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Fifty-five paleolimnological records from lakes in the circumpolar Arctic reveal widespread species changes and ecological reorganizations in algae and invertebrate communities since approximately anno Domini 1850. The remoteness of these sites, coupled with the ecological characteristics of taxa involved, indicate that changes are primarily driven by(More)
[1] A new application of reflectance spectroscopy enables inferences of lake sediment chlorophyll a concentrations and hence of historical trends in lacustrine primary production. In a survey of six arctic lakes on Baffin Island (Nunavut, Canada), pronounced increases of spectrally-inferred chlorophyll a concentrations are consistently expressed in(More)
Thirty-four lakes and ponds on north-central Victoria Island (Arctic Canada) were examined in order to characterize the limnological conditions of these unstudied aquatic ecosystems, and to provide baseline data as part of a larger study monitoring future changes in climatically-sensitive high-latitude locations. Similar to several other arctic regions, the(More)
We document the rapid transformation of one of the Earth's last remaining Arctic refugia, a change that is being driven by global warming. In stark contrast to the amplified warming observed throughout much of the Arctic, the Hudson Bay Lowlands (HBL) of subarctic Canada has maintained cool temperatures, largely due to the counteracting effects of(More)
Arctic oases are regions of atypical warmth and relatively high biological production and diversity. They are small in area (<5 km(2) ) and uncommon in occurrence, yet they are relatively well studied due to the abundance of plant and animal life contained within them. A notable exception is the lack of research on freshwater ecosystems within polar oases.(More)
Multiple stressors to a shallow lake ecosystem have the ability to control the relative stability of alternative states (clear, macrophyte-dominated or turbid, algal-dominated). As a consequence, the use of remedial biomanipulations to induce trophic cascades and shift a turbid lake to a clear state is often only a temporary solution. Here we show the(More)
Numerous environmental pressures have precipitated long-term population reductions of many insect species. Population declines in aerially foraging insectivorous birds have also been detected, but the cause remains unknown partly because of a dearth of long-term monitoring data on avian diets. Chimney swifts (Chaetura pelagica) are a model aerial(More)
Few lakes in the Arctic preserve sediments older than Holocene age because of pervasive glacial scour during the last ice age. Here we present sediment diatom and geochemical records from a lake on east-central Baffin Island (CF8, Nunavut, Canada) that captures three successive interglacial periods within the last 200,000 years: a portion of marine isotope(More)
Recent climate change has been especially pronounced in the High Arctic, however, the responses of aquatic biota, such as diatoms, can be modified by site-specific environmental characteristics. To assess if climate-mediated ice cover changes affect the diatom response to climate, we used paleolimnological techniques to examine shifts in diatom assemblages(More)
Seabirds represent a well documented biological transport pathway of nutrients from the ocean to the land by nesting in colonies and providing organic subsidies (feces, carcasses, dropped food) to these sites. We investigated whether seabirds that feed at different trophic levels vary in their potency as biovectors of metals, which can bioaccumulate through(More)