## 3 Results  
### Hydrological Conditions  
The salinity profiles showed high variation during the four sampling cruises (Figure 2a-d), which was influenced by both the China Coastal water (CCW) and Kuroshio water (KW) in the study area. The observed salinity curves during the June 2018 and March 2019 cruises were similar to KW (Figure 2a,c). The salinity curves showed a wide variation and were mostly closed to the CCW curve during the September cruise in 2018 (Figure 2b). Most stations showed the salinity curve close to the CCW salinity curve, except station S5 which was weakly affected by the KW during the June cruise in 2019 (Figure 2d).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Station** & **Longitude (E)** & **Latitude (N)** & **Seabed Depth** & **Grouping** \\ \hline St 1 & 24\({}^{\circ}\)53.42\({}^{\prime}\) & 122\({}^{\circ}\)01.17\({}^{\prime}\) & 454 & DZ \\ St 10 & 24\({}^{\circ}\)50.46\({}^{\prime}\) & 121\({}^{\circ}\)59.40\({}^{\prime}\) & 210 & MZ \\ St 12 & 24\({}^{\circ}\)52.33\({}^{\prime}\) & 121\({}^{\circ}\)55.90\({}^{\prime}\) & 130 & SZ \\ St 15 & 24\({}^{\circ}\)48.01\({}^{\prime}\) & 121\({}^{\circ}\)56.45\({}^{\prime}\) & 273 & MZ \\ St Ex1 & 24\({}^{\circ}\)50.57\({}^{\prime}\) & 121\({}^{\circ}\)58.02\({}^{\prime}\) & 123 & SZ \\ St Ex2 & 24\({}^{\circ}\)49.81\({}^{\prime}\) & 121\({}^{\circ}\)57.75\({}^{\prime}\) & 156 & SZ \\ St S1 & 24\({}^{\circ}\)50.06\({}^{\prime}\) & 121\({}^{\circ}\)54.92\({}^{\prime}\) & 167 & SZ \\ St S2 & 24\({}^{\circ}\)49.67\({}^{\prime}\) & 121\({}^{\circ}\)57.16\({}^{\prime}\) & 57 & SZ \\ St S3 & 24\({}^{\circ}\)49.93\({}^{\prime}\) & 122\({}^{\circ}\)00.25\({}^{\prime}\) & 288 & MZ \\ St S4 & 24\({}^{\circ}\)50.10\({}^{\prime}\) & 122\({}^{\circ}\)04.08\({}^{\prime}\) & 674 & DZ \\ St S4-1 & 24\({}^{\circ}\)50.09\({}^{\prime}\) & 122\({}^{\circ}\)09.64\({}^{\prime}\) & 536 & DZ \\ St S5 & 24\({}^{\circ}\)50.06\({}^{\prime}\) & 122\({}^{\circ}\)13.25\({}^{\prime}\) & 878 & DZ \\ \hline \hline \end{tabular}
\end{table}
Table 1: Location and depth of sampling stations in waters off northeastern Taiwan, SZ = shallow depth zone (<200 m), MZ = middle depth zone (200–400 m), DZ = deep depth zone (>400 m).  
Figure 2: Salinity profile above 50 meters depth recorded at each sampling station. Data referred to 2018 in June (above 30 m depth) (**a**), September (**b**); and 2019 in March (**c**), June (**d**). The temperature (T) and salinity (S) diagram shows the distribution of averaged values of surface water (above the 10 m depth) of each sampling stations during all cruises (**e**). Two reference temperature–salinity curves were recorded from cruise OR1 618 between 15 July and 29 July 2001; the blue and red solid lines of T-S curves indicating the CCW (plume of Yangtze River; 30\({}^{\circ}\)30\({}^{\prime}\) N 122\({}^{\circ}\)52\({}^{\prime}\) E) and KW (Kuroshio water; 25\({}^{\circ}\)10\({}^{\prime}\) N 123\({}^{\circ}\)10\({}^{\prime}\) E) (adopted from [PERSON] et al. [30]), respectively.  
Figure 2e shows at 5 m depth the correlation between salinity and temperature. The averaged surface seawater temperature (SST) was highest in September 2018 with values 27.87 \(\pm\) 0.65 \({}^{\circ}\)C (mean \(\pm\) standard deviation). During this cruise, SST varied from 26.39 \({}^{\circ}\)C to 28.55 \({}^{\circ}\)C, while the average sea surface salinity (SSS) was only 33.53 \(\pm\) 0.16 PSU which was the lowest of all sampling cruises. During the cruises in June 2018 and June 2019, the average SST was 26.35 \(\pm\) 0.48 \({}^{\circ}\)C and 27.14 \(\pm\) 0.39 \({}^{\circ}\)C and the average SSS was 34.47 \(\pm\) 0.03 PSU and 33.88 \(\pm\) 0.10 PSU, respectively. The lowest average SST was 24.14 \(\pm\) 0.57 \({}^{\circ}\)C, recorded during the cruise in March 2019, with the highest average SSS 34.61 \(\pm\) 0.03 PSU. The SST limit was 23.61 to 25.21 \({}^{\circ}\)C in March 2019. The average SST and salinity were significantly different among the four sampling cruises (\(p\) < 0.01, one-way ANOVA).