Five doctoral researchers in coastal biodiversity and carbon cycling

We are seeking five doctoral researchers to join the CoastClim Biodiversity PhD Collegium at Tvärminne Zoological Station, where the five complementary doctoral projects investigate how species composition, functional traits, interactions and community change regulate coastal carbon cycling. The doctoral researchers will be joined by two new postdoctoral researchers (see short description below and full application details on University of Helsinki open positions page).

Coastal ecosystems are changing rapidly, with consequences for biodiversity, carbon cycling and climate feedbacks. We address these issues in CoastClim, the Centre for Coastal Ecosystem and Climate Change Research. A central CoastClim hypothesis is that healthy and degraded ecosystems differ in how biodiversity regulates carbon production, storage, transformation and release. Yet the ecological mechanisms behind these differences remain poorly understood.

All five PhD projects share biodiversity and carbon cycling as their scientific core, while addressing complementary mechanisms across coastal habitats and spatial and temporal scales. Cross-cutting themes include environmental disturbance, multiple stressors, temporal community change, functional diversity and benthic–pelagic interactions. Field manipulations, laboratory experiments, long-term observations and biogeochemical measurements will build on CoastClim's interdisciplinary expertise and infrastructure at Tvärminne Zoological Station. Shared field and laboratory experiments will enable collaboration without compromising doctoral project independence. Together, the PhD collegium and postdocs will test CoastClim's healthy–degraded hypothesis by determining how biodiversity change alters carbon cycling and climate-relevant ecosystem processes.

Five interconnected PhD projects

1. Experimental biodiversity manipulation and coastal carbon cycling

Main supervisor: Alf Norkko
How does biodiversity loss affect carbon cycling and ecosystem metabolism in coastal marine habitats?

This predominantly field-based project will use SCUBA-based disturbance experiments to manipulate benthic biodiversity and compare carbon cycling in disturbed and undisturbed communities. Complementary long-term experiments with relatively intact sediment communities in laboratory mesocosms may test the effects of species composition, biomass and functional diversity.

Key response variables include carbon stocks, organic matter processing and ecosystem metabolism, measured through in situ benthic chamber incubations (production and respiration). Greenhouse gas (CO₂, CH₄) and VOC flux measurements may be incorporated through ongoing CoastClim collaborations.

Contrasting vegetated and non-vegetated habitats may be included; recolonization over 2–3 years is a possible extension. Applicants should have a strong foundation in benthic ecology, experimental design and quantitative analysis, as well as underwater fieldwork experience. Scientific diving qualifications or substantial diving experience are highly desirable.

2. Temporal biodiversity change, novel communities and carbon cycling

Main supervisor: Laura Kauppi
How do temporal changes in biodiversity, including the emergence of novel ecological communities, influence carbon cycling in coastal ecosystems?

This project will investigate how changes in species composition, biological interactions and community dominance, including introductions of non-native species, alter coastal carbon cycling.

Long-term ecological datasets will be combined with targeted field and laboratory studies to assess carbon stocks, organic matter processing and potentially benthic–pelagic exchange. Molecular biodiversity monitoring (e.g. ARMS/EMOBON) may be incorporated. Applicants should have strong statistical skills, experience handling ecological time series and an interest in community ecology. Experience in experimental benthic ecology or molecular biodiversity methods is an advantage.

3. Functional biodiversity and the mechanisms regulating benthic carbon cycling

Main supervisor: Anna Villnäs
Which functional characteristics of benthic biodiversity regulate carbon processing and biogeochemical functioning in coastal ecosystems?

This project will investigate how organism size, functional traits, resource use and species interactions influence organic matter processing and carbon dynamics, including links between benthic activity and microbial processes.

Field sampling, laboratory experiments and trait-based analyses will quantify, for example, the effects of bioturbation, bioirrigation and community composition on organic matter uptake, sediment biogeochemistry and carbon turnover. Benthic–pelagic coupling may be explored where relevant.

Ultimately, the research aims to identify how biodiversity influences the capacity of coastal sediments to process and retain carbon. Applicants should have a background in benthic ecology or sediment biogeochemistry, field and laboratory skills, strong statistical knowledge and the ability to collaborate across disciplines. Diving experience is an advantage.

4. Biodiversity, multiple stressors and coastal carbon dynamics

Main supervisor: Joanna Norkko
How do interacting environmental stressors modify the relationships between biodiversity, ecosystem functioning and carbon cycling?

This primarily laboratory-based project will test how warming, hypoxia and reoxygenation, separately and combined, affect coastal communities with contrasting biodiversity and disturbance histories.

