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CSIRO Marine and Atmospheric Research
Past Seminars

Seminar Abstract

A circle map for a phytoplanktonic life cycle

It has been observed that imposed photoperiodic regimen alternating between on and off may greatly influence the temporal population dynamics of many short-lived organisms (such as phytoplankton) capable of exhibiting strong sensitivity to light. Here, I consider how such an individual’s life cycle may be represented by a circle map model composed of just two contiguous development stages that respond differently to a periodic stimulus. An analysis of the temporal dynamics generated is carried out and general conditions under which a population may achieve life cycle synchrony in exposure to an on-off periodic stimulus are determined. The model is adapted to the situation in which a (less sharply defined) diurnal light cycle between day and night occurs. Using development data obtained for the phytoplankton Thalassiosira pseudonana and mean daily irradiation intensities recorded over different months at the latitude of Oban (west coast of Scotland), the potential effect of seasonal change in daily irradiance on the synchronous dynamics of such a population is quantified.

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CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
Peter Oke, (Oceanographic seminars) CSIRO Marine Research (03) 6232 5387
Piers Dunstan, (Biological seminars) CSIRO Marine Research (03) 6232 5382
Katrina Nitschke, Antarctic Climate and Ecosystems CRC (03) 6226 2265 & IASOS, University of Tasmania (03) 6226 2509