SIGNIFICANCE OF TIMING AND MAGNITUDE IN THE HYDROGICAL AND BIOLOGICAL FEATURES AFFECTING PEAKS OF NOCTILUCA SCINTILLANS IN THE MARINE STATION OF THE SOUTH SEA, KOREA

Abstract

We investigated weekly abundances of a red-tide protozoan, Noctiluca scintillans, in the Marine station of the South Sea from 2001 to 2004, in order to identify the effects of biological, chemical and physical variables on the temporal dynamics of the species. These long-term investigations have revealed temporal patterns of seasonal periodicity with maximal abundances in May-September, and with a low but obvious peak in December/January during the study period. The timing and magnitude that the species showed maximal peaks, delayed from May/July in 2001 and 2002 to August/September in 2003 and 2004. The distinctive peaks of the species occurred commonly after the chl-a concentration increased in accompanied with the nitrate concentration. It was coincided with the variation of surface salinity in the marine station during the study period. Moreover, the highest abundance of N. scintillans was observed when the response of the species to the chlorophyll-a peak was under the temperature range of 15°C and 20°C in 2002. However, the first peak of N. scintillans in winter was not coincident with the variation of the chl-a concentration in 2003. It suggested that the high abundance of N. scintillans might stem from accumulation by drifting from oceanic waters, considering no relationships with nitrate and biological parameters. The enhanced abundances of N. scintillans were likely to be dominated by functional response to chlorophyll-a and accumulation by drifting in the Marine station of the South Sea from 2001 to 2004.