euphotic zone during April (Fig. 4E). There was a significant difference
between the phosphate concentrations in the central YS and the coastal
area (Table 2).
The diapycnal nutrient flux was restrained by the development of
stratification during summer, and thus quite low concentrations of
surface nutrients were observed in the central area (Table 2 and
Fig. 4). The concentrations of nitrate (1.1 ± 0.8 μmol L−1, mean ± SD)
and phosphate (0.09 ± 0.04 μmol L−1, mean ± SD) in the euphotic
zone (~30 m) of the YSCWM area (n = 15) during the October cruise
were significantly lower than those in the coastal area (p b 0.01, n =
18) (Table 2).