Concentrations of major biogenic elements in the photic layer of the Kandalaksha Bay and production of organic matter

Data on spatial and temporal variability of concentrations and speciations of major nutrients (oxygen, phosphorus, nitrogen, and silicon) in deep waters of the Kandalaksha Bay are presented. Main variations of nutrients in the photic layer associate with seasonal variations in intensity of production and degradation processes. High primary productivity in the spring-summer period results in oxygen oversaturation (103-115%), minimum concentrations of mineral silicon, phosphorus and nitrogen along with increase of their organic forms. Simultaneously under pycnocline concentrations of mineral silicon, phosphorus and nitrogen increase with depth. Distribution of mineral silicon and phosphorus in the deep water layers is under significant influence of waters entering from the Gorlo Straight. In deep water part of the bay nitrogen occurs mainly in organic forms, while phosphorus occurs mainly in mineral forms. An estimation of new primary production on the base of seasonal variations of major nutrient concentrations has been done and great contribution of primary production from recycling of biogenic elements to productivity of these waters has been revealed.