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Climate change and subsequent change in species diversity is already under way. In different corners of the Arctic, however, climate change progresses in different ways. In the Scandinavian mountains in Finnish Lapland, the climate is warming and, at the same time, the amount of rain is increasing, while in Svalbard, warming is intense, but the precipitation does not increase at the same rate as temperature. Local conditions are relevant for Arctic species colonizing lakes and ponds in harsh Arctic environments where water is very cold and the entire mass of water is often frozen in winter. Many lakes are located in the permafrost region, which stabilizes lake temperatures and affects water movements. The warming climate poses real challenges for Arctic species as the polar regions begin to melt at an accelerating rate.

The changing climate exposes animals to temperatures and conditions that they have not experienced before. In order to understand change in the Arctic, we need to look back in time, understand this moment and, based on these, try to predict how the region will change in the future and which species in the region will survive. Each species and habitat has its unique characteristics, which influence how well species survive in the face of climate change.

The new method developed in this dissertation is based on calculation of the risk of species-specific extinction, based on the unique variation in nature and species.

“A new method is needed for biodiversity research, because environmental change causes species loss and species composition changes that occur unnoticed by humans, beneath the surface of lakes, in the remote area of roadless tundra, in the wilderness, in our northern lakes”, Hanna-Kaisa Lakka says.

Eat or be eaten - Extreme survival strategy in use in Svalbard

To survive in the Arctic regions, animals must grow to their reproductive size and ensure reproduction. How can survival of the species be ensured if the only representative of the species lives in a small pond that freezes up totally in winter? The freshwater crustacean, Arctic tadpole shrimp (Lepidurus arcticus) has its own solutions to this problem, such as parthenogenesis, or asexual reproduction, as well as frost and desiccation resistant resting eggs. A third interesting characteristic of this species is cannibalism, which is a proven strategy for survival in other Arctic animals as well.

Increasing precipitation and warming in Finnish Lapland, caused by climate change, allows southern species to move into the region. The cold-adapted endangered crustacean is in trouble and at risk to invasive predators. Its extreme strategies for survival no longer help in this case, and since its population sizes are small, it is more likely to be prey to invading predators than be eaten by its conspecifics.

Crustaceans are sensitive to changes in environmental conditions

Endangered Arctic crustaceans living in cold conditions of lakes and ponds were used as model organisms in this thesis. To demonstrate the cause-effect relationships of climate change, cold-adapted species that combine underwater and surface biodiversity are important research topics. Species distributions shift towards mountain peaks and polar regions as a result of climate change.

In the Scandinavian mountains, aquatic species cannot spread further north without crossing the sea, as they colonize the most Arctic habitats in Fennoscandia. If the population of the species does not adapt, or is not able to migrate, it will be lost. In areas where average temperatures for the year are near zero, true Arctic species are at risk because they lose their competitive advantage to southern species.

Studies at the University of Helsinki and, in particular, courses at Kilpisjärvi Biological Station and at the University of Svalbard (UNIS) provided a great framework for developing as an expert in Arctic waters. Professor Stephen Coulson (UNIS) taught Hanna-Kaisa Lakka Arctic Biology in Svalbard. The research has been conducted in collaboration with several Finnish and Norwegian universities.

The dissertation is published in JYU Dissertation series, number  295, Jyväskylä, 2020.
ISSN 2489-9003; 295, ISBN 978-951-39-8326-0
Link to publication:

For further information:
Hanna-Kaisa Lakka, +358 40 579 2045, hanna-kaisa.hk.lakka@jyu.fi

M.Sc. Hanna-Kaisa Lakka defends her doctoral dissertation in Ecology and Evolutionary Biology "Environmental changes is arctic freshwaters - The response of indicator species to global warming and acidification in the Arctic"  on Friday 23rd of October 2020 at 12:00 noon. Opponent Professor is Leopold Füreder (University of Innsbruck, Austria) and Custos is University Lecturer Emily Knott from the Ģ��ֱ��. The doctoral dissertation is held in English.

The audience can follow the dissertation online. Link to the Zoom Webinar (Zoom application or Google Chrome web browser recommended):