title: Distribution and diversity of diatom assemblages in surficial sediments of shallow lakes in Wapusk National Park (Manitoba, Canada) region of the Hudson Bay Lowlands.
abstract: The hydrology of shallow lakes (and ponds) located in the western Hudson Bay Lowlands (HBL) is sensitive to climate warming and associated permafrost thaw. However, their biological characteristics are poorly known, which hampers effective aquatic ecosystem monitoring. Located in northern Manitoba along the southwestern coast of Hudson Bay, Wapusk National Park (WNP) encompasses numerous shallow lakes representative of the subarctic zone. We analyzed the distribution and diversity of diatom (microscopic algae; class Bacillariophyceae) assemblages in surficial sediments of 33 lakes located in three different ecozones spanning a vegetation gradient, from NE to SW: the Coastal Fen (CF), the Interior Peat Plateau (IPP), and the Boreal Spruce Forest (BSF). We found significant differences (P < 0.05) in diatom community composition between CF and IPP lakes, and CF and BSF lakes, but not between IPP and BSF lakes. These results are consistent with water chemistry measurements, which indicated distinct limnological conditions for CF lakes. Diatom communities in CF lakes were generally dominated by alkaliphilous taxa typical of waters with medium to high conductivity, such as Nitzschia denticula. In contrast, several IPP and BSF lakes were dominated by acidophilous and circumneutral diatom taxa with preference for low conductivity (e.g., Tabellaria flocculosa, Eunotia mucophila, E. necompacta var. vixcompacta). This exploratory survey provides a first detailed inventory of the diatom assemblages in the WNP region needed for monitoring programs to detect changes in shallow lake ecosystems and ecozonal shifts in response to climate variations.
authors.affiliation: Département de géographie Université Laval Québec City QC Canada G1V 0A6; Centre d'études nordiques Université Laval Québec City QC Canada G1V 0A6.
authors.forename: Olivier
authors.initials: O
authors.lastname: Jacques
authors.affiliation: Département de géographie Université Laval Québec City QC Canada G1V 0A6; Centre d'études nordiques Université Laval Québec City QC Canada G1V 0A6.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bouchard
authors.affiliation: Department of Biology University of Waterloo Waterloo ON Canada N2L 3G1.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: MacDonald
authors.affiliation: Department of Biology University of Waterloo Waterloo ON Canada N2L 3G1.
authors.forename: Roland I
authors.initials: RI
authors.lastname: Hall
authors.affiliation: Department of Geography and Environmental Studies Wilfrid Laurier University Waterloo ON Canada N2L 3C5.
authors.forename: Brent B
authors.initials: BB
authors.lastname: Wolfe
authors.affiliation: Département de géographie Université Laval Québec City QC Canada G1V 0A6; Centre d'études nordiques Université Laval Québec City QC Canada G1V 0A6.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Pienitz
keywords: Diatoms; Hudson Bay Lowlands; Limnology; Monitoring; Shallow lakes; Wapusk National Park