Subarctic Lake Research Articles

Role of terrestrial carbon in aquatic UV exposure and photoprotective pigmentation of meiofauna in subarctic lakes

Summary Aquatic organisms are adversely influenced by ultraviolet radiation (UV) and utilise photoprotective strategies, including pigmentation. We examined UV‐protective melanin pigmentation of aquatic meiofauna (Cladocera) in relation to the UV exposure across 25 tree line lakes in Finland to address the potential effects of increased UV and altered input of UV‐screening terrestrial dissolved organic carbon (DOC) on aquatic organisms. Bio‐optical parameters, including concentration of DOC, the coloured dissolved organic matter (CDOM) fraction, a suite of carbon quality indices and chlorophyll a, were analysed from lake water, and their role in controlling underwater UV environment (measured as diffuse UV attenuation coefficient Kd at 305 and 340 nm) was examined. Cladoceran (Alona affinis) carapaces were extracted from the surface sediments, and their melanisation was assessed with spectroscopic UV‐visible light absorbance measurements. DOC, CDOM and specific UV absorbance (SUVA) had strong positive relationships with the attenuation of UV in the lakes, suggesting that terrestrial organic carbon controls underwater UV exposure in the examined lakes. The absorbance measurements indicated the presence of melanin in the cladoceran carapaces, the degree of melanisation varying strongly among the lakes. Melanisation had significant relationships with SUVA and fluorescence index (FI). It was higher in lakes with low SUVA and high FI, indicating that cladocerans exhibit strong melanisation in lakes with low contribution of UV‐attenuating allochthonous DOC (i.e. high UV exposure). The results suggest that cladoceran meiofauna respond to UV by utilising photoprotective pigmentation and that the degree of pigmentation is affected by site‐specific underwater UV exposure, which is ultimately controlled by UV‐attenuating DOC of terrestrial origin. Although cladoceran meiobenthos are able to adapt to varying underwater UV doses, climate change with its multiple consequences on hydrology, limnology and catchment vegetation in the tree line zone may cause major changes in underwater UV environment for the organisms to adapt.

Microbes track pollution through time

Mercury Microbiology Genes present in buried lake sediments can help reconstruct how microbial ecosystems responded to past exposure to mercury. When atmospheric mercury transported around the globe is eventually deposited in terrestrial or aquatic environments, microorganisms control its cycling and bioaccumulation. Poulain et al. isolated ancient microbial DNA from sediments in remote subarctic lakes in the Hudson Bay Lowlands of Canada. The distribution of genes coding for mercuric reductase (merA), the primary enzyme involved in mercury detoxification, correlates with historical mercury deposition, including a rapid population shift at the onset of the Industrial Revolution. ISME J. 10.1038/ismej.2015.86 (2015).

Community- and population-level changes in diatom size structure in a subarctic lake over the last two centuries.

Climate change over the last two centuries has been associated with significant shifts in diatom community structure in lakes from the high arctic to temperate latitudes. To test the hypotheses that recent climate warming selects for species of smaller size within communities and a decrease in the average size of species within populations, we quantified the size of individual diatom valves from 10 depths in a sediment core covering the last ∼200 years from a pristine subarctic lake. Over the last ∼200 years, changes in the relative abundance of species of different average size and changes in the average valve size of populations of species contribute equally to the changes in community size structure, but are often opposite in sign, compensating for one another and moderating temporal changes in community size structure. In the surface sediments that correspond to the recent decades when air temperatures have warmed, the mean size of valves in the diatom community has significantly decreased due to an increase in the proportion of smaller-sized planktonic diatom species.

Source water inputs and catchment characteristics regulate limnological conditions of shallow subarctic lakes (Old Crow Flats, Yukon, Canada)

Climate variations exert rapid and strong control on the hydrology of shallow lake-rich subarctic landscapes, but knowledge of the associated effects on limnological conditions remains limited. Based on analysis of water isotope compositions and water chemistry at 56 lakes across Old Crow Flats (Yukon), a large thermokarst landscape, we assess if differences in source water inputs (snowmelt versus rainfall) affect limnological conditions during the ice-free season of 2007 and explore influences of catchment features. Results demonstrate that lakes with snowmelt-dominated source waters, situated in catchments that support tall shrub and woodland vegetation, possess significantly higher (p < 0.05) nutrient (N, P, SiO2) and dissolved organic carbon concentrations than lakes with rainfall-dominated source waters. Conversely, rainfall-dominated lakes, located in catchments dominated by dwarf shrubs and sparse vegetation, have significantly higher concentrations of major ions (Mg2+, Na+, SO42−) and pH. These limnological differences persisted throughout the ice-free season. We suggest that interaction of snowmelt with organic-rich detritus raises nutrient concentrations in snowmelt-dominated lakes and that evaporative-concentration, shoreline erosion and possibly rainfall runoff are processes that raise the ionic content of lakes with rainfall-dominated source waters. Knowledge of these relations improves the ability to anticipate limnological responses to ongoing and future climate and hydrological change in Arctic and subarctic regions.

