An actographic study of diel activity in the semelparous polychaeteNereis(Neanthes)virensSars in relation to the annual cycle of growth and reproduction

Abstract

Invertebrate Reproduction and Development, 35:2 (1 999) 141-1 45 Balaban, Philadelphia/Rehovot 0 168-8 170/99/$05.00 O 1999 BalabanPhotoperiod has a profound influence on the life cycle of Nereis (Neanthes) virens coordinating the transition from somatic growth to reproductive development. Here we report on a rapid method to characterize the diel component of the photoperiodic response and characterize the photoperiodic response curve. The diel emergence activity ofthe semelparous polychaete Nereis (Neanthes) virens Sars has been investigated by means of an automated actograph. Emergence events were recorded for every second of real time and the number of events per hour analyzed over periods of up to 5 consecutive days under a variety of photoregimes. There is a marked nocturnal pattern of activity. The number of excursions from the burrow system is high during the night reaching near zero shortly after dawn. Excursions from the burrow system during daylight hours were much less frequent. The total number of emergence events per 24h was significantly higher under LD 16:8 than under LD 8.16 even though the period of dark, when spontaneous emergence mainly occurs, was longer. The actographic records suggest that under LD 8:16 the feeding behaviour of the animals is substantially reduced compared with that observed under LD 16:8. A photoperiodic response curve has been obtained where there is a critical LD cycle around LD 1 1 : 12 and a progressive increase in emergence rate between LD 12:12 and LD 16:8. The mean number of emergence events per day is directly related to the duration of the photophase and inversely related to the scotophase duration although emergence mainly occurs during the night.

Seasonal variation in UVA light drives hormonal and behavioural changes in a marine annelid via a ciliary opsin

“…Changes in behavioral activity patterns across seasons have been documented for a variety of species. Strong examples of such changes are long distance migrations or diapause/hibernation 39 – 42 , but are also present as subtler differences 43 – 46 , including diel locomotor activity in the close nereidid relative Nereis virens 47 , 48 . We thus investigated Platynereis locomotion over the day/night cycle under different UVA light conditions.…”

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

“…This is made evident in the rhythms of foraging activity. Using an automated behaviour recording approach we have previously demonstrated that Nereis virens engages in short bouts of intensive foraging behaviour, the period of which can be maintained under free running conditions (Last et al, 1999) and is therefore an expression of true rhythmicity. The ongoing experiments in this area will be published in more detail elsewhere, but the emerging results are of importance to this review and typical data will be discussed in this context.…”

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.…”