ECR feature: Cindy Paquette on geographical gradients shaping zooplankton distribution

Cindy Paquette is a PhD student at the University of Quebec in Canada. She is an aquatic ecologist interested in the impact of climate change and human activities on lake aquatic environments. Here, Cindy shares her recent work on how zooplankton are structured at different spatial scales.

Cindy Paquette collecting zooplankton in Lac Croche (Station de Biologie des Laurentides, University of Montreal), QC – Canada.

Personal links. Research Gate

Institute. University of Quebec at Montreal, Department of Biological Sciences; McGill University, Department of Biology

Academic life stage. PhD student

Major research themes. I am a Biology student specializing in aquatic ecology, more specifically at the level of planktonic communities. I am interested in the consequences of climate change and human activities in the Anthropocene on lake aquatic environments. Currently, I am working on a project to evaluate how zooplankton communities relate to overall lake health as well as watershed factors like land use and cover type.

Current study system. I work on freshwater zooplankton. Zooplankton compose the heterotrophic planktonic group that feeds on the main energy mobilizers (phytoplankton and bacteria) in pelagic lake food webs. As primary consumers, zooplankton are in turn, the food supply for macroinvertebrate and fish predators, and thus a critical trophic link in the upward transfer of energy. Changes in zooplankton communities can thus be essential to lake ecosystem functioning given their central food web position, mediating bottom-up and top-down energy transfers. Moreover, zooplankton are also sensitive to anthropogenic impacts, being good integrators and indicators of water quality.

Recent JBI paper. Paquette, C., Gregory-Eaves, I. and Beisner, B.E. (2021), Multi-scale biodiversity analyses identify the importance of continental watersheds in shaping lake zooplankton biogeography. Journal of Biogeography, 48(9): 2298-2311.

Zooplankton collected in Fox Valley (SK) showed red pigmentation (left) while specimens from Lac Augustin (Qc) had green pigmentation (right).

Motivation behind this paper. Worldwide, Canada has the greatest number of and surface area covered by lakes. Lakes are thus an integral part of Canadian culture and global water sustainability. However, we do not have a complete picture of Canadian lakes’ health because evaluation of lakes is handled differently by each province, including to what degree they are affected by human activities. Nor do we know how they are likely to change with future climate change, again because the evaluation of lakes is handled regionally by provinces. My research was part of a network called LakePulse (, created to answer these questions by evaluating over 650 lakes across Canada in a consistent way with a wide variety of ecological parameters. My main motivation behind this paper was to explore dispersal-related processes behind zooplankton biogeographical patterns, with the objective to determine how zooplankton taxonomic and functional composition are structured at different spatial scales (e.g. Canadian ecozones or continental drainage basins) across one of the largest and freshwater-rich countries in the world.

Key methodologies. As part of the LakePulse network, we sampled 664 lakes across Canada over the course of three years, covering 12 ecozones and six continental drainage basins. For the first time, taxonomic and functional zooplankton biogeographical patterns were analysed at the pan-Canadian scale. Using the lens of traits (e.g. body size, feeding mode, habitat) permitted a common currency across a wide range of community taxonomic lists, by which to examine how Canadian lake plankton communities respond to and influence their environment and its functioning. We explored the role of spatial extent using a combination of zooplankton composition and diversity, including spatial or β-diversity. β-diversity compares species composition among lakes or regions and is a useful tool in conservation and biodiversity management as it enables identifying species or lakes critical for regional diversity maintenance. The combination of metrics and diversity dimensions we used revealed novel spatial patterns across Canadian lakes, especially at the continental drainage basin spatial scale.

Unexpected challenges. Sampling 664 lakes over the course of three summers was a great challenge. I participated in all three field campaigns (2017-2018-2019) and thus had the opportunity to sample personally over one hundred lakes across Canada. Field teams faced multiple challenges, from difficult lake access to bear encounters. More than 100 different variables were sampled at each lake, with many samples having to remain sufficiently cold or frozen while the field crews travelled to a new lake each day. We are very grateful to the landowners, including several First Nations, who made this sampling possible. This intensive field campaign taught me many skills and allowed me to meet incredible people across the country, all connected by the desire to protect Canada’s freshwaters and especially its lakes.

Mauro de Toledo performing zooplankton sampling in Alberta (Canada).

Major results. Our major finding was that zooplankton species and trait composition were best structured at the larger scale defined by continental watershed basins than at the regional scale of Canadian ecozones. We were expecting to find a latitudinal pattern in zooplankton diversity, with greater diversity in the south because of higher solar radiation levels, as had been observed in at least one other study. Surprisingly, we found an overall longitudinal pattern in local diversity, with eastern Canada showing greater diversity, and little latitudinal pattern. Our results pointed to the importance of physical barriers in species dispersal as the main diversity turnover seemed to occur at the Rocky Mountains, with diversity increasing when moving to the east as species accumulated across the country. Our results also showed that country-wide taxonomic β-diversity varied more than functional β-diversity, indicating real compositional shifts in species.

Next steps for this research. Our next step is to relate the spatial biogeographical patterns observed in this study to environmental factors in and around each lake. In addition to zooplankton community data, we also collected data on water quality (physical, chemical and biological variables), lake morphometry, human land use, and land cover type in each lake’s watershed. By relating these data, our goal will be to determine which local lake variables are most critical for zooplankton diversity across Canada. Going even further, we will also compare our contemporary crustacean zooplankton assemblages collected from the top sediments in each lake to pre-industrial assemblages that have accumulated in the sediments by analysing sub-fossil zooplankton remains from sediment cores. This will allow us to evaluate to what degree zooplankton communities have changed during the course of the Anthropocene.

Some lakes were particularly scenic to sample, like Chaunigan Lake, BC (Canada).

If you could study any organism on Earth, what would it be? I really enjoy working with plankton as they are plentiful and relatively easily studied as well as being charismatic in their own way. However, I also really enjoy being in the mountains. I would love to combine these passions and study zooplankton communities in alpine regions. Alpine lakes are unique in that they are particularly vulnerable to climate change, and are thus great systems to estimate how freshwater lakes will continue to change in the future.

Anything else to add? Plankton are great indicators of lake food web functioning, but they are also great because there are so many little-known fun facts about them to share at parties (post-pandemic, of course). In addition to zooplankton, one of my main passions is rock climbing. Rock can be formed in many ways, including by accumulating sediments containing the bodies of dead plankton throughout millions of years. Thus, in some places like the Sister Cliffs (UK) or Saint-Alban (Canada), the sedimentary rock forms cliffs where climbers can explore this unique rock type. I love the fun fact that it is possible to climb on plankton! 

Published by jbiogeography

Contributing to the growth and societal relevance of the discipline of biogeography through dissemination of biogeographical research.

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