Food consumption rates of piscivorous brown trout (Salmo trutta) foraging on contrasting coregonid prey

AbstractKnowledge of predator–prey dynamics is essential to understand ecosystem functioning. Quantification of such interactions is important for fisheries management, in particular in the case of stocking programmes. Here, food consumption rates (FCR) were quantified for wild and stocked piscivorous brown trout, Salmo trutta L., in three subarctic lakes with contrasting coregonid (Coregonus spp.) prey communities, using the Wisconsin and the Elliott–Hurley bioenergetic models. FCR was highest for stocked brown trout in lakes with the lowest predator densities, and lowest for wild brown trout. Although FCR estimate may vary somewhat depending on the specific model used, such tools are imperative for the proper impact assessment of brown trout stocking programmes and for the provision of advice on optimal stocking densities.

Resource partitioning among top-level piscivores in a sub-Arctic lake during thermal stratification

Abstract In systems with multiple piscivores, co-occurrence is dependent on resource partitioning. This is pronounced in oligotrophic northern lakes, which have simple food webs and short open-water seasons. We used acoustic telemetry and stable isotopes to quantify habitat and dietary partitioning during thermal stratification among three piscivores that commonly co-occur in Canadian sub-Arctic lakes—burbot (Lota lota), lake trout (Salvelinus namaycush), and northern pike (Esox lucius). Spatial core areas and core habitat niches (space and depth) did not significantly overlap among species. Although burbot and lake trout occupied similar mean daily depths (16.2 m and 13.4 m, respectively), and water temperatures (5.4 °C and 6.9 °C, respectively), they were spatially segregated. Burbot were closely associated with the lake bottom on steep drop-offs between the offshore and nearshore zone with moderate substrate complexity, whereas lake trout were located over deep offshore basins and suspended above the lake bottom. Northern pike occupied shallow depths (5.3 m) and warmer water (16.5 °C) within the nearshore region and were closely associated with bottom substrate of highest complexity. Some significant overlap among spatial home ranges and broad habitat niches indicated that these species interact. However, dietary niches did not significantly overlap at either the core or broad levels, suggesting that species were utilizing spatially diverse food sources. Our results highlight the importance of including depth and space when quantifying resource partitioning among fishes and provide insight into the mechanisms that promote piscivore co-occurrence in northern lakes.

Predicting Total Nitrogen, Total Phosphorus, Total Organic Carbon, Dissolved Oxygen and Iron in Deep Waters of Swedish Lakes

In many lakes, the physical and chemical characteristics are monitored for surface waters but not for deep waters. Yet, deep waters may be important for understanding the dynamics of lake water chemistry variables over the year. In this study, multiple regression models have been created for five different variables, total phosphorus, total nitrogen, total organic carbon, dissolved oxygen (DO) and iron, in the deep water for 61 Swedish temperate or subarctic lakes. The investigated season was February to October, depending on the data availability. Regressions used the corresponding variables from the surface water as well as different morphometric parameters as independent variables. It was possible to construct meaningful models (r 2 > 0.65; p < 0.05) for most of the variables and months. However, it was not possible to attain this criterion for some months regarding the DO concentration. Surface water concentrations were in general most important for predicting corresponding deep water concentrations. An exception was that during summer, DO differed considerably between surface waters and deep waters and voluminous lakes had particularly high DO concentrations in deep waters. No cross-systems relationship could be found between deepwater hypoxia and total phosphorus in deep waters during summer when phosphorus diffusion from sediments is most likely. A mass-balance modelling example was applied to illustrate the use of the produced models. These findings may provide a better understanding of the dynamics of these five variables in temperate or subarctic lakes.

