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Previous studies have produced similar results concerning the growth rate of P.
elegans. Smidt (1951) proposed that new recruits grew rapidly and reached sexual
maturity within a few months and Gudmundsson (1985) suggested that the P. elegans
population at Cullercoats reached sexual maturity and bred at the end of their first
year. These results were supported by Anger et al. (1986). They found that for P.
elegans grown in the laboratory, the minimum time from metamorphosis to the first
hatching of offspring larvae (3 setiger stage) was 81 days and suggested that each
individual could produce 2 generations per year. These findings were supported by
the growth rate calculated from the mean sizes of the cohort settling during April/May
at Drum Sands which suggested that these individuals reached sexual maturity during
September, a period of less than 90 days.
New recruits in this study were classed as being 18-22 setigers. This is slightly larger
than the size quoted by other authors e.g., 11 setigers (Rasmussen, 1973) and 12-14
setigers (Hannerz, 1956), although it approximately corresponds to the size given by
Hempel (1957), i.e., 17-20 setigers. Since sampling was carried out monthly in the
present study, significant growth after settlement may have occurred before sampling
in May. This may explain why the new recruits reported at Drum Sands were larger
than observed in other areas. Although metamorphosis is not clearly defined in most
spionid polychaetes (Anger et al., 1986), most authors agree that it occurs when the
individuals are approximately 14-17 setigers (Hannerz, 1956; Hempel, 1957), i.e., at
or shortly after settlement. Therefore, the new recruits sampled during May 1997 in
the present study were probably post-metamorphic, young juveniles.
Rasmussen (1953), Gudmundsson (1985) and Wilson (1985) observed asexual
reproduction in P. elegans and Hobson and Green (1968) proposed that this species
reproduced almost exclusively by this method of propagation in Barnstable Harbor,
Massachusetts. Asexual reproduction in P. elegans occurs by fragmentation into
numerous pieces at any part of the worm's body (Rasmussen, 1953). The fragments
then remain in the parental tube for about eight days until each piece has developed
into a new individual. It is unlikely that this occurred at Drum Sands as a maximum
of only 2.03% of the population sampled showed signs of regeneration following
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