Fig. 3
The results of PCA of the seven oceanographic factors: temperature (Temp10, °C), salinity (Sal10, psu) and DO (dissolved oxygen; DO10, ml/L) as measured at a depth of 10 m; and the mixing index of temperature (Temp1050, °C), salinity (Sal1050, psu), and DO (dissolved oxygen; DO1050, ml/L) for the difference between 10 m and 50 m depth layer (Sal1050, psu), and zooplankton biomass (Zoop, Log10 mg/m3); in the East, West, and South Seas of Korea during April of 1985 and 2002, and June and August of 1985, 1995, and 2002. Proportion of explained variances for the 3 components (a), correlation for the variables in total (b), East Sea (c), and West Sea (d) during summer in 1985, 1995, and 2002