Diel bank migration of Burbot (Lota lota)

Determining the habitat use and movements by fish is critical to our understanding of aquatic ecosystem function. The objective of this study was to assess the diel movements of Burbot (Lota lota) over the open water season. We employed a high-resolution acoustic telemetry positioning system to track the movements and activity of four Burbot during the ice-free season (between June and September) in a sub-Arctic lake. Burbot underwent diel bank migration (DBM), a benthic form of diel vertical migration, where depths are transitioned in close association with the bottom rather than through the water column. During daytime, Burbot occupied deeper water, at the transition of soft, low complexity substrates and ascended along the rocky bottom lake banks to shallower water habitats at night. Increased activity rates during shallow water forays suggest active feeding events. DBM was low at the start of summer with nearly 24 h of daylight, but increased towards the mid-summer with a more pronounced night cycle, coalescing towards the fall. The DBM of Burbot is dynamic, with proximate triggers of light and temperature, and ultimate causes likely being foraging opportunities, bioenergetics gain and predator avoidance.

Evidence for Mass-Independent Fractionation of Mercury Isotopes by Microbial Activities Linked to Geographically and Temporally Varying Climatic Conditions in Arctic and Subarctic Lakes

Cores from Arctic and subarctic Canadian lakes were subjected to isotopic, chemical, micropaleontological, and geochronological analyses for the purpose of investigating mass-independent fractionation (MIF) of mercury isotopes. The cores preserved records of early twentieth century climatic warming (∼1915–1940), subsequent cooling (∼1940–1970), and renewed warming (∼1970–2004) [phases W1, C1, and W2, respectively]. Per mil deviations of 199Hg/202Hg and 201Hg/202Hg ratios due to MIF (Δ199Hg and Δ201Hg values) correlated with biological and biogeochemical factors linked to geographical and temporal climatic variations but varied, in large part, independently of each other. Δ201Hg tended to increase from east to west. Among subarctic lakes this trend paralleled westward decreases in annual precipitation, diatom concentration, and the post-1990 organic carbon/pre-1900 organic carbon ratio, and Δ201Hg increased in the order C1 ≤ W1 < W2. Δ201Hg varied inversely with diatom concentration, but Δ199Hg increased with increasing abundance of cyanobacteria. Arctic lakes, however, showed a south-to-north decrease in Δ199Hg/Δ201Hg ratios, paralleling a decrease in annual precipitation and an increase in Chlorophyta and cyanobacteria. Δ-values of individual lakes depended on the abundances of specific phylogenetic groups of phytoplankton, pyrolysis products of organic matter, and manganese, and on the manganese/iron ratios of oxyhydroxides, displaying clear separation of data representing different climatic trends. These results suggest that MIF was caused by microorganisms, such as bacteria which decomposed dead phytoplankton and mediated oxidation-reduction reactions of manganese and iron, and that the nature and isotope-fractionating activities of the microflora varied with climate-related environmental and biotic factors, including the community structure of the phytoplankton.

Climate‐forced changes in available energy and methane bubbling from subarctic lakes

AbstractStrong correlations between seasonal energy input and methane (CH4) bubbling (ebullition) in northern lakes suggest that energy proxies might provide a constraint on the magnitude of future CH4 emissions. Ebullition is a major pathway for transporting anaerobically produced CH4 from lake sediments to the atmosphere and represents a large unquantified CH4 source. In high‐latitude, postglacial lakes during the ice‐free season, solar shortwave energy input can constrain CH4 productivity via control of sediment temperature. Utilizing long‐term climatic predictors, we calculate CH4 ebullition from three subarctic lakes in northern Sweden over the period of 1916–2079. Using observed energy trends, the seasonal average lake CH4 ebullition is predicted to increase by 80% between the 1916–1926 decade and the 2040–2079 period. Present‐day seasonal average methane ebullition is estimated to have already increased 24% since the 1916–1926 decade.

Lake size and fish diversity determine resource use and trophic position of a top predator in high-latitude lakes.

