JPR Advance Access originally published online on February 2, 2006
Journal of Plankton Research 2006 28(3):313-324; doi:10.1093/plankt/fbi127
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Relationship between the bloom of Noctiluca scintillans and environmental factors in the coastal waters of Sagami Bay, Japan
1 Department of Ecological Engineering for Symbiosis, Faculty of Engineering, Soka University Tangi-Cho, Hachiouji, Tokyo 192–8577, Japan, 2 Mutsu Institute for Oceanography Japan Agency for Marine-Earth Science and Technology, 690 Kitasekine Sekine, Mutsu, Aomori 035–0022, Japan, 3 Department of Hydrographic Science, Faculty of Education and Human Sciences, Yokohama National University, Tokiwadai, Hoogaya-Ku, Yokohama 240–8501, Japan and 4 Faculty of Education, Soka University Tangi-Cho, Hachiouji, Tokyo 192–8577, Japan
* Corresponding Author: hmiyaguc{at}soka.ac.jp
Received March 25, 2005; accepted in principle January 15, 2006; accepted for publication January 30, 2006; published online February 2, 2006
Communicating editor: K.J. Flynn
In order to study the mechanism of the bloom formation of Noctiluca scintillans, the relationship between the variation in the abundance of N. scintillans and environmental factors was examined in the coastal waters of Sagami Bay, Japan. Hydrographic (temperature, salinity, water stability), biological (chlorophyll a concentration, zooplankton biomass) and meteorological (rainfall, wind velocity, wind direction) factors were investigated from 1997 to 2004. For all years, the abundance of N. scintillans started to increase from March and reached a maximum in spring between April and May. The abundance in 1997 and 2000 was relatively high compared to the other years while the abundance in 1998 and 2004 was relatively low. A stepwise multiple linear regression analysis showed that the wind direction and rainfall were significantly correlated with the variation in the abundance of N. scintillans. Our results suggest that bloom formation can be separated into a three-step process: (i) initial increase in the abundance of N. scintillans attributed to an increase in optimum hydrographic and biological factors, (ii) N. scintillans is then accumulated by convergence of seawater by the factors of low rainfall and wind and (iii) swarmer-effects suggested enhanced bloom formation. Accumulation is considered to be a key trigger in this process of the formation of large-scale blooms.
This paper was presented at Plankton Symposium III, held at Figuera da Foz, Portugal between 17 and 20 March 2005, under the auspices of the University of Coimbra and the University of Aveiro, and coordinated by Mário Jorge Pereira and Ulisses M. Azeiteiro.