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We provide the first assessment of regional water chemistry and plankton (phytoplankton and crustacean zooplankton) for a suite of lakes near the Sutton River region of the north-central Hudson Bay Lowlands (HBL). We use ordination analyses to examine the spatial variation in water chemistry and plankton across lakes, and to explore the factors that may explain this variation. Based on data collected during summer from 2009 to 2011, we found that in addition to geology, water chemistry was strongly influenced by a lake's proximity to salt water and the degree of permafrost development within its catchment. Phytoplankton composition varied across lakes based on differences in water depth and nutrient concentrations, with non-filamentous cyanobacteria and chlorophytes more common in shallow lakes, and deeper lakes dominated by planktonic diatoms or filamentous cyanophytes. Crustacean zooplankton community composition and richness in the HBL lakes was similar to communities found in Ontario lakes in...

A multi-proxy paleolimnological survey was performed on 13 lakes in the Hudson Bay Lowlands (HBL) of northern Ontario in order to provide a regional analysis of recent environmental changes in this poorly studied sub-Arctic region. In contrast to the amplified warming experienced by most of the circumpolar Arctic since the mid-19th century, the climate of the Hudson Bay (HB) region has remained relatively cool and stable for hundreds of years. However, since approximately the 1990s, the HBL has experienced rapid and large increases in air temperature and declines in sea ice. Diatom, cladoceran, and chironomid remains preserved in the recent (surface) and pre-1850 sediments of 13 lakes were used to examine whether this new climate regime has resulted in species assemblage changes across multiple trophic levels. Our results indicate clear limnological responses to warming among the freshwater biota of HBL lakes; however, the magnitude of this change varied among both biological indicators and sites...

There are two distinct views of the north: one as frontier, the other as homeland. —Thomas Berger (Berger, 1977) The general study region examined in this special issue is the drainage to the south...

Arctic and subarctic ecosystems have undergone considerable environmental changes in recent years as the result of climate warming. Fossil records of freshwater diatoms in lakes throughout the circumpolar Arctic, including the central Canadian Arctic treeline region, have revealed marked directional shifts in diatom assemblages in recent lake sediments. These algal changes have been linked to longer growing seasons, decreased duration of ice cover, and/or increased thermal stability. The effects of these recent environmental changes on higher trophic levels, such as the Cladocera, are still unclear. Using cladoceran remains preserved in the sediments of 50 lakes, which were previously examined for changes in diatoms, we show that significant changes in cladoceran species composition have occurred from pre-industrial times to the present. However, these changes are considerably muted compared to the more substantial changes observed in the diatom record. We found no consistent patterns of change i...

Changes in diatom assemblage composition since preindustrial times were analyzed in a landscape paleolimnological study of 50 lakes and also in a more detailed analysis of a dated sediment core from Slipper Lake in the Canadian central arctic treeline region. The most apparent taxonomic shift was toward a higher relative abundance of the planktonic Cyclotella stelligera complex and a lower relative abundance of benthic Fragilaria taxa (F. pinnata, F. construens var. venter, F. construens, and F. brevistriata) in the modern versus the older sediments. Diatom assemblage composition in Slipper Lake recorded a marked change in the top 5.0 cm (ca. mid-1800s) of the core with a clear shift to a more planktonic diatom assemblage characterized by higher percentages of the Cyclotella stelligera complex. Possible causative factors, such as recent anthropogenic acidification, nutrient enrichment, or atmospheric deposition of contaminants, do not appear sufficient to explain these species changes. Instead, t...

Diatoms and other siliceous microfossils were examined from a 386-cm-long peat core, covering the last ca. 7200 yr, from north-central Siberia to gain insights into peatland developmental history, ...