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes covering a marked gradient in size (0.5–1084 km2) and fish species richness (2–13 species). We expected top predators to shift from littoral to pelagic energy sources with increasing lake size, as the availability of pelagic prey resources and the competition for littoral prey are both likely to be higher in large lakes with multispecies fish communities. We also expected top predators to occupy a higher trophic position in lakes with greater fish species richness due to potential substitution of intermediate consumers (prey fish) and increased piscivory by top predators. Based on stable carbon and nitrogen isotope analyses, the mean reliance of Arctic charr on littoral energy sources showed a significant negative relationship with lake surface area, whereas the mean trophic position of Arctic charr, reflecting the lake food-chain length, increased with fish species richness. These results were supported by stomach contents data demonstrating a shift of Arctic charr from an invertebrate-dominated diet to piscivory on pelagic fish. Our study highlights that, because they determine the main energy source (littoral vs. pelagic) and the trophic position of generalist top predators, ecosystem size and fish diversity are particularly important factors influencing function and structure of food webs in high-latitude lakes.

Seasonal depletion of resources intensifies trophic interactions in subarctic freshwater fish communities

Summary Climate change in recent decades has resulted in an increase in both the density and diversity of consumers in subarctic freshwater ecosystems. Despite this, harsh winter conditions in the region limit productivity and may serve as a bottleneck driving trophic interactions within the fish community, potentially determining the outcome of climate change for resident biota. However, due to the difficulties in sampling during winter months, few studies have assessed seasonal variation in the ecological interactions between native and range‐expanding species in subarctic regions. We examined seasonal variation in activity, diet (stomach content) and resource use (δ13C and δ15N stable isotope ratios) of two fishes: the resident cold‐water‐adapted European whitefish (Coregonus lavaretus L.) and the range‐expanding cool‐water‐adapted ruffe (Gymnocephalus cernua L.) in lakes with low and high consumer density. Results were contrasted with seasonal availability of benthic and pelagic resources and indirect measures of individual fitness, that is condition, growth and estimated lipid content (muscle elemental C : N ratio) of both species. The effects of fish density were apparent in both the diet and resource use of whitefish, which altered their diet and displayed reduced stomach fullness during winter in high‐density lakes. This was associated with an overall reduction in whitefish growth, condition and estimated lipid content in high‐density lakes, which was especially pronounced during winter. Ruffe utilised a greater proportion of profundal resources than whitefish in both summer and winter, potentially exploiting a vacant niche. Ruffe maintained condition and lipid reserves throughout the winter, highlighting the potential for further northward range expansion of the species. Winter acts as a seasonal bottleneck in subarctic lakes, but assumptions that this bottleneck primarily selects against warmer‐water‐adapted invasive species such as ruffe may be too restrictive. The effects of seasonal resource depletion on fish condition and invertebrate density were most severe in lakes with a high density of fish, and in these conditions, the cold‐water‐adapted resident whitefish was most adversely affected.

Long-Term Changes in the Water Chemistry of Arctic Lakes as a Response to Reduction of Air Pollution: Case Study in the Kola, Russia

Sixty years of air pollution from two Cu-Ni smelting plants (“Pechenganikel” and “Severonikel”) in the Kola region in northwest Russia have posed a severe threat for water quality, specifically acidification, in subarctic lakes. In the last two decades, emissions of SO2, Cu and Ni from the smelters have declined with 33 %, 40 % and 36 %, respectively. The 75 lakes in Kola Peninsula were sampled with 5-year intervals for the period 1990 to 2010. In addition, were analysed for major anions and cations, DOC and heavy metals. The lakes were grouped according to geology and distance to emission sources into 6 subregions. The most acid-sensitive lakes are located on granites, quartz sands or in highlands. Since 1990, ANС has increased, which is connected to the reduction of the contents strong acids in water (sulphate, chloride) while base cations concentrations have been almost unchanged. Despite the reduction of sulphate, concentrations of alkalinity have not increased in lake water. We have found an increase in concentration of dissolved organic carbon (DOC) and nutrients in Kola lake waters over a 20-year period. We suggest this phenomenon can be explained by two mechanisms: a reduction in deposition of strong acids and warming climate. Concentrations of Ni and Cu have decreased 5-10-fold over the last 20 years. We conclude that reduced emissions from Cu-Ni smelting plants has led to improved water quality in the Kola region.

Environmental features of small subarctic glacial lakes (Khibiny massif, Kola penninsula)

Two subarctic alpine glacial lakes, located at 759 and 812 m above sea level in the Khibiny massif, were investigated. An assessment of the current state of the catchment areas, depth and bottom topography, chemical composition of water and sediments, along with a set of hydrobiological studies of ecosystem components (phyto- and zooplankton, chlorophyll content, benthos, phytoperiphyton) has been made. No serious effects of environmental pollution have been detected in the lakes. The typical ecosystem features include oligotrophic status, low salinity and high oxygen content. The information obtained could be successfully used for regulating anthropogenic load and assessing polluted water bodies of the Kola Subarctic.

