Influence of seawater temperature on phytoplankton growth in Jiaozhou Bay, China

Abstract

The phytoplankton reproduction capacity (PRC), as a new concept regarding chlorophyll-a and primary production (PP) is described.PRC is different fromPP, carbon assimilation number (CAN) or photosynthetic rate (P B). PRC quantifies phytoplankton growth with a special consideration of the effect of seawater temperature. Observation data in Jiazhou Bay, Qingdao, China, collected from May 1991 to February 1994 were used to analyze the horizontal distribution and seasonal variation of thePRC in Jiaozhou Bay in order to determine the characteristics, dynamic cycles and trends of phytoplankton growth in Jiaozhou Bay; and to develop a corresponding dynamic model of seawater temperature vs.PRC. Simulation curves showed that seawater temperature has a dual function of limiting and enhancingPRC. PRC’s periodicity and fluctuation are similar to those of the seawater temperature. Nutrient silicon in Jiaozhou Bay satisfies phytoplankton growth from June 7 to November 3. When nutrients N, P and Si satisfy the phytoplankton growth and solar irradiation is sufficient, thePRC would reflect the influence of seawater temperature on phytoplankton growth. Moreover, the result quantitatively explains the scenario of one-peak or two-peak phytoplankton reproduction in Jiaozhou Bay, and also quantitatively elucidates the internal mechanism of the one- or two-peak phyto-plankton reproduction in the global marine areas.