Applications are invited for a PhD fellowship/scholarship at Graduate School of Natural Sciences, Aarhus University, Denmark, within the Biology programme. The position is available from February 2026 or later.

Title:
Shifting strategies: The role of strict autotrophic and mixotrophic algae in primary production and carbon cycling across Arctic coastal salinity gradients

Research area and project description:
We invite applications for a 3-year PhD position in Arctic primary production at the Department of Biology at Aarhus University (AU). The position is available from 1 February 2026 or later.

The project is part of the Center for Ice-Free Arctic Research (CIFAR), a new Danish Research Center of Excellence funded by the Danish National Research Foundation. CIFAR’s research programme addresses how freshening from melting land ice and sea ice on Arctic coastal waters will transform the structure and functioning of Arctic marine ecosystems. This PhD project contributes to CIFAR’s focus area on how loss of land ice and sea ice affects primary production, community composition and food web structure in Arctic coastal waters. You can find more about CIFAR here: bio.au.dk/forskning/forskningscentre/cifar

This PhD project aims to investigate the emerging ecological role of mixotrophic phytoplankton in a future Arctic Ocean, where freshening from melting ice caps and sea ice is transforming the structure and functioning of Arctic estuarine and coastal ecosystems. Following the lower salinity and decrease in nutrient availability, the project explores how the balance may shift from traditional autotrophic production to a regime dominated by mixotrophic algae. Through a combination of high-resolution field studies in northeast Greenland and controlled laboratory experiments, the project will quantify the contributions of autotrophic and mixotrophic phytoplankton to primary production and identify the environmental drivers—salinity, nutrients, light, and pH—that trigger shifts between metabolic strategies.

The project will test the hypothesis that mixotrophs, though historically underrepresented in Arctic research, already play a critical role in marine productivity and are likely to become increasingly dominant as Arctic surface waters become more stratified and oligotrophic. Data generated will feed into ecosystem models predicting carbon flow, nutrient recycling, and microbial food web dynamics in Arctic estuarine and coastal ecosystems.

For technical reasons, you must upload a project description. When - as here - you apply for a specific project, please simply copy the project description above, and upload it as a PDF in the application. If you wish to, you can indicate an URL where further information can be found.

Qualifications and specific competences:
Applicants must have a relevant master’s degree in biology, oceanography, or similar subjects, and ideally have field experience, data analysis and programming skills (e.g., R, Python, Matlab, etc). We seek candidates that are team players who can play active scientific and social roles in a diverse and international lab setting. Strong oral and written communication skills are mandatory. The successful candidate is expected to participate actively in field campaigns in Greenland in August 2026 and April 2027.

Place of employment and place of work:
The place of employment is Aarhus University, and the place of work is Department of Biology, Ole Worms Alle 1, 8000 Aarhus C., Denmark. 

Contacts:
Applicants seeking further information for this project are invited to contact:
Assoc. Prof. Brian Sorrell, brian.sorrell@bio.au.dk

Prof. Tenna Riis, tenna.riis@bio.au.dk

Research Scientist Dorte Haubjerg Søgaard, doso@natur.gl

Associate Professor Lars Chresten Lund-Hansen, lund-hansen@bio.au.dk

How to apply:

For information about application requirements and mandatory attachments, please see the Application guide. Please read the Application guide thoroughly before applying.

When ready to apply, go to https://phd.nat.au.dk/for-applicants/apply-here/ (Note, the online application system opens 1 June 2025)

1. Choose August 2025 Call with deadline 1 November 2025 at 23:59 CEST.
2. You will be directed to the call and must choose the programme “Biology”.
3. In the boxed named “Study”: In the dropdown menu, please choose: “Shifting strategies: The role of strict autotrophic and mixotrophic algae in primary production and carbon cycling across Arctic coastal salinity gradients (Ssrsam)”

Please note:

• The programme committee may request further information or invite the applicant to attend an interview.

At the Faculty of Natural Science at Aarhus University, we strive to support our scientific staff in their career development. We focus on competency development and career clarification and want to make your opportunities transparent. On our website, you can find information on all types of scientific positions, as well as the entry criteria we use when assessing candidates. You can also read more about how we can assist you in your career planning and development.

Aarhus University’s ambition is to be an attractive and inspiring workplace for all and to foster a culture in which each individual has opportunities to thrive, achieve and develop. We view equality and diversity as assets, and we welcome all applicants. All interested candidates are encouraged to apply, regardless of their personal background.