Physical and chemical limnology of 204 lakes from the Canadian Arctic Archipelago (original) (raw)
Related papers
2012
This study examined water chemistry from 113 lakes and ponds across the eastern Canadian Arctic to address the lack of limnological data and understanding of relationships among limnological variables across key local and regional gradients. Environmental and geochemical variables were compared at both the local and regional scale with the use of multivariate analysis. A principal components analysis indicated that there was a primary gradient in temperature, nutrients, and conductivity between sampled regions. In addition, there were significant regional differences observed for nutrients total nitrogen (TN) and total phosphorus (TP), chlorophyll a, and dissolved major ions determined via canonical variates analysis. Across all regions TN:TP ratios were high, indicating phosphorus limitation, and midsummer surface water temperature was strongly correlated to dissolved nitrogen concentrations. Local landscape characteristics were also examined, with multiple samples from lakes of varying elevations, surface area, and depth within the same area. Shallow pond systems (<2 m depth) were found to have significantly higher variability for major ions, especially in areas with influences from local geology. Likewise, the concentration of nutrients and ions in ponds were strongly correlated to concentrations of dissolved organic carbon, likely indicating the influence of watershed inputs and resuspended sediments on the limnology of ponds. Although there was higher regional variation in the limnology of pond systems than lakes, the general patterns within each region were similar.
Limnology of 46 lakes and ponds on Banks Island, N.W.T., Canadian Arctic Archipelago
Hydrobiologia, 2005
The goal of this study was to describe and quantify the physical and chemical limnological properties of 46 lakes and ponds on Banks Island, to explore the effects of ecoclimatic differences on the water chemistry of these study sites, and to establish baseline conditions for this previously unexplored limnological region, which could then be used in subsequent long-term environmental monitoring programs. A key finding was that the study sites on Banks Island represented a large nutrient concentration gradient from ultra-oligotrophic to hypereutrophic waters. In general, the study sites were relatively nutrient rich by Arctic standards (i.e. mean total nitrogen (TN mean)=504.2lg/l and mean total phosphorus (TPU mean)=18.0lg/l); concentrations that are amongst the highest of any previous limnological survey from similar latitudes. Dissolved organic carbon (DOC) concentrations were also some of the highest reported to date amongst all other Canadian Arctic island limnological surveys. These values reflect the milder climate, concentrated animal life and lushness of Banks Island, as compared to other Canadian Arctic Archipelago islands. Principal components analysis (PCA) separated sites along a conductivity/ionic and elevation gradient on Axis 1 (k 1 =0.343), and a metal (Fe, Zn, Al) and alkalinity-related (DIC, pH) gradient on the second axis (k 2 =0.187). Canonical variate analysis (CVA) was used to explore the classification of the study sites into Low Arctic, Mid Arctic or High Arctic designations based on their limnological characteristics.
Fundamental and Applied Limnology / Archiv für Hydrobiologie, 2007
The limnological features that characterize the shallow ponds (<2 m deep) and lakes (> 2 m deep) on Bathurst Island, Nunavut, Canada were examined through chemical analyses and multivariate statistical methods as part of a larger ongoing survey to document and monitor environmental changes in these remote and sensitive areas. All sites were relatively oligotrophic and alkaline. Nutrient ratios indicated that nitrogen could be limiting algal growth to a greater degree than phosphorus in over 63 % of the sites. Principal components analysis (PCA) was used to explore the patterns of variation in the limnological dataset. The three dominant limnological gradients were: major ion content and dissolved organic carbon (DOC) levels along Axis 1; and pH along Axis 2.
Evidence of eutrophication in Arctic lakes
Arctic Science
Lakes and ponds are dominant components of Arctic landscapes and provide food and water for northern communities. In the Greiner Lake watershed, in Cambridge Bay (Nunavut, Canada), water bodies are small (84% <5 ha) and shallow (99% <4 m deep). Such characteristics make them vulnerable to eutrophication as temperatures rise and nutrient concentrations from the greening landscape increase. Here, we investigated and compared 35 lakes and ponds in the Greiner watershed in August 2018 and 2019 to determine their current trophic states based on their chemical composition and phytoplankton communities. The ponds had higher trophic status than the lakes, but overall, most sites were oligotrophic. Lake ERA5, located upstream of any direct human influence was classified as eutrophic due to high total phosphorus (32.3 μg·L−1) and a high proportion of Cyanobacteria (42.9% of total phytoplankton biovolume). Satellite imagery suggests the lake may have been eutrophic for the last 30 years....
