Supervised by:

Milla Rautio (Regular Member (Co-researcher))

Co-supervised by:

Milla Rautio (Regular Member (Co-researcher))

Research project description

Under-ice lake ecology from north-temperate to Arctic ecosystems

Introduction

More than half of the world’s lakes experience frozen winters with seasonal ice cover, providing benefits to society and the environment. However, lake surfaces are warming in response to global climate change. Many lakes experience longer summers with greater productivity, which may result in shorter ice-covered seasons with earlier winter hypoxia in cold-winter regions. Increasingly later ice-on and earlier ice-off directly affect lake ecology. Yet, while winter conditions are changing rapidly, the ecological consequences for winter-active (overwintering) lake biota remain largely unknown due to a historical lack of freshwater research in winter.

Objectives

Understanding the controls on animal overwintering under different winter conditions and the implications for lake communities is imperative to anticipate what ecological processes are at stake with climate warming and shortening ice-covered seasons. For my postdoctoral research, I investigate how small planktonic and benthic animals survive the winter in seasonally ice-covered lakes at various latitudes in North America, from north-temperate USA to boreal and Arctic Canadian regions. Through the characterisation of lipid (fatty acid) contents in zooplankton and benthos, I will (1) trace the origin of food resources and fat reserves sustaining winter-active organisms to evaluate relationships between winter performance, survival strategies and environmental conditions; and (2) quantify the availability of high-quality fat resources (nutritious food) to fish populations, especially when oxygen levels become low under lake ice.

Study Sites

Together with my research teams, I conduct a series of winter field campaigns in Vermont, USA (multiple sub-basins of a large north-temperate lake [Lake Champlain] that experience contrasting winter and ice conditions), Saguenay, Québec (seasonally ice-covered boreal lakes), and on Victoria Island, Nunavut (seasonally-ice covered Arctic lakes). This set of lakes spans a wide range of latitudes (~44ºN to ~70ºN) and winter severity, with typical ice-cover periods lasting for about two (northern Vermont) to five (boreal Québec) to ten (Nunavut) months. Lake communities are thus expected to employ different survival strategies to cope with winter.

Material and methods

This research combines traditional microscopy techniques (identification, enumeration, and biomass estimate) with lipidic profiles (absolute and relative quantities of 40 fatty acids) to evaluate winter performance and survival strategies in zooplankton and zoobenthic communities. Building on previous studies exploiting the use of fatty acids as biomarkers to trace energy flow in aquatic food webs, I will identify the origin of individual fatty acids in consumers and estimate proportions derived from algal, terrestrial, and bacterial biosynthesis. I will then analyse relationships between zooplankton/benthos densities, survival strategies (food/fat origin and fat accumulation) and environmental conditions (e.g., ice cover duration).

References

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Research Site Coordinates