| Summary: | Terminal glaciers of the Greenland Ice Sheet are bordered by hundreds of fjords and other marine areas. At the terminus of a marine-terminating glacier, a large amount of freshwater and suspended sediment (SS) is injected into the fjord by subglacial discharge. The meltwater discharge entrains lower waters and upwells along the glacier front, thereby supplying nutrients to the upper layers of the fjord. This process can increase biological production in the surface layer during the summer melt season. To investigate the influence of subglacial discharge on the net primary production (NPP) in a glacial fjord, a numerical simulation of the Bowdoin Fjord in Greenland was performed by introducing a lower trophic level ecosystem model into a non-hydrostatic ocean model. Sensitivity experiments were also conducted to estimate the effects on NPP due to possible changes in meltwater discharge and glacier recession that may occur as a consequence of climate change. Results of the experiments showed that the NPP increases with a greater amount of glacier meltwater injected from deeper subglacial outlet. The positive influence of the discharge on NPP is not the case in a region where ample SS supplies inhibit photosynthesis. As meltwater discharge increases and the subglacial outlet becomes shallower, NPP is expected to become 1.2 times larger than that at present. However, if warming further progresses to a critical level, NPP declines to as small as 1/8th to 1/9th of the present value.
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