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Abstract Tidewater glaciers in Kongsfjorden, Svalbard, are retreating, and it is expected that they will terminate on land at some time in the future. Plumes, the submerged runoff emerging at the bases of tidewater glacier fronts, contribute to large-scale circulation within the inner fjord. A transition to a fjord with only land-terminating glaciers will affect the fjord circulation, with further implications for the biogeochemistry and ecosystem in Kongsfjorden. In this paper we compare the present and predicted future circulation using the ocean model system ROMS, and identify and quantify changes resulting from the altered forcing. Removal of subglacial discharge due to retreating tidewater glaciers causes substantial reduction of subsurface volume fluxes, and hence exchange rates, in the inner part of the fjord, and results in enhanced stratification during summer months. The increase in fjord extent due to tidewater glacier retreat results in a slight increase in tidal velocities, in particular overtide components, but this effect is not strong enough to compensate for the reduction in current velocities due to removal of freshwater plumes at glacier fronts. The freshwater content (practical salinity < 34.8) in the fjord during the melting season is predicted to increase in the future, primarily due to enhanced retention of freshwater in the inner parts of the fjord. However, freshwater in the future will mostly be confined to a relatively thin surface layer whereas at present freshwater is found in a thicker layer, in particular in the proximity of the tidewater glacier fronts. [ABSTRACT FROM AUTHOR]

This study is the third in a series of papers on the Chupa Estuary, White Sea, Russia, and investigates tidal and seasonal fate and fluxes of materials from a small fjord-like Arctic estuary to the coastal zone. Respective companion papers have detailed the hydrography (Estuar. Coast. Shelf Sci. 48 (1999) 1) and metals in sediments and mussels (Estuar. Coast. Shelf Sci. 48 (1999) 13). Two seasonal cruises were undertaken in summer (July 1994) and autumn (September, 1995). Nutrients (nitrate, nitrite, phosphate and silicate) and dissolved oxygen were recorded along the estuarine longitudinal axis and at diurnal anchor stations at key points in the estuary. The fluvial nutrient input was negligible throughout. Nutrient concentrations showed considerable inter-tidal and spring–neap variability. Evidence from isopycnals showed that this variability is related to water exchange processes in the deep basins where renewal takes place within the space of a tidal cycle. Deep-water renewal and cascading is more pronounced on neap tides due to reduced turbulent mixing. The downwelling of seawater ensures that the deep basin waters are well ventilated, and provides a means of coupling between bottom and surface water nutrient pools whereby remineralized nutrients are dispersed and recirculated. Nutrient fluxes to the coastal zone were quantified in autumn as a net import of dissolved inorganic silicate (DSi) and dissolved inorganic phosphate (DIP) at 2.10 and 0.51 mol s−1, respectively, and a dissolved inorganic nitrate + nitrite (DIN) export of 1.72 mol s−1. In July DIN, DIP and DSi were exported at 3.57, 0.41 and 7.04 mol s−1, respectively. An assessment of hydrodynamical parameters shows that the circulation is complex throughout the estuary, and so the resolved fluxes are semi-quantitative. Fjord-like circulation results in a large export of inorganic nutrients in the lower nutrient-rich layers compared to the incoming intermediate layers, which drives the system towards N-limitation in both summer and autumn, thus lending support to the concept of N-limiting tendencies observed in other sub-Arctic areas. [Copyright &y& Elsevier]

Abstract: The paper examines the meio- and macrobenthic responses to physical disturbance and sediment instabilities in a small Arctic glacier-fed river estuary. Zajiczkowski and Włodarska-Kowalczuk [Zajiczkowski, M., Włodarska-Kowalczuk, M., 2007. Dynamic sedimentary environments of Arctic glacier-fed river estuary (Adventfjorden, Svalbard). I. Flux, deposition, and sediment dynamics. Estuarine, Coastal and Shelf Science 74(1–2), 285–296] distinguished three zones in Adventfjorden (west Spitsbergen) estuary: the tidal flat, the slope (high sedimentation, frequent sediment slides), the central basin (low sedimentation, stable sediments). The numbers of individuals and species of meio- and macrofauna were very low on the tidal flat. The total densities of meio- and macrofauna were significantly lower on the slope of the glacio-fluvial delta than in the central basin. Only the macrofauna responded to sediment instabilities on the slope by a significant decrease in total biomass. Nematodes inhabiting the slope sediments were larger than those in the central basin, although there was no significant difference in the size of harpacticoids in the two zones. The frequently disturbed, resuspended, and redeposited slope sediments were colonized by the opportunistic polychaete Capitella capitata agg. and by the high sedimentation resistant polychaetes Chaetozone setosa agg. and Cossura longocirrata. Tube-dwelling, sedentary, or suspension-feeding fauna only occurred at the central basin stations. The species richness and ratio of surface-dwelling to burrowing deposit-feeders in the macrobenthic communities decreased towards the river mouths. The differences in the taxonomic composition of communities inhabiting the sediments of the slope and the central basin were less pronounced in meiofauna (studied at a higher taxonomic level) than in the macrofauna (identified to the species level). Nevertheless, the differences were significant for both benthic compartments (ANOSIM test, P <0.05). The simultaneous survey of meio- and macrobenthic communities in an Arctic glacier-fed river estuary shows that both benthic compartments are sensitive to sediment instabilities and physical disturbance caused by high sedimentation and frequent sediment gravity flows. [Copyright &y& Elsevier]