Contrasting ecological response to
climatic warming in Arctic lakes
with low and high diatom
biodiversity
Sarah Finkelstein
Department of Geography
University of Toronto
&
Konrad Gajewski
Department of Geography
University of Ottawa
Key objectives
• Explain spatial variability in
freshwater ecosystem responses to
warming
• Use a functional perspective
• Provide regional impact assessments
The paleoecological approach
S.Finkelstein
• Science of past
ecological changes
• Based on sediment
records and
microfossils
• “Experiments” to
determine responses
to climatic changes
S.Finkelstein
www.umich.edu
1850
Phycotech.com
S.Finkelstein
Diatom functional types
EPIPHYTES
Achnanthaceae
Sellaphora
seminulum
Navicula
submuralis
Acidophiles/bryophiles
(moss flora)
FRAGILARIOIDS
(benthic/tychoplank.)
PLANKTONICS
Diatom communities in Arctic
lakes… what’s going on?
• Increases in diversity and
production
• Changes in species composition Æ
new communities
Circum-Arctic diatom
profiles: recent assemblage
shifts
Large
changes
Small or no
changes
Smol, J.P. et al.
2005. PNAS.
Research questions
1. Does this variability reflect a
climate gradient or…
2. An ecological gradient?
– Functional response to a new climate
– Depends on algal diversity, production
or habitat availability
Arctic warming: spatial patterns
ACIA, 2004
NOAA State
of the Arctic
Report, Oct.
2006
Mar-Jun 2005
2007 NOAA Arctic Report Card
Feb-Apr 2006
Dec 2006 – May 2007
Research questions
1. Does this variability reflect a
climate gradient or…
2. An ecological gradient?
– Functional response to a new climate
– Could depend on algal diversity,
production or habitat availability
Biodiversity and ecosystem function
(e.g., magnitude of community
change in response to new climate)
J.B. Maxwell (1980)
Climate of the Canadian
Arctic Islands
PW02
PW03
Geological gradients
across PoW produce
ecological gradients
PW02
PW03
• PW03: Shield rocks, lush
shoreline vegetation (esp.
mosses). HIGH diatom
diversity.
• PW02: Conglomerate
(mixed mineralogy), low
plant cover and low
nutrient availability. LOW
diatom diversity.
Sample site
Map: Dyke et al., 1992 (GSC)
PW02
PW03
Biodiversity and ecosystem
function (e.g., response to new
climate)
PW03
PW02
Conclusions
• Importance of longer time scales
and smaller spatial scales to
understand regional impacts
• More data required to understand
functional implications of warming
Acknowledgements
• Funding:
–
–
–
–
–
NSERC
CFCAS
Polar Continental Shelf Project
University of Toronto Connaught Award
Canadian Foundation for Innovation
• Lab work:
– B. Podritske
– M.-C. Fortin
– T. Paull
Spatio-temporal
variability in
Holocene climatic
changes
Kaufman et al., 2004, QSR.