Aquatic Sciences, 2006
We compared physicochemical properties and rates of phytoplankton and epipelic primary production in two shallow lakes in the Alaskan arctic on eight occasions over three years. The two morphometrically similar lakes lacked defined inlets and had a mean depth of 2.2 m. The lakes differed with respect to glacial influence. Lake GTH 112 was continuously turbid due to resuspension of glacial silt from the lake bed, while GTH 114 showed higher clarity as it was situated on coarser glacial drift. The two lakes contrasted sharply in euphotic zone nutrient concentrations. Soluble reactive phosphorus, NO3--N and NH4+-N concentrations averaged 0.17, 2.5 and 12.6 μM, respectively, in GTH 112, but were generally at or below the detection limit of 0.05 μM in GTH 114. Reduced light limited the ability of phytoplankton in GTH 112 to use the increased nutrients, and volume-based rates of phytoplankton primary production were similar between lakes. High turbidity in GTH 112 decreased the average percentage of total lake volume and sediment surface within the euphotic zone to 63% and 47%, respectively, compared with values of 88% and 85%, respectively, for GTH 114. Consequently, the average whole lake (phytoplankton plus epipelic) primary production rate in GTH 112 (8.5 mmol m-2 d-1) was significantly lower than the mean rate (12.3 mmol m-2 d-1) for GTH 114. The increase in turbidity affected benthic and pelagic habitats proportionately, as epipelon accounted for about 25% of total whole lake primary production in both lakes.
Climatically controlled chemical and biological development in Arctic lakes
Journal of Geophysical Research: Biogeosciences, 2007
We investigated the factors controlling lake evolution in Arctic ecosystems using a multiproxy paleolimnological approach on a small lake on Baffin Island, Arctic Canada. Lakewater pH was inferred from fossil diatom assemblages, whereas primary production was assessed from sediment concentrations of diatom valves and spectrally inferred chlorophyll a. Our reconstructed limnological variables registered synchronous changes and showed a close coupling to Holocene climatic fluctuations, as inferred by numerous independent paleoclimate proxies. Without exception, our highest pH and production values occurred during warm intervals, and vice-versa. A return towards paleolimnological conditions of the warm early Holocene has occurred since the midtwentieth century, corresponding to climate warming following the Little Ice Age. Maximum recent values of our reconstructed parameters are either directly comparable to, or in some cases exceed, values attained during the Holocene Thermal Maximum, 8000-10,000 years ago. Our data suggest that climate has a first-order influence on primary production and the regulation of in-lake DIC dynamics (and hence on lakewater pH) through its modulation of lake ice cover. We conclude that direct forcing by climate is more important than catchment processes in controlling the chemical and biological development of ice-dominated Arctic lake ecosystems, at the scale of the Holocene.
