Solar radiation as a synchronizing factor of circadian and ultradian biological rhythms of planktonic communities

Abstract

The change in the intensity of glow of organisms in the coastal waters of the Crimea was considered. It is shown that the synchronizing factor for circadian and ultradian biological rhythms of planktonic communities is the change in the intensity of solar radiation when changing light and dark times of the day. The parameters of the main biological rhythms of planktonic communities, leading to a change in the glow intensity of planktonic communities, were found out by the method of decomposition in a Fourier series. It is shown that the change in the glow intensity of organisms with a period of 14 hours characterizes the circadian rhythms of the light and dark periods. Changes with a period of 4.7 and 2.8 hours are due to the ultradian endogenous rhythms of the plankton community, associated with the intensity of division of phytoplankton cells and the rate of their consumption by zooplankton. Calculations showed that the correlation coefficients between the measured values of the glow intensity of organisms and the calculated ones, taking into account the influence of the three main biological rhythms, is r = 0.906, which confirms the correctness of the accepted assumes.