Controlled incubations and mesocosms will quantify responses in ecosystem metabolism, carbon turnover and the production and consumption of greenhouse gases and, where feasible, VOCs.

Longer experiments with sediment communities may examine how species composition, biomass and functional diversity mediate responses to stress, including functional changes following hypoxia and reoxygenation. Applicants should have a background in experimental marine ecology or aquatic biogeochemistry, sound experimental-design and statistical skills, and an interest in laboratory incubations and gas-flux measurements. Experience with multiple-stressor experiments is an advantage.

5. Pelagic and microbial biodiversity in coastal carbon cycling

Main supervisor: Aleksandra Lewandowska
How do pelagic biodiversity and microbial communities influence carbon uptake, transformation and climate-relevant compounds?

This project will examine how phytoplankton and other microbial communities shape organic carbon dynamics and the production of climate-active compounds in coastal waters. A core component will involve field sampling and laboratory analyses linked to ongoing CoastClim monitoring, including the footprint of the atmospheric flux tower (ICOS station).

Where feasible, complementary incubations may explore benthic–pelagic exchange and links between pelagic biodiversity, sediment processes and air–water carbon fluxes.

Applicants should have a strong background in microalgal or microbial ecology, good laboratory and field-sampling skills, and proficiency in statistics and/or bioinformatics. Experience with coastal monitoring or oceanographic fieldwork is an advantage.

The doctoral researchers will be joined by two new postdoctoral researchers. These projects are shortly described below, and full application details can be found on University of Helsinki open positions page.

Postdoc 1. Coastal sediment microbial ecology and biogeochemistry (3 years)
The postdoctoral researcher will investigate how sediment microbial communities and biogeochemical processes mediate biodiversity–carbon relationships, including carbon mineralization, greenhouse gas dynamics (particularly CH₄) and potentially VOC production and degradation.

Applications are welcome from microbial ecologists and marine biogeochemists with relevant sediment expertise, strong quantitative and scientific writing skills, and a record of independent publication. Molecular methods, porewater analyses and incubation experiments are complementary strengths. The researcher is expected to develop an independent research line while collaborating across the PhD collegium.

Postdoc 2. Experimental marine ecology and biodiversity–ecosystem functioning (3 years)
The postdoctoral researcher will use field-based biodiversity manipulations to test how community structure and disturbance affect carbon cycling across coastal habitats, including experimental measurements of benthic ecosystem metabolism.

Proven SCUBA/scientific diving experience, sound experimental design, quantitative analysis and strong scientific writing are essential. Experience with benthic chamber or sediment experiments is an advantage. The researcher will develop an independent research line while contributing to shared field experiments and collaborating across the PhD collegium.

What we offer

The doctoral positions are based at Tvärminne Zoological Station on the southwestern coast of Finland. This is an opportunity to join the growing CoastClim consortium, with close collaboration between the University of Helsinki and Stockholm University. The five doctoral researcher positions are fully funded for four years, starting in early 2027. A trial period of six months will be applied. The succesful candidates must obtain the right to pursue a doctoral degree at the University of Helsinki within the trial period.

The funding for these positions is awarded by the Walter and Andrée de Nottbeck Foundation. The doctoral researchers are employed by the University of Helsinki and are paid 20% as salary and 80% as a personal grant (in total about 2400 euro per month, where tax is paid only on 20% of this). The University of Helsinki offers comprehensive services to its employees, including occupational health care.

How to apply

Applications must be submitted through the University of Helsinki's online recruitment system using the "Apply Now" button. Applicants currently employed by the University of Helsinki should submit their application through the SAP Fiori portal via "Employee login".

Please submit the following documents as a single PDF file in the field reserved for CV:

• A motivation letter (maximum two pages) describing your interest in the position and outlining relevant experience.
• Clearly state which position you are applying for.
• A curriculum vitae, including a list of publications (if applicable).
• Two letters of recommendation, including the referees' contact information.
  
  The use of AI in application preparation will not be evaluated favourably.
  
   Application deadline: 7 December 2026 at 23:59 (Finnish time)
  
  

More information

For further information about the positions, please contact: project planner Johanna Gammal, johanna.gammal@helsinki.fi
Support with the recruitment system can be obtained from University of Helsinki HR specialists at recruitment@helsinki.fi.

A diverse and equitable study and work culture is important to us. That is why we do our best to promote an inclusive university community. We encourage all qualified applicants from diverse backgrounds to apply for our positions.

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