## 3 Results
### Patterns of Primary Production and Nutrient Consumption Distribution
#### 3.2.2 Nutrient Consumption and Primary Production in Areas with High PP Values  
Region II. This area is located in the southwestern part of the sea (Figure 7). Through its water area, there is a flow of Atlantic waters into the Barents Sea. In addition, this area is located in the zone of the continental slope on the western border of the Barents Sea shelf. The depth difference here ranges from 200-500 m in the eastern part of the region and up to 2000-3000 m in its western part. The depth of the lower boundary of the euphotic layer is 50-80 m. In contrast to the Region I, in Region II, the largest NCPSi values are 50 g C m\({}^{-2}\) less (103 \(\pm\) 11 g C m\({}^{-2}\)). In addition, in this region, the difference between the highest values of NCPSi and NCPN (73 \(\pm\) 7 g C m\({}^{-2}\)) is not so large and is only about 30 g C m\({}^{-2}\) (Figure 9B). In this area, none of the studied nutrients are the limiting factor of photosynthesis. The residual reserve of nitrogen during the period of maximum development of the photosynthesis process is at the level of 25-30%, and phosphorus and silicon are at the level of 55-60% as can be seen this in Figure 9A (100% minus value of consumption). Apparently, in this area, there is an effect of the influence of the continental slope on the value of PP. A similar effect is given in works describing the enrichment of the euphotic layer with nutrients on the continental slope of Sakhalin and Kamchatka [2]. Region III. This area is located in the southeastern part of the Barents Sea, the waters of which are most affected by the flow of the Pechora River (Figure 7). The highest value of NCPSi in this area is 106 \(\pm\) 7 g C m\({}^{-2}\) and for new production 65 \(\pm\) 4 g C m\({}^{-2}\) (Figure 10B). In contrast to areas located in the zone of Atlantic waters, where the remaining stock of none of the studied nutrients reaches a critical value--limiting the course of photosynthesis, in this area, nitrogen can be such a limiting factor. During the period of maximum development of the photosynthesis process (August-September), the residual reserve of nitrogen is at the level of 10%, the largest value of its consumption is observed in August with amounts to 90 \(\pm\) 6%. The level of silicon consumption this month is 80 \(\pm\) 2%, and phosphorus is 70 \(\pm\) 6%. Figure 9: Annual cycle of primary production and nutrient consumption (**A**) and primary production (**B**) in Region II; (**A**) is the consumed part of the nutrient supply in the process of photosynthesis (blue: mineral phosphorus, red: mineral nitrogen, green: silicon); (**B**) primary production (green: NCPSi; red: NCPN). In the entire southeastern part of this area to Kolguev Island, the euphotic layer occupies the entire water column from the surface to the bottom, and in the deeper northwestern part, from 45 to 75 m. Another feature of this region, which affects the course of the photosynthesis process, is that, according to long-term average data, until May, almost the entire water area of this region is covered with ice (Figure 11). By May, the ice edge recedes to the east, but the entire southeastern part between the Novaya Zemlya archipelago and the coast of the mainland and from Kolguev Island to the Kara Gates is covered with ice [25]. Even in June, not all of the area is ice-free. As measured by phytoplankton studies in the area, even in the spread of light due to the ice cover, the start of the photosynthesis process in the spring does not stop. This effect was described in the works of employees of the Murmansk Marine Biological Institute [50]. The presented calculations in Figure 10A,B show that already in April, in the presence of a continuous ice cover, the consumption of nutrients in the process of photosynthesis is noted, and the NCPSi values reach 25 g C m\({}^{-2}\). These results are confirmed by direct determinations of phytoplankton parameters [51]. The increase in PP is observed until August.