The influence of photoperiod on oocyte growth and its role in the control of the reproductive cycle of the polychaeteHarmothoe imbricata(L.)

Abstract

The date of spawning of the first of the two batches of oocytes produced by Harmothoe imbricata each year is known to be influenced by both temperature and day length conditions during the preceeding period of vitellogenesis, acting directly on the rate of oocyte growth. The influence of day length is shown to be in the form of a critical day length effect, with days of II h of daylight or more acting as long days and advancing the date of spawning. It is suggested that this critical day length effect serves to synchronize the spawning of the first cohort of oocytes, and it may also entrain an endogenous time sense underlying the reproductive cycle of this species.

A Two Phase Photoperiodic Response Controlling the Annual Gametogenic Cycle inHarmothoe imbricata(L.) (Polychaeta: Polynoidae)

“…Firstly, there was a shift in the critical photoperiod from between 11-12 hr in animals collected late October to between 10-11 hr in those animals collected mid November. The latter result is identical to that obtained in an earlier study by Garwood and Olive (1982). Animals in the former group had experienced an estimated 18 days at photoperiods below 11 hr light per day in the field, but were unable to respond to their subsequent transfer back to these photoperiodic conditions.…”

“…Previous investigations by Garwood and Olive (1982) found this critical photoperiod to lie between 10-11 hr per day. However, this change in the animals' response to the photoperiodic conditions is not effective immediately after the stabilisation of gametogenic processes.…”

“…growth of the vitellogenic oocytes, are also influenced by environmental conditions. There is a critical photoperiod, between 10 and 11 hr of light per day, above which oocyte growth is accelerated and the spawning date of the first cohort advanced (Garwood and Olive, 1982). This critical photoperiod is responsible for the synchronisation of the spawning of the first cohort during spring, hence it has been termed 'Critical Photoperiod spring' (CPs).…”

Dancing to the rhythms of geological time: the biorhythm capabilities of Polychaeta in a geological context

“…Photoperiodic responses play an important role in the control of sexual reproduction of Nereis virens Olive et al, 1998;Rees and Olive, 1999) and a number of other phylodocid polychaetes (Clark, 1988;Franke, 1986;Garwood, 1982). In addition to the transduction of photoperiodic information (relative duration of photophase and scotophase), there is also evidence of long-term circa-annual cycling (Olive, 1995) or at least the operation of long-period interval timing capability .…”

Preliminary evidences of circadian fan activity rhythm in <i>Sabella spallanzanii</i> (Gmelin, 1791) (Polychaeta: Sabellidae)

“…The entrainment of daily cycles in behaviour and physiology to different photoperiod lengths is of importance for polychaetes to regulate growth, reproduction and behaviour accordingly to seasons (e.g. Schiedges, 1979;Garwood and Olive, 1982;Last et al, 1999;Last et al, 2000;Giangrande et al, 2000;Last and Olive, 2004). In this study, the occurrence of an endogenous fan activity rhythm and its entrainment capability were studied in S. spallanzanii kept under laboratory constant darkness and in different artificial photoperiod regimes.…”