According to this description, spawning individ- 

 uals captured in the vicinity of Wiscasset were 

 obviously epitokes; the same morphological 

 changes recorded in England by Bass and Bra- 

 field (1972) for adult males were observed in the 

 Wiscasset population. There is no reason to doubt 

 that Nereis virens display different reproductive 

 characteristics in different geographical loca- 

 tions. Dales (1950) reported that nereids are well 

 known for displaying variable reproductive 

 habits within a given species. 



ACKNOWLEDGMENTS 



We extend our appreciation to Clement Walton 

 and Christy Adams for their assistance in the 

 collection of data used in this research. Special 

 thanks are also due to David Sampson for assist- 

 ance in the analysis of data, James Rollins for 



Table 3. — Some characteristics of spawning Nereis virens recorded by different investigators. 



742 



