PhD positions in hadal biogeochemistry & microbial ecology

PhD positions in hadal biogeochemistry & microbial ecology
The Danish Center for Hadal Research (HADAL) at the Department of Biology University of Southern Denmark invites applicants for 5 Ph.D. positions in deep-sea biogeochemistry and microbial ecology. The positions are fully funded for 3 years by the