Sediment accumulation rates in subarctic lakes: Insights into age-depth modeling from 22 dated lake records from the Northwest Territories, Canada

Age-depth modeling using Bayesian statistics requires well-informed prior information about the behavior of sediment accumulation. Here we present average sediment accumulation rates (represented as deposition times, DT, in yr/cm) for lakes in an Arctic setting, and we examine the variability across space (intra- and inter-lake) and time (late Holocene). The dataset includes over 100 radiocarbon dates, primarily on bulk sediment, from 22 sediment cores obtained from 18 lakes spanning the boreal to tundra ecotone gradients in subarctic Canada. There are four to twenty-five radiocarbon dates per core, depending on the length and character of the sediment records. Deposition times were calculated at 100-year intervals from age-depth models constructed using the ‘classical’ age-depth modeling software Clam. Lakes in boreal settings have the most rapid accumulation (mean DT 20 ± 10 yr/cm), whereas lakes in tundra settings accumulate at moderate (mean DT 70 ± 10 yr/cm) to very slow rates, (>100 yr/cm). Many of the age-depth models demonstrate fluctuations in accumulation that coincide with lake evolution and post-glacial climate change. Ten of our sediment cores yielded sediments as old as c. 9000 cal BP (BP = years before AD 1950). From between c. 9000 cal BP and c. 6000 cal BP, sediment accumulation was relatively rapid (DT of 20–60 yr/cm). Accumulation slowed between c. 5500 and c. 4000 cal BP as vegetation expanded northward in response to warming. A short period of rapid accumulation occurred near 1200 cal BP at three lakes. Our research will help inform priors in Bayesian age modeling.

Divergent growth patterns between juveniles of two sympatric Arctic charr morphs with contrasting depth gradient niche preferences

Seasonal growth patterns have been investigated in juveniles of two reproductively isolated Arctic charr [Salvelinus alpinus (L.)] morphs, which coexist in distinct ecological niches (upper-water and deep-water environments) in a subarctic lake. Offspring (F1-generation) of each of the littoral spawning charr (LO) and the profundal spawning charr (PB) were reared individually over a period of 12 months under simulated natural photoperiod (at 69°N) and two different temperature regimes to mimic the profundal zone conditions with constantly low temperature (~4 °C) and the littoral zone conditions with seasonally cycling temperatures. All charr increased in weight during the experimental period. The LO-morph performed generally best at naturally fluctuating temperature, whereas the PB-morph grew best at a constantly low temperature (4 °C). The LO-morph showed a typical seasonal growth pattern found earlier for anadromous Arctic charr, with elevated specific growth rates (SGR) during June–October and profoundly reduced or negative SGR-values during November–February suggesting that the fish ceased feeding during this period. In contrast, the PB-morph maintained a steady growth rate, regardless of temperature regime, and showed less signs of reduced appetite during the polar night period and exhibited significantly higher SGR-values during late autumn and early winter compared to the LO-morph. This study suggests different heritable adaptations in somatic growth trajectories where the deep-water PB-morph do not show a down-regulation of appetite and voluntary fasting during winter conditions with typically low light intensity and low temperatures, and up-regulation of appetite with hyperphagia during summer, as characteristically found for the upper-water LO-morph and anadromous Arctic charr.

Trophic dynamics of several fish species in lakes of a climatically sensitive region, the Hudson Bay Lowlands

Freshwater lakes in the Hudson Bay Lowlands (HBL) area of Ontario are expected to undergo considerable physical, chemical and biological changes related to climatic change; however, the nature of those changes is still very uncertain. As a first step to improve our understanding of fish communities within these subarctic lakes, we aimed to: (a) characterize trophic dynamics of several large-bodied species within three HBL lakes and (b) determine whether trophic dynamics of selected species in the HBL lakes differed from the same species in Southern Ontario lakes. We found that species-specific trophic position and littoral resource reliance varied significantly within and among the HBL lakes of differing biological communities, chemistry and morphometry. Although several significant differences were evident among lakes in the northern and southern regions, we did not find striking consistent differences in trophic dynamics. Based on observations of high variation in trophic position and/or littoral reliance, we can hypothesize that changes in food resources resulting from climatic change would have little impact on most of the large-bodied species.

