Regional climate changes drive increased scaled-chrysophyte abundance in lakes downwind of Athabasca Oil Sands nitrogen emissions

  • Graham R. Mushet
  • Kathleen R. Laird
  • Biplob Das
  • Brittany Hesjedal
  • Peter R. Leavitt
  • Kenneth A. Scott
  • Gavin L. Simpson
  • Björn Wissel
  • Jared D. Wolfe
  • Brian F. Cumming
Original paper
  • 42 Downloads

Abstract

Several limnological and paleolimnological investigations have linked enhanced atmospheric nitrogen (N) deposition to nutrient enrichment and increased primary production. The Athabasca Oil Sands Region (AOSR) in northeast Alberta, Canada is a significant source of N emissions, particularly since development intensified during the 1990s, and recent paleolimnological investigations provide evidence of increased lake production in adjacent areas subject to enhanced N deposition. The AOSR, however, has also experienced atmospheric warming since ca. AD 1900, and therefore the relative effects of nutrient deposition and climate changes on lake production remain unclear. We undertook a factorial-design paleolimnological assessment of 16 lakes in northwest Saskatchewan to quantify changes in abundance and species composition of scaled chrysophytes over the past 100 years. Study sites included both N-limited and P-limited lakes within control regions, as well as lakes that receive enhanced N deposition from the AOSR. We hypothesized that a change in algal communities within N-limited AOSR-impacted lakes, without concurrent changes in the other lake groups, would suggest AOSR-derived N as a driver of enhanced primary production. Instead, marked increases in concentrations of scaled chrysophytes, mainly Mallomonas crassisquama, occurred in the recent sediments in cores from all four lake groups (N-limited vs. P-limited, impacted vs. control), suggesting that regional climate change rather than N deposition was the paramount process enhancing chrysophyte production. Because chrysophyte abundances tended to be higher in deep, lower-pH lakes, and chrysophyte time series were fit best by lake-specific generalized additive models, we infer that climate effects may have been mediated by additional catchment and/or lake-specific processes.

Keywords

Athabasca Oil Sands Nitrogen deposition Climate change Regional warming Scaled chrysophytes 

Supplementary material

10933_2017_9987_MOESM1_ESM.docx (41 kb)
ESM Fig. S1Mean annual air temperature recorded in Fort McMurray (Alberta, Canada) since ~ 1900. Dashed line indicates the record mean. Data available online at: http://www.ec.gc.ca/dccha-ahccd/ (DOCX 41 kb)
10933_2017_9987_MOESM2_ESM.docx (1.4 mb)
ESM Fig. S2Total 210Pb activities (dashed line), Constant Rate of Supply (CRS) estimated dates and error (filled circles), and age depth models via monotonic cubic spline for all sixteen study lakes in northwest Saskatchewan (red line). r2 is for total 210Pb activity fit to a first order exponential decay. Core chronologies are organized by the four a priori lake groups: NI N-limited or N and P co-limited impact lake, PI P-limited impact lake, NR N-limited or N and P co-limited reference lake, PR P-limited reference lake (DOCX 1450 kb)
10933_2017_9987_MOESM3_ESM.docx (750 kb)
ESM Fig. S3Chrsyophyte scale concentrations and % carbon in the sediment cores from the sixteen study lakes in northwest Saskatchewan. A) N-limited or N and P co-limited impact lakes B) P-limited impact lakes C) N-limited or N and P co-limited reference lakes D) P-limited reference lakes (DOCX 749 kb)
10933_2017_9987_MOESM4_ESM.docx (196 kb)
ESM Fig. S4GAM smoothers extracted from the Factorial model by group for the S-to-D index time series. Shaded bands represent the upper and lower 95% confidence intervals for each model. NI N-limited or N and P co-limited impact lakes, PI P-limited impact lakes, NR N-limited or N and P co-limited reference lakes, PR P-limited reference lakes (DOCX 195 kb)
10933_2017_9987_MOESM5_ESM.docx (569 kb)
Supplementary material 5 (DOCX 569 kb)

Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  • Graham R. Mushet
    • 1
  • Kathleen R. Laird
    • 1
  • Biplob Das
    • 2
  • Brittany Hesjedal
    • 3
  • Peter R. Leavitt
    • 3
    • 4
  • Kenneth A. Scott
    • 5
  • Gavin L. Simpson
    • 3
  • Björn Wissel
    • 3
  • Jared D. Wolfe
    • 3
  • Brian F. Cumming
    • 1
  1. 1.Paleoecological Environmental Assessment and Research Laboratory, Department of BiologyQueen’s UniversityKingstonCanada
  2. 2.Saskatchewan Water Security AgencyReginaCanada
  3. 3.Limnology Laboratory, Department of BiologyUniversity of ReginaReginaCanada
  4. 4.Department of Biology, Institute of Environmental Change and SocietyUniversity of ReginaReginaCanada
  5. 5.Saskatchewan Ministry of EnvironmentReginaCanada

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