Enhanced algal abundance in northwest Ontario (Canada) lakes during the warmer early-to mid-Holocene period

Karmakar, Moumita; Leavitt, Peter R.; Cumming, Brian F.

doi:10.1016/j.quascirev.2015.06.025

Cited by 11 publications

(9 citation statements)

References 61 publications

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“…In general, we demonstrate that limnological conditions were more optimal for algae over the last ~4500 years than in the preceding millennia. This pattern is in stark contrast to those seen in lakes from northwest Ontario, where paleolimnological studies have linked the warmer HTM to enhanced lake-water production (Moos and Cumming, 2009;Karmakar et al, 2015b). In Charland Lake, such changes were evident, but small in comparison, and did not indicate the warmer temperatures of the HTM directly influenced lake-water production.…”

Section: Discussioncontrasting

confidence: 77%

“…yr BP. The onset of warmth is ~1000 years later than recorded in northwest Ontario Cumming, 2011, 2012;Moos et al, 2009;Karmakar et al, 2015aKarmakar et al, , 2015b. Differences between our findings and Liu's (1990) results may be because of the more rigorous carbon dating model used in our study as our pollen analysis agrees with Liu's study quite well.…”

Section: Discussionsupporting

confidence: 52%

“…This estimate was calculated using a modern analog technique (MAT) calibration based on fossil pollen and a regional set of modern pollen and climate data (Moos and Cumming, 2011). Associated dryer conditions resulted in lower lake levels, increased algal production, an eastward shift of the prairie-forest ecotone, and an increase in fire activity (Moos et al, 2009;Cumming, 2011, 2012;Karmakar et al, 2015aKarmakar et al, , 2015b. Despite this research, there has been little work examining the HTM of northeastern Ontario, Canada, which is a problem this paper seeks to address.…”

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confidence: 99%

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Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

et al. 2019

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Historical changes in Holocene climate in northeastern Ontario were quantified using analyses of sedimentary pollen, diatoms, and pigments in a small boreal lake. Modern analog reconstructions of average temperature from Holocene pollen assemblages of Charland Lake showed temperature was ~2°C warmer than present conditions ~7800–4500 cal. yr BP, a time period consistent with the Holocene thermal maximum (HTM). Pollen data suggest a two-phase HTM: warm and dry conditions based on the presence of primarily Pinus spp., followed by warm and wet conditions based on increases in cedar. Overall, algal production was low during the HTM, as reflected by low concentrations of pigments and diatoms. In the late HTM, increases in cedar pollen and planktonic diatoms suggest sustained increases in water levels for the remainder of the Holocene. During the Post-HTM Period (~4500–2000 cal. yr BP), a period that was warmer than today but cooler than the HTM, overall pigment production was significantly higher than all other periods. However, changes in diatom species composition suggest this period was not uniform, with variation occurring between diatoms indicative of higher and lower nutrient levels. The last ~2000 cal. yr BP was less productive than the Post-HTM Period but more productive than the HTM with higher production from diatoms and cyanobacteria. This study suggests that the relationship between climate and lake water production can be quite complex, and that changes in temperature, precipitation, light, lake levels, and mixing patterns are among factors that are related to changes in subfossil phototroph assemblages.

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Section: Discussioncontrasting

confidence: 77%

Section: Discussionsupporting

confidence: 52%

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confidence: 99%

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Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

et al. 2019

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“…Contrasting environmental conditions between the Northgrippian and the Meghalayan stages likely account for the observed differences in accretion rates. During the Northgrippian, increased lake productivity in a warmer drier climate, with a longer aquatic growing season, for example, may have contributed to eutrophication ( Moss et al, 2011 ), as has been reported for the mid-Holocene for lakes in New York State, USA ( Mullins, 1998 ) and Northern Ontario, Canada ( Karmakar et al, 2015 ; Moos et al., 2009 ), and suboxic conditions which would in turn slow the rate of oxidative Fe and Mn precipitation and concretion growth. In addition, lower water levels would have diminished the hydraulic gradients that drive Fe(II)- and Mn(II)-rich groundwater fluxes into the lake.…”

