Nutrient inputs from subarctic rivers into Hudson Bay

Hudson Bay (HB), a large subarctic inland sea, is impacted by rapid climate change and anthropogenic disturbance. HB plays crucial roles in supporting resident migratory species of birds marine mammals, providing subsistence to coastal communities, exporting nutrients into the western Labrador Sea. To better constrain impact river on ecosystem obtain contemporary reference point which future can be evaluated, we estimated fluxes nitrate plus nitrite (N), phosphate (P), silicate using historical nutrient data conjunction with discharge estimates produced three global models. Concentrations molar ratios different exhibited contrasts between sectors HB, attributed diversity geological settings across distinct watersheds. With respect needs primary producers, waters were characterized shortage P during winter spring (N:P dissolved >16), nearly balanced N:P summer, N fall < 16). Southwestern rivers made largest regional contribution total annual delivery all nutrients, followed modest contributions from southern eastern rivers, minor ones northwestern rivers. While regulation flow Nelson La Grande had no discernible concentrations ratios, it clearly shifted transports toward when biological activity estuaries reduced. Finally, potential amount new production supported riverine inputs was two orders magnitude (1.8 × 1011 g C yr−1) lower than (7.3 1012 yr−1). Although small (2.4%) at bay-wide scale, significant locally.