Climate-driven regime shifts

Climate-driven regime shifts in the biological communities of arctic lakes

Original Douglas et al 1994

Arctic Lake Images

Click on an image below to open a higher resolution version.

Rock Basin Lake, Baird Inlet (east-central Ellesmere Island, Nunavut, Canadian High Arctic) was the site of the first detailed paleolimnological study from the circumpolar region, which used diatom and chrysophyte microfossils to track past climatic change.

As climatic change is predicted to be more pronounced in arctic regions, lakes in northern locations are especially sensitive.

Photograph: John P. Smol, Queen's University, August 1987

A typical lake from north-central Ellesmere Island, Nunavut, Canadian High Arctic. The central float of ice may persist throughout the summer during cool years in some lakes.

Photograph: Bronwyn Keatley, Queen's University, July 2003

A subarctic lake from northern Québec (Nunavik).

Photograph: Reinhard Pienitz, Université Laval, August 2002

Using a Glew Gravity Corer (developed at PEARL) to collect a vertical sample of lake sediments which can be extruded into slices for discrete samples.

Photograph: J.P. Smol

A mini-Glew gravity corer (developed by John Glew, PEARL) was used to collect a sediment core from a remote subarctic lake, Northwest Territories, Canada. Here the sample was retrieved off the pontoons of a helicopter.

Photograph: Kathleen Rühland, Queen's University

Once the sediment core has been obtained, it is sectioned into discrete layers. Each sedimentary layer contains biological microfossils that are representative of the environmental conditions present during the time at which they lived in the lake.

Photograph: Marianne Douglas, University of Toronto, 2003

Diploneis sp. Photograph: Daniel T. Selbie, Queen's University

Diatoms (siliceous algae) are abundant and diverse components of the biota of most lakes, ponds, and rivers, and preserve well in lake sediments. Different species are characteristic of different types of environments and the abundance of different species in the lake sediments can be used to determine past environmental conditions.

Navicula sp. Photograph: Kathleen Rühland, Queen's University

Chitinous head capsules of larval chironomids (non-biting midges, a type of insect) represent another type of biological indicator preserved in lake sediments.

Sergentia sp. Photograph: Jon Sweetman, Queen's University

Cladoceran zooplankton, such as the chydorids, are also well-preserved in lake sediments, as their carapaces are made of chitin.

Chydorus sp. Photograph: Jon Sweetman, Queen's University

PLEASE NOTE: A PDF copy of the study can be obtained from the Proceedings of the National Academy of Sciences, or contact Dr. John Smol at smolj@queensu.ca for a copy. High resolution images are available upon request.

Contact Information for authors:

John Smol

Email: smolj@queensu.ca

Tel: +1 613-533-6147

Alexander Wolfe