Adaptive radiation along a thermal gradient: preliminary results of habitat use and respiration rate divergence among whitefish morphs.

Adaptive radiation is considered an important mechanism for the development of new species, but very little is known about the role of thermal adaptation during this process. Such adaptation should be especially important in poikilothermic animals that are often subjected to pronounced seasonal temperature variation that directly affects metabolic function. We conducted a preliminary study of individual lifetime thermal habitat use and respiration rates of four whitefish (Coregonus lavaretus (L.)) morphs (two pelagic, one littoral and one profundal) using stable carbon and oxygen isotope values of otolith carbonate. These morphs, two of which utilized pelagic habitats, one littoral and one profundal recently diverged via adaptive radiation to exploit different major niches in a deep and thermally stratified subarctic lake. We found evidence that the morphs used different thermal niches. The profundal morph had the most distinct thermal niche and consistently occupied the coldest thermal habitat of the lake, whereas differences were less pronounced among the shallow water pelagic and littoral morphs. Our results indicated ontogenetic shifts in thermal niches: juveniles of all whitefish morphs inhabited warmer ambient temperatures than adults. According to sampling of the otolith nucleus, hatching temperatures were higher for benthic compared to pelagic morphs. Estimated respiration rate was the lowest for benthivorous profundal morph, contrasting with the higher values estimated for the other morphs that inhabited shallower and warmer water. These preliminary results suggest that physiological adaptation to different thermal habitats shown by the sympatric morphs may play a significant role in maintaining or strengthening niche segregation and divergence in life-history traits, potentially contributing to reproductive isolation and incipient speciation.

Pronounced chemical response of Subarctic lakes to climate-driven losses in surface area.

Losses in lake area have been observed for several Arctic and Subarctic regions in recent decades, with unknown consequences for lake ecosystems. These reductions are primarily attributed to two climate-sensitive mechanisms, both of which may also cause changes in water chemistry: (i) increased imbalance of evaporation relative to inflow, whereby increased evaporation and decreased inflow act to concentrate solutes into smaller volumes; and (ii) accelerated permafrost degradation, which enhances sublacustrine drainage while simultaneously leaching previously frozen solutes into lakes. We documented changes in nutrients [total nitrogen (TN), total phosphorus (TP)] and ions (calcium, chloride, magnesium, sodium) over a 25year interval in shrinking, stable, and expanding Subarctic lakes of the Yukon Flats, Alaska. Concentrations of all six solutes increased in shrinking lakes from 1985-1989 to 2010-2012, while simultaneously undergoing little change in stable or expanding lakes. This created a present-day pattern, much weaker or absent in the 1980s, in which shrinking lakes had higher solute concentrations than their stable or expanding counterparts. An imbalanced evaporation-to-inflow ratio (E/I) was the most likely mechanism behind such changes; all four ions, which behave semiconservatively and are prone to evapoconcentration, increased in shrinking lakes and, along with TN and TP, were positively related to isotopically derived E/I estimates. Moreover, the most conservative ion, chloride, increased >500% in shrinking lakes. Conversely, only TP concentration was related to probability of permafrost presence, being highest at intermediate probabilities. Overall, the substantial increases of nutrients (TN >200%, TP >100%) and ions (>100%) may shift shrinking lakes towards overly eutrophic or saline states, with potentially severe consequences for ecosystems of northern lakes.

Features of the elemental composition of plants of northern Western Siberian palsas

This paper reports the current state of lake and wetland ecosystems in the north of Western Siberia and describes the mechanisms of their formation and succession. Elemental composition of lake water and macrophytes of the four most typical subarctic lake ecosystems in Western Siberia were analysed using ICP MS. We selected the species of Menyanthes trifoliata L. as an example of the biogeochemical system. The general dynamics of concentration of the chemical elements in M. trifoliata L. in all four ecosystems demonstrate the minimal concentrations of rare-earth elements, of which the mobility in fresh waters and the bioavailability are low. Similar properties are exhibited by all tri and tetravalent hydrolysates. We also calculated, at each of the four stages of development of the lake ecosystems, the coefficients of biological accumulation of chemical elements by M. trifoliata L. (Kb) relative to the water. This revealed that the M. trifoliata L. strongly accumulates heavy metals, such as Pb, Zn, Sr and Co. The sources may be both global factors (atmospheric transport, water treatment, etc.) and various types of local pollution occurring as a result of anthropogenic impact on ecosystems of the north.