## 2 Oceanographic Setting  
The Newfoundland Basin lies on the southeastern Grand Banks of the Northwest Atlantic Ocean (Figure 1), a key area where the exchange between subpolar and subtropical gyres takes place. The Labrador Current brings southward flowing cold and freshwater, which is seasonally replaced by northward-flowing warm and salty water of the North Atlantic Current (NAC). These two powerful surface currents traverse on the west and east side of the Newfoundland Basin. The spatial interplay of these currents determines the SST and sea-surface salinity of the Basin. The Labrador Current is the continuation of the Western Greenland and Baffin Island currents, with average annual flow speeds of 25-35 cm/s [28]. The cold Labrador Current sweeps the entire northwest Atlantic continent tal margin (Figure 1) [1; 29]). In contrast, the NAC is the continuation of the Gulf Stream (e.g., [30]) that flows through the Newfoundland Basin and transports warm and salty water to the northeast Atlantic, typically the strongest between 42\({}^{\circ}\) and 39.5\({}^{\circ}\) W [31]. At the southeastern tip of the Grand Banks of Newfoundland, part of the NAC recirculates or continues in an eastward direction, while the remaining fraction turns northward. It is also a critical region where the modern Labrador Current and NAC frequently interact.  
The SST and salinity of the Northwest Atlantic Ocean, particularly in the Newfoundland Basin, greatly vary. The annual SSTs vary between 7\({}^{\circ}\) and 17.5 \({}^{\circ}\)C in the Newfoundland Basin. When the influence of the cold Labrador Current increases, the impact on the southeast Grand Banks of the northwestern edge of the Newfoundland Basin expands, and the SSTs significantly decrease (Figure 1). Conversely, when the influence of the warm and salty NAC increases, the SSTs on the southeastern edge of the Newfoundland Basin increase resulting in a decrease in temperatures between the eastern and western sides of the Basin. It can be seen that the sea-surface of the Newfoundland Basin is mainly affected by the warm and salty NAC in the summer, and the cold Labrador Current has a smaller range. Down-depth SST plot (Figure 2b) suggests that the temperature rapidly decreases to 7 \({}^{\circ}\)C at ~500 m in the west, whereas the 7 \({}^{\circ}\)C isotherm crops out on the southeastern Grand Banks reflecting the spatial extent of the Labrador Current. The spatial impact of the Labrador Current and North Atlantic Current is also demonstrated by the salinity gradient (Figure 2c) between the eastern and western Newfoundland Basin.  
Figure 1: General oceanographic features of the modern northwest Atlantic Ocean. The mean annual sea-surface temperature with 5 \({}^{\circ}\)C contour demarcates between the subpolar and subtropical gyres. The location of the cores used in this study is listed in Table 1. Note that “white star” denotes the location of core Hu90-08 (this study). The tabular box with the discontinuous line shows the location of Figure 2. GS = Gulf Stream; NAC = North Atlantic Current; EGC = East Greenland Current; WGC = West Greenland Current; LC = Labrador Current; SPG = Subpolar gyre; and STG = Subtropical gyre.  
Figure 2: **(a)** enlarged bathymic map of the SE Grand Banks, SW Labrador Sea, and Newfoundland Basin. The location of the published records of a few cores used in the study is shown by the yellow dots, whereas the position of the sediment core Hu9007-08 (this study) is shown by the red star. **(b)** sea-surface temperature distribution on the SE Grand Banks on the X-Y transect is shown in Figure 2a. **(c)** sea-surface salinity along the X-Y section, which demonstrates the low salinity Labrador Current (west), whereas the position of the North Atlantic Current is shown by the high salinity (east). Note LC = Labrador Current; GS = Gulf Stream; NAC = North Atlantic Current; FC = Flemish Cap; and FP = Flemish Pass. Figure 2b,c were plotted using the Ocean Data View software [32].