Post-glacial lake development and paleoclimate in the central Hudson Bay Lowlands inferred from sediment records

Hargan, Kathryn E.; Finkelstein, Sarah A.; Rühland, Kathleen M.; Packalen, Maara S.; Dalton, Andrew; Paterson, Andrew M.; Keller, W.; Smol, John P.

doi:10.1007/s10933-020-00119-z

Cited by 12 publications

(20 citation statements)

References 76 publications

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“…Almost 20 years later, our results in the same area indicate Chl a and TN values higher than either of these earlier studies (Table 1). This result is consistent with other studies that have indicated that Chl a values appear to be increasing and freshwater ecosystems have become more productive as a result of the rapid climate-driven changes affecting the Arctic (Hargan et al 2020;Michelutti et al 2005;Stuecker et al 2018). Since Chl a, phytoplankton biomass and nutrients are positively correlated to mean July temperature (Dranga et al 2018), small increases in temperature in the Arctic can have a major effect, especially in shallow water bodies that have been shown to respond rapidly to shifts in air temperatures (Rautio et al 2011).…”

Section: Discussionsupporting

confidence: 92%

Evidence of eutrophication in Arctic lakes

et al. 2021

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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). 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<sup>-1</sup>) 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. We hypothesize that the coupled effects of catchment characteristics and elevated local snow accumulation patterns promote higher nutrient leaching rates from the soils. We recommend further analysis and monitoring as eutrophication could become more widespread with ongoing climate change and the associated increases in temperature, precipitation, and catchment-lake coupling.

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Section: Discussionsupporting

confidence: 92%

Evidence of eutrophication in Arctic lakes

et al. 2021

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“…A subsequent increase in CAR during the late Holocene is also noted in other regional studies (Bunbury et al, 2012;Garneau et al, 2014;Loisel et al, 2014;O'Reilly et al, 2014). Available Holocene paleoclimate records derived from lacustrine pollen records in the HBL indicate wetter and cooler conditions after 3000 cal yr BP (Hargan et al, 2020;McAndrews et al, 1982). These conditions may have enhanced carbon accumulation by reducing rates of peat decomposition.…”

Section: Bog and Fen Carbon Accumulationsupporting

confidence: 60%

Linking testate amoeba assemblages to paleohydrology and ecosystem function in Holocene peat records from the Hudson Bay Lowlands, Ontario, Canada

Bysouth

Finkelstein

2020

The Holocene

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Peat cores from boreal bog and fen sites in the Hudson Bay Lowlands of Northern Ontario, Canada, were analysed to calculate Holocene carbon accumulation rates, and to show how testate amoeba taxonomic assemblages, inferred depths to water table, and four morpho-traits that may be linked to function (mixotrophy, aperture size, aperture position, and biovolume) changed since peatland initiation. Carbon accumulation rates were on average higher for the Holocene in the fen record (19.4 g C m−2 yr−1) in comparison with the bog record (15.7 g C m−2 yr−1), which underwent a fen-to-bog transition around 6900 cal yr BP. Changes in rates of carbon accumulation were most strongly driven by changes in rates of peat vertical accretion, with more rapid rates in the fen record. Carbon accumulation rates were highest following peatland initiation when reconstructed water tables were highest, and in the late Holocene, when water table positions were variable. Taxa with larger biovolumes and apertures were generally more abundant when reconstructed water tables were higher, most notably following peatland initiation. Mixotrophic taxa were more prevalent in drier conditions and in the bog record. Changing frequencies of morpho-traits suggest that testate amoebae may occupy a higher trophic position in the microbial food web during wetter periods, signaling the possibility of internal feedbacks between peatland ecohydrology and critical ecosystem functions including long-term carbon accumulation.

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“…Higher relative abundances of Ericaceae, Larix , and Betula pollen in the early portion of the record (Fig.4; Zone 1) are similar to other available records from the HBL, which suggest a regional succession from herbs and grasses to shrubs, followed by the establishment of a Picea -dominated landscape with decreased marine influence and wetland succession (i.e., coastal marshes to interior fens and bogs; McAndrews et al, 1982; Klinger and Short, 1996; Kettles et al, 2000; Hargan et al, 2020). Rare grains of more southern tree pollen taxa at this site (i.e., Acer, Juglans, Quercus, and Tsuga ; Supplementary Fig.…”

Section: Discussionsupporting

confidence: 75%

“…Sustained rich fen conditions at the site until 3200 cal yr BP take place in the context of warmer temperatures associated with the regional timing of the Holocene thermal maximum in the mid Holocene (8000–5000 cal yr BP), followed by cooling in the late Holocene and transition to the Neoglacial (4000–2500 cal yr BP; Viau and Gajewski, 2009; Hargan et al, 2020). The mid Holocene differed from the late Holocene because the incursion of dry Pacific and Arctic air masses was less frequent, leading to increased summer precipitation, as inferred from eastern North American δ 18 O, charcoal, and pollen records (Edwards et al, 1996; Carcaillet and Richard, 2000; Moos and Cumming, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Neoglacial cooling over the last four millennia (Viau and Gajewski, 2009; Hargan et al, 2020) is generally associated with lower rates of peatland initiation and lower apparent CARs in some HBL peat records (Kettles et al, 2000; Bunbury et al, 2012; O'Reilly et al, 2014; Packalen and Finkelstein, 2014; Bysouth and Finkelstein, 2020). In several records, the slowdown in peat CARs is associated with a shift from fen to bog conditions after 2500 cal yr BP.…”

Section: Introductionmentioning

confidence: 99%

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Ecohydrological controls on apparent rates of peat carbon accumulation in a boreal bog record from the Hudson Bay Lowlands, northern Ontario, Canada

et al. 2021

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A multiproxy Holocene record from a bog in the Hudson Bay Lowlands, northern Ontario, Canada, was used to evaluate how ecohydrology relates to carbon accumulation. The study site is located at a somewhat higher elevation and on coarser grained deposits than the surrounding peatlands. This promotes better drainage and thus a slower rate of carbon accumulation relative to sites with similar initiation age. The rate of peat vertical accretion was initially low as the site transitioned from a marsh to a rich fen. These lower rates took place during the warmer temperatures of the Holocene thermal maximum, confirming the importance of hydrological controls limiting peat accretion at the local scale. Testate amoebae, pollen, and plant macrofossils indicate a transition to a poor fen and then a bog during the late Holocene, as the carbon accumulation rate and reconstructed water table depth increased. The bacterial membrane lipid biomarker indices used to infer paleotemperature show a summer temperature bias and appear sensitive to changes in peat type. The bacterial membrane lipid biomarker pH proxy indicates a rich to a poor fen and a subsequent fen to bog transition, which are supported by pollen, macrofossil, and testate amoeba records.

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Post-glacial lake development and paleoclimate in the central Hudson Bay Lowlands inferred from sediment records

Cited by 12 publications

References 76 publications

Evidence of eutrophication in Arctic lakes

Evidence of eutrophication in Arctic lakes

Linking testate amoeba assemblages to paleohydrology and ecosystem function in Holocene peat records from the Hudson Bay Lowlands, Ontario, Canada

Ecohydrological controls on apparent rates of peat carbon accumulation in a boreal bog record from the Hudson Bay Lowlands, northern Ontario, Canada

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