Environmental conditions (temperature, salinity, nitrate concentration, chlorophyll-a concentration, and C:N ratio) differed significantly among the classes (ANOVA, p < 0.01; Fig. 6). The temperature was lower in class I (mean ± SD: 10.1 ± 2.0°C) and III (12.7 ± 6.0°C) than in classes II (20.1 ± 4.9°C) and IV (24.0 ± 2.6°C) (Fig. 6a). Significant differences in temperature were discerned (p < 0.003, pairwise test with Tukey–Kramer adjacent) among different classes, except between classes I and III (p = 0.44). The only significant difference in salinity among the classes was discerned between classes II (33.76 ± 0.79) and III (34.27 ± 0.18) (p = 0.01, pairwise test with Tukey–Kramer adjacent) (Fig. 6b). The mean salinity with SD of classes I and IV were 33.99 ± 0.06 and 33.91 ± 0.36, respectively (Fig. 6b). The mean nitrate concentration values were high in classes I (4.20 ± 1.31 µM) and III (3.88 ± 3.86 µM), lower in class II (0.51 ± 1.31 µM), and the lowest in class IV (0.05 ± 0.01 µM) (Fig. 6c). The chlorophyll-a concentrations were significantly different among the classes (ANOVA, degrees of freedom [DF] = 3, F-value = 2.643, p = 0.048). However, no significant differences were identified among the pairs (p > 0.058). In particular, the chlorophyll-a concentration was the highest in class IV (0.69 ± 1.33 µg L-1), followed by class I (0.61 ± 0.23 µg L-1), class III (0.58 ± 0.37 µg L-1), and the lowest in class II (0.44 ± 0.48 µg L-1) (Fig. 6d]. Moreover, a high C:N ratio was identified in class IV (7.06 ± 1.50 mol mol-1), which was significantly higher (p < 0.01, pairwise test with Tukey–Kramer adjacent) than in classes II (6.13 ± 1.39 mol mol-1) and III (5.12 ± 1.22 mol mol-1). However, the C:N ratio in class IV did not differ from that in class I (6.05 ± 0.58 mol mol-1) (Fig. 6e).