Section: Discussionmentioning

confidence: 96%

Growth rates for freshwater ferromanganese concretions indicate regional climate change in eastern Canada at the Northgrippian-Meghalayan boundary

Hayles

Cornett

et al. 2021

The Holocene

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The existence of freshwater ferromanganese concretions has been known for decades, but we are not aware of a generally accepted explanation for their formation, and there has been little research into their potential use as records of Holocene climate and paleohydrology. A conceptual model is presented to describe the environmental and geochemical processes which result in the formation and growth of freshwater ferromanganese concretions. In order to evaluate their potential as historical geochemical records, a concretion from Magaguadavic Lake, New Brunswick, Canada is the focus of a detailed geochronological and geochemical investigation. The radiocarbon data provide a coherent growth curve and a maximum age for the concretion of 8448 ± 43 years, consistent with the establishment of Magaguadavic Lake as a stable post-glacial lacustrine system. The data suggest accretion rates of 1.5 and 3.4 mm per 1000 years during the Northgrippian and Meghalayan stages of the Holocene, respectively. The abrupt change in growth rate observed at the stage boundary may be an indicator of Holocene climate change. These features are consistent with inferences from previous research that warmer climate in the Northgrippian led to eutrophication in some lakes in eastern North America. The results confirm that freshwater Fe–Mn concretions may yield important information about past climatic and environmental conditions.

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“…Increases in effective moisture because of cooler temperatures between ~4000-2000 cal yr BP (Shuman and Marsicek, 2016;Viau and Gajewski, 2009) would have likely raised water levels high enough for the observed increases in planktic taxa in Green Lake Core 1 followed by a similar rise in Green Lake Core 2 ~2000 cal yr later. In addition, increases in water-levels after ~4000 cal yr BP would have likely resulted in lower water retention times in Hogsback and Green lakes which would have reduced the amount of nutrients available for the phototroph community (Karmakar et al, 2015b;Moos et al, 2005Moos et al, , 2009. Therefore, higher lake-levels and -volumes during the middle Holocene also contributed to regional oligotrophication alongside declines in temperatures.…”

Section: Middle and Late-holocene Climate Of Northeast Ontariomentioning

confidence: 99%

Basin-specific records of lake oligotrophication during the middle-to-late Holocene in boreal northeast Ontario, Canada

2021

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Descriptions of regional climate expression require data from multiple lakes, yet little is known of how variation in records within morphometrically complex lakes may affect interpretations. In northeast Ontario (Canada), this issue was addressed using records of pollen, pigments, and diatoms in three sediment cores from two small boreal lakes spanning the last ~6000 years. Pollen analysis suggested warm conditions between ~6000 and ~4000 cal yr BP, coherent with previous assessments from boreal eastern Ontario and western Quebec. Analysis of phototrophic communities from fossil pigments and diatom valves suggested relatively eutrophic conditions with lower lake-levels during this interval. Generalized additive model trends identified significant regional changes in pollen assemblages and declines in pigment concentrations after ~4000 cal yr BP consistent with cooler and wetter climate conditions that resulted in regional lake oligotrophication and increased lake levels during the late-Holocene. Despite contemporaneous changes in pollen and pigment biomarkers across lakes, cores collected from adjacent basins of the same lake (Green Lake) did not show similar trends in fossil pigments likely reflecting preferential deposition of clay-rich allochthonous material in the deeper central basin and suggesting that regional signals in climate may be complicated by lake- or basin-specific catchment processes.

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Enhanced algal abundance in northwest Ontario (Canada) lakes during the warmer early-to mid-Holocene period

Cited by 11 publications

References 61 publications

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

Growth rates for freshwater ferromanganese concretions indicate regional climate change in eastern Canada at the Northgrippian-Meghalayan boundary

Basin-specific records of lake oligotrophication during the middle-to-late Holocene in boreal northeast Ontario, Canada

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