Climate-related drivers of nutrient inputs and food web structure in shallow Arctic lake ecosystems
2022
In order to predict the effects of climate change on polar ecosystems, disentangling mechanisms of nutrient transfer in food webs is crucial. We investigated sources of nutrients in tundra lakes, tracing their transfer through the food web and relating the observed patterns to runoff, snow coverage, and the presence of migratory geese in lake catchments. C and N content (elemental and isotopic) of several food web components including Lepidurus arcticus (Notostraca, at the top of the lake food webs) in 18 shallow Arctic lakes was compared. Terrestrial productivity and geese abundance were key biotic factors that interacted with abiotic variables (snow coverage, lake and catchment size) in determining the amount and origin of nutrient inputs, affecting the trophic interactions among aquatic species, food chain length and nutrient flow in Arctic lake food webs. Decreasing snow coverage, increasing abundance and expansion of the geese's range are expected across the Arctic due to climate warming. By relating nutrient inputs and food web structure to snow coverage, vegetation and geese, this study contributes to our mechanistic understanding of the cascade effects of climate change in tundra ecosystems, and may help predict the response of lakes to changes in nutrient inputs at lower latitudes. Global climate change is expected to affect nutrient cycling and transfer in food webs via physically and biologically mediated mechanisms 1-3. Such changes will be particularly marked in the Arctic, due to the Arctic warming amplification 4-7 and nutrient-limited conditions 8,9. Admittedly, although abiotic changes are evidently transforming the region, our ability to predict their ecological effects is limited 10-12. Shallow Arctic lake ecosystems represent hotspots of biodiversity and productivity 6,13 and provide ecosystem services both at the local and the global scale (e.g. they are important carbon sinks) 14,15. Although they occupy less than 2% of the tundra, numerous aquatic and terrestrial species depend on these systems. Expected warming and greater precipitation will affect seasonal snow coverage, primary productivity, runoff in catchment areas and the density of migratory geese 16-19 , all of which represent important drivers of nutrient input and exchange between terrestrial and aquatic compartments 20,21. Nevertheless, local-scale differences in these factors, as well as in lake and catchment area size, make it difficult to make general predictions about the effect of climate change on nutrient cycling and Arctic food webs. A complete understanding of nutrient cycling in Arctic lake ecosystems should take account of food webmediated effects on productivity and remineralisation processes 6,13,22,23. Indeed, grazing by geese may affect vegetation biomass and the amount of nutrients stored in soil 24-28 , while top-down control by aquatic invertebrates may limit summer algal blooms even when high nutrient inputs are available 29. In addition, consumers' trophic niches are affected by resource availability and play an important role in nutrient transfer and food web structure 30-34. Thus, they have the potential to modulate the effects of climate change and other stressors on ecosystems 22,35. In this context, C and N isotopic and elemental analyses represent powerful tools with which to quantify the relative importance of distinct sources of nutrients in sediments and soil, taken up by vegetation and transferred along food chains 36-39. The isotopic signature of nitrogen (15 N/ 14 N, or δ 15 N, reported as per mil difference with
Epipelic and pelagic primary production in Alaskan Arctic lakes of varying depth
Hydrobiologia, 2008
We compared on eight dates during the ice-free period physicochemical properties and rates of phytoplankton and epipelic primary production in six arctic lakes dominated by soft bottom substrate. Lakes were classified as shallow (z ̅ < 2.5 m), intermediate in depth (2.5 m < z ̅ < 4.5 m), and deep (z ̅ > 4.5 m), with each depth category represented by two lakes. Although shallow lakes circulated freely and intermediate and deep lakes stratified thermally for the entire summer, dissolved oxygen concentrations were always >70% of saturation values. Soluble reactive phosphorus and dissolved inorganic nitrogen (DIN = NO3—N + NH4+–N) were consistently below the detection limit (0.05 μmol l-1) in five lakes. However, one lake shallow lake (GTH 99) periodically showed elevated values of DIN (17 μmol l-1), total-P (0.29 μmol l-1), and total-N (33 μmol l-1), suggesting wind-generated sediment resuspension. Due to increased nutrient availability or entrainment of microphytobenthos, GTH 99 showed the highest average volume-based values of phytoplankton chlorophyll a (chl a) and primary production, which for the six lakes ranged from 1.0 to 2.9 μg l-1 and 0.7-3.8 μmol C l-1 day-1. Overall, however, increased z ̅ resulted in increased area-based values of phytoplankton chl a and primary production, with mean values for the three lake classes ranging from 3.6 to 6.1 mg chl a m-2 and 3.2-5.8 mmol C m-2 day-1. Average values of epipelic chl a ranged from 131 to 549 mg m-2 for the three depth classes, but levels were not significantly different due to high spatial variability. However, average epipelic primary production was significantly higher in shallow lakes (12.2 mmol C m-2 day-1) than in intermediate and deep lakes (3.4 and 2.4 mmol C m-2 day-1). Total primary production (6.7-15.4 mmol C m-2 day-1) and percent contribution of the epipelon (31-66%) were inversely related to mean depth, such that values for both variables were significantly higher in shallow lakes than in intermediate or deep lakes.