Diatom responses to 20th century climate warming in lakes from the northern Urals, Russia

doi:10.1016/j.palaeo.2007.10.001

Palaeogeography, Palaeoclimatology, Palaeoecology

Volume 259, Issues 2–3, 24 March 2008, Pages 96-106

https://doi.org/10.1016/j.palaeo.2007.10.001 Get rights and content

Abstract

Changes in diatom assemblages and spheroidal carbonaceous particle (SCP) profiles during the last 200 years in ²¹⁰Pb-dated sediment cores from five remote arctic and sub-arctic lakes in the northern Urals were analysed. The study area covers a large territory from arctic tundra in the north to boreal forest on the western slopes of the Ural mountains in the south. pH was reconstructed using a diatom-based model. The degrees of compositional turn-over and rates-of-change were estimated numerically. The 20th century diatom floristic shifts, the rise in diatom accumulation rates and the rates of diatom compositional change in the northern Ural lakes correlate well with June temperature in the region and with the overall circum-arctic temperature increase from the 1970s. The main driving force behind diatom compositional shifts in the study lakes are the changes in the duration of ice-free season, timing of water turn-over and stratification periods and habitat availability. Changes in spheroidal carbonaceous particles show no pronounced effect on diatom assemblages. Pollution is restricted to regional sources originating mainly from the Vorkuta coal industry. Changes in diatom plankton are more pronounced than changes in diatom benthos. There is no clear north–south gradient in degree of compositional changes, with greatest changes occurring in Lake Vankavad situated in northern boreal forest. The degree of the 20th century diatom changes in Lake Vankavad is greater than in most circum-arctic and sub-arctic lakes from northern Europe and Canada.

Introduction

The 20th century global air temperature rise north of 60° N is well documented with warming of the order of 1.5 °C being observed in the periods between approximately 1915 and 1940 and from the end of 1960s until 2000 (Moritz et al., 2002, Jones and Moberg, 2003). The Arctic is warming at about twice the rate of the rest of the planet (ACIA, 2004) and the effects of climate change will be amplified in the north due to positive feedbacks including cryospheric processes such as glacier retreat, ice thinning, permafrost degradation and albedo changes (Giorgi and Mearns, 2002). Climate warming is now detectable in various terrestrial and aquatic arctic ecosystems including lakes and ponds (Douglas et al., 1994, Jones and Birks, 2004, Smol et al., 2005, Solovieva et al., 2005). However, spatial and temporal expression of arctic warming is highly variable due to regional differences in continentality, ocean heat transport, glacier and sea ice distribution, topography and vegetation (Smol et al., 2005).

Instrumental records of mean annual air temperature from the northern Urals do not show a distinct temperature increase within the 20th century. However, there is an increase in the summer temperature, notably in June and August–September, leading to an increase in the duration of the ice-free season (Solovieva et al., 2005). In this paper we examine the response of diatom assemblages to the 20th century summer warming in five lakes from the northern Ural region west of the Ural mountains using both limnological and palaeolimnological methods. Some of the lakes have been studied in the past. For instance, a recent comprehensive survey of Lake Mitrofanovskoe, edited by Drabkova and Trifonova (1994), includes research on the hydrology, water chemistry, phyto- and zooplankton, zoobenthos and fish populations. Lake Vanuk-ty has also been studied in detail (Belyaev et al., 1966). However, these studies provide mostly qualitative data over one or two years, with no continuous monitoring of the lakes. The Holocene history of Lake Vankavad was examined by Sarmaja-Korjonen et al. (2003) and its pollution history was reconstructed by Solovieva et al. (2002). Recent palaeolimnological changes in Lakes Mitrofanovskoe and Vanuk-ty were analysed by Solovieva et al. (2005).

