Spatial and temporal variation in Arctic freshwater chemistry—Reflecting climate‐induced landscape alterations and a changing template for biodiversity

Abstract

1. Freshwater chemistry across the circumpolar region was characterised using a pan-Arctic data set from 1,032 lake and 482 river stations. Temporal trends were estimated for Early (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985), Middle (1986-2000), and Late (2001 periods. Spatial patterns were assessed using data collected since 2001.2. Alkalinity, pH, conductivity, sulfate, chloride, sodium, calcium, and magnesium (major ions) were generally higher in the northern-most Arctic regions than in the Near Arctic (southern-most) region. In particular, spatial patterns in pH, alkalinity, calcium, and magnesium appeared to reflect underlying geology, with more alkaline waters in the High Arctic and Sub Arctic, where sedimentary bedrock dominated.3. Carbon and nutrients displayed latitudinal trends, with lower levels of dissolved organic carbon (DOC), total nitrogen, and (to a lesser extent) total phosphorus (TP) in the High and Low Arctic than at lower latitudes. Significantly higher nutrient levels were observed in systems impacted by permafrost thaw slumps. 4. Bulk temporal trends indicated that TP was higher during the Late period in the High Arctic, whereas it was lower in the Near Arctic. In contrast, DOC and total nitrogen were both lower during the Late period in the High Arctic sites. Major ion concentrations were higher in the Near, Sub, and Low Arctic during the Late period, but the opposite bulk trend was found in the High Arctic.

Biogeochemical responses over 37 years to manipulation of phosphorus concentrations in an Arctic river: The Upper Kuparuk River Experiment

“…In framing the UKRE, we initially anticipated that phosphorus delivery would increase with permafrost thaw (Bowden et al, 2008). In contrast, we observed a strong decrease in DOP flux (Figure 3) and decrease in TDP concentration (Kendrick et al, 2018) over time, consistent with a recent synthesis documenting pan‐Arctic decreases in total P in the Sub and Near Arctic (Huser et al, 2020). It is intriguing to connect decreasing P concentrations to widely documented permafrost thaw (e.g., Biskaborn et al, 2019; Box et al, 2019) and mobilization of iron from previously frozen soils (Herndon et al, 2017; Herndon et al, 2019).…”

“…Over the 37‐year period of seasonal monitoring in the UKRE, we have observed a significant decade‐by‐decade increase in nitrate flux during the fertilization period (Figure 3), consistent with changes in nitrate concentration reported from the Kuparuk River (Frey & McClelland, 2009 and sources therein; Kendrick et al, 2018) and trends in TN concentration observed in some – but not all – Arctic rivers (Huser et al, 2020). Given that discharge has not changed significantly during the period of record (Figure S1), we conclude that the more important driver of change in flux has been a change in concentration.…”

“…Over the 37-year period of seasonal monitoring in the UKRE, we Letters indicate significant differences between reaches within each cover type trends in TN concentration observed in somebut not all -Arctic rivers (Huser et al, 2020). Given that discharge has not changed significantly during the period of record ( Figure S1), we conclude that the more important driver of change in flux has been a change in concentration.…”

Improving the framework for assessment of ecological change in the Arctic: A circumpolar synthesis of freshwater biodiversity

“…Besides temperature and spatial connectivity, water chemistry was also found to be an important diversity correlate, particularly for diatoms. Low diatom diversity in lakes in northern Quebec and Labrador in eastern Canada is likely to be a consequence of the historically stable cold temperatures in that region (Prowse et al, 2006) and the influence of the soft waters of lakes on the Precambrian Shield in this region (Huser et al, 2022;Kahlert et al, 2022).…”

Strontium isotopes reveal diverse life history variations, migration patterns, and habitat use for Broad Whitefish (Coregonus nasus) in Arctic, Alaska

“…The accelerated impacts of climate change at high latitudes [11,12] are a major threat to Arctic freshwater ecosystems [13], altering streamflow [14][15][16][17], warming [18,19] and drying [20] aquatic habitats; causing eutrophication [21] and browning of lakes [22,23]; and allowing for northward range expansion of eurythermic species [24]. To a lesser extent, long-range pollution [7], habitat loss and degradation, and flow modification from oil and gas development [25] can occur independently or interact with climatic change to alter Arctic freshwater ecosystems [26].…”