Dynamics of picocyanobacteria in the Seto Inland Sea (Japan) during summer

Abstract

Coupled with wind mixing, N- and P-nutrients were introduced to the surface layer twice in 1992 (19 July and after 30 July). A picocyanobacteria (PC) bloom (5 × 104 ml-1) occurred following the first mixing event, and a rapid decrease of this bloom seemed to be attributed to high abundance (>2 × 103 ml-1) of heterotrophic nanoflagellates (HNAN). The second mixing event did not induce a PC bloom despite high nutrient contentration, low abundance of HNAN (<2 × 103 ml-1) and optimum temperature for growth. It is suggested that Fe-deficiency was responsible for the lack of a PC bloom during the second mixing period. -from Authors