Here we use the data from the above studies and, with additional data from two other sites, apply further numerical analysis to statistically assess 20th century changes in the diatom flora extending our study to sub-arctic lakes. One of the aims of the study was to test whether sub-arctic forest lakes respond to the 20th century warming in a similar fashion to arctic tundra lakes. As all the lakes are remote with no industry or permanent settlements in the vicinity, the diatom assemblages might be affected either by a long-distance atmospheric contamination or by changes in climate. This paper examined both scenarios. Sedimentary records of spheroidal carbonaceous particles (SCPs) were used as a proxy for atmospheric contamination.

Section snippets

Study area and study lakes

The study area covers a large, mostly lowland plain west of the Urals and includes lowland arctic shrub tundra with permafrost in the north and larch- and spruce-dominated northern boreal forest on the western slopes of the Urals in the south (Fig. 1). The area is underlain by Permian rocks and Quaternary deposits (Vlasova, 1976). Relief is hilly, with maximum altitudes reaching 230 m a.s.l. Climate is severe with an eight- to nine-month winter period (mean monthly temperatures below 0 °C). The

Methods

Sediment cores were collected using a Glew corer (Glew, 1989) from the deepest point of the lakes, the dates of sampling are shown in Table 1. The details of sediment extrusion, water sampling and water-chemistry analysis are given in Solovieva et al. (2002), Sarmaja-Korjonen et al. (2003) and Solovieva et al. (2005).

All sediment cores were analysed for ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs and ²⁴¹Am by direct gamma assay using Ortec HPGe GWL series well-type coaxial low background intrinsic germanium detectors (

Core chronologies

At all sites equilibrium between supported and unsupported ²¹⁰Pb, corresponding to ca. 100–120 years of accumulation, was reached at depths of between 5 and 16 cm (Table 2). At Lakes Vankavad and Vanuk-ty there were irregularities in the unsupported ²¹⁰Pb activity versus depth profiles, indicating non-uniform sedimentation rates. ²¹⁰Pb dates were therefore calculated using the CRS dating model (Appleby, 2001). All ²¹⁰Pb-based chronologies are in good agreement with the independently determined

Discussion

As all the lakes are remote with no permanent settlements in the catchments, there are no sources of local pollution, although there is some regional pollution originating from the Varkuta coal industry. There is also no evidence for acidification or eutrophication from diatom changes (Solovieva et al., 2002, Sarmaja-Korjonen et al., 2003, Solovieva et al., 2005). In all lakes, except for Lake Moreju, the major compositional changes predate the peaks in SCPs and the SCP profiles are not

Conclusions

The studied lakes appear to show no effect from local and regional pollution and atmospheric contamination.

The 20th diatom floristic shifts, the rise in diatom accumulation rates and the rates of diatom compositional change in the northern Ural lakes correlate well with the 1970s rise in June temperature in the region and with the overall circum-arctic temperature increase from the 1970s.

The main driving force behind diatom compositional changes in the study lakes are the changes in the

Acknowledgements

This is a contribution to the NERC project to Dr. V. J. Jones (NER/B/S/2000/00733). L. Nazarova was funded by a Royal Society/NATO travel scholarship. This is also a contribution to EU-funded SPICE (ICA2-CT-2000-10018) and TUNDRA (ENV4-CT97-0522) projects. Water-chemistry data were analysed in the Kola Science Centre, Apatity, Russia. We would like to thank everyone who helped with the fieldwork, namely Vasili Ponomarev, Valeri Illarionov, Kazimir Anet'ko, Leonid Nosov and Alexander Konobratkin.

References (53)

AndreevA.A. et al.
Holocene environmental history recorded in Lake Lyadhej-To sediments, polar Urals, Russia
Palaeogeography Palaeoclimatology Palaeoecology
(2005)
BindlerR. et al.
Pb isotope ratios of lake sediments in West Greenland: inferences on pollution sources
Atmospheric Environment
(2001)
PrenticeI.C.
Multidimensional scaling as a research tool in Quaternary palynology: a review of theory and methods
Review of Palaeobotany and Palynology
(1980)
ACIA
Impacts of a warming Arctic; Arctic Climate Impact Assessment
(2004)
Annual Reports on Meteorology. 1920–2001. Center of Hydrometeorology and Environmental Monitoring, Komi Republic. 987...
ApplebyP.G.
Chronostratigraphic techniques in recent sediments
ApplebyP.G. et al.
Pb-210 dating by low background gamma-counting
Hydrobiologia
(1986)
BattarbeeR.W. et al.
The use of electronically counted microspheres in absolute diatom analysis
Limnology and Oceanography
(1982)
BattarbeeR.W.J.S. et al.

BriffaK.R. et al.

Unusual 20th-century summer warmth in a 1000-year temperature record from Siberia

Nature

(1995)

CameronN.G. et al.

Surface-sediment and epilithic diatom pH calibration sets for remote European mountain lakes (AL:PE Project) and their comparison with the Surface Waters Acidification Programme (SWAP) calibration set

Journal of Paleolimnology

(1999)

ComisoJ.C.

Warming trends in the Arctic from clear sky satellite observations

Journal of Climate

(2003)

CremerH. et al.

Paleolimnological reconstructions of Holocene environments and climate from Lake Lyadhej-To, Ural Mountains, Northern Russia

Arctic, Antarctic and Alpine Research

(2004)

DouglasM.S.V. et al.

Marked post-18th century environmental-change in high-arctic ecosystems

Science

(1994)

DrabkovaV.G. et al.

Gidrokhimiya ozer. (Hydrochemistry of lakes)

GetsenM.V. et al.

Algologicheskaya flora Bol's hezemel's koi tundry v usloviyax antropogennogo vozdeistviya

GiorgiF. et al.

Calculation of average, uncertainty range, and reliability of regional climate changes from AOGCM simulations via the “reliability ensemble averaging” (REA) method

Journal of Climate

(2002)

GlewJ.R.

A new trigger mechanism for sediment samples

Journal of Paleolimnology

(1989)

GrimmE.C. et al.

Fossil-pollen evidence for abrupt climate changes during the last 18,000 years in eastern North America

Climate Dynamics

(1992)

JonesP.D. et al.

Hemispheric and large-scale surface air temperature variations: an extensive revision and an update to 2001

Journal of Climate

(2003)

JonesV.J. et al.

Lake-sediment records of recent environmental change on Svalbard: results of diatom analysis

Journal of Paleolimnology

(2004)

KitchellJ.A. et al.

Testing for equality of rates of evolution

Paleobiology

(1987)

KorholaA. et al.

A multi-proxy analysis of climate impacts on recent developments of subarctic lake Saanajävri in Finnish Lapland

Journal of Paleolimnology

(2002)

KrammerK. et al.

Bacillariophyceae

(1986–1991)

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Diatom responses to 20th century climate warming in lakes from the northern Urals, Russia

Abstract

Introduction

Section snippets

Study area and study lakes

Methods

Core chronologies

Discussion

Conclusions

Acknowledgements

Palaeogeography Palaeoclimatology Palaeoecology

Atmospheric Environment

Review of Palaeobotany and Palynology

Impacts of a warming Arctic; Arctic Climate Impact Assessment

Chronostratigraphic techniques in recent sediments

Pb-210 dating by low background gamma-counting

Hydrobiologia

The use of electronically counted microspheres in absolute diatom analysis

Limnology and Oceanography

Unusual 20th-century summer warmth in a 1000-year temperature record from Siberia

Nature

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Journal of Paleolimnology

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Journal of Climate

Paleolimnological reconstructions of Holocene environments and climate from Lake Lyadhej-To, Ural Mountains, Northern Russia

Arctic, Antarctic and Alpine Research

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Science

Gidrokhimiya ozer. (Hydrochemistry of lakes)

Algologicheskaya flora Bol's hezemel's koi tundry v usloviyax antropogennogo vozdeistviya

Calculation of average, uncertainty range, and reliability of regional climate changes from AOGCM simulations via the “reliability ensemble averaging” (REA) method

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