Simon Bahrndorff: Acclimation to moderate temperatures can have strong negative impacts on heat tolerance of arctic arthropods

Simon Bahrndorff: Acclimation to moderate temperatures can have strong negative impacts on heat tolerance of arctic arthropods

In this new post, Simon Bahrndorff of Aalborg University in Denmark presents his work ‘Acclimation to moderate temperatures can have strong negative impacts on heat tolerance of arctic arthropods. Simon discusses his research on the effects of prolonged exposure to moderate temperatures on terrestrial Arctic ectotherms and shares his thoughts on the importance of uncovering challenges and solutions for a changing world.

Narsarsuaq, Greenland (Credit: Simon Bahrndorff)
About the Paper

The Arctic is experiencing some of the fastest temperature changes observed on Earth. Most studies have focused on how Arctic ecthotherms, such as insects, mites, springtails and other arthropods have adapted to extreme low temperatures. Acute physiological upper thermal limits of terrestrial ectotherms from high latitudes often exceed the local air temperatures, suggesting that they may be able to cope with high and increasing temperatures, and results based on species from temperate areas suggest that Arctic species could even benefit from climate change. However, few studies have addressed how Arctic organisms cope with high and increasing temperatures.

In this study, a team of collaborators from Aalborg and Aarhus Universities in Denmark have addressed how Arctic terrestrial ectotherms cope with high and increasing temperatures. Surprisingly, we found that while the tested species in the current study can tolerate high temperatures for brief periods of time, exposure to moderate temperatures for a period between has strong negative effects on the heat tolerance of four of the five species. Based on this, we object to the established assumption that heat acclimation can always aid in rescuing populations that are exposed to temperatures close their tolerance limits. This approach would likely not be applicable to many high latitude terrestrial arthropod species in the face of ongoing and rapid warming in these parts of the world. 

Consequently, climate change leading to extended periods of mildly elevated temperatures may have strong negative effects on these species. We argue that this point is currently overlooked when assessing the ability of arthropods from Arctic and sub-Artic regions to cope with climate changes, as such predictions are typically based on acute heat tolerance estimates (and with the assumption of beneficial acclimation responses).

About the Research

To better understand how terrestrial ectotherms in the Arctic cope with high temperatures, the team set out to investigate how exposure to different temperatures for various lengths of time affects these organisms’ heat tolerance. We aimed to analyse whether acclimation to moderately high temperatures provided benefit or was detrimental in terms of heat tolerance for five species immediately after collection in Arctic (Svalbard) and sub-Arctic habitats (South Greenland). While it can be challenging to work under Arctic conditions–and thus get good estimates of species thermal tolerances–we benefitted from existing infrastructure in Narsarsuaq and Ny Ålesund, allowing us to carry out a range of controlled laboratory experiments. We enjoyed very nice sunny weather, as we had done during previous field campaigns in the Arctic during summer. Surprisingly, most of the species we worked with in Narsarsuaq were out during the warmest periods of the day.

Jesper Givskov Sørensen collecting springtails (Credit: Simon Bahrndorff)

Jesper Givskov Sørensen collecting springtails under cliffs (Credit: Simon Bahrndorff)

While our work contributes to a bigger picture on how polar organisms cope with high and increasing temperatures, it is also clear that there is a scarcity of studies addressing adaptation to high temperatures in the Arctic and Antarctic. The impact of climate change on arthropods species populations in Arctic and sub-Arctic regions is complex, and dependent on interactions between multiple biotic and abiotic factors, of which we we investigated just one factor. We urgently need more information on thermal plasticity and evolutionary adaptation in Arctic organisms. Such information may help us better understand thermal responses across species and will be instrumental in forecasting the impact of climate change on arthropods more broadly across polar regions.

About the Author
The author, Simon Bahrndorff, in Svalbard (Credit: Simon Bahrndorff)

I grew up surrounded by forests and fjords, which first triggered my interest in ecology. I have always had a deep passion for nature and understanding the interactions between species and with experience, I have developed a more mechanistic understanding of the ecological patterns I observed. My current work revolves around invertebrates and their adaptive responses to different abiotic and biotic factors, as well as understanding the underlying mechanisms explaining phenotypic differences across different temporal and spatial scales. It is clear that many ecosystems are challenged by different anthropogenic activities, as our recent study suggests. Regarding this, part of my research is also focused on solutions to reduce our environmental impact on ecosystems. I enjoy the possibilities that my work offers and that my research can uncover challenges as well as solutions for a changing world. I am looking forward to this year’s campaign in the Arctic with colleagues and students, and to meet with friends in the Arctic that have contributed to our work. This will hopefully bring us closer to a better understanding of thermal responses of organisms in the Arctic, and a mechanistic understanding of the ecological patterns observed in this unique environment.

Enjoy this blogpost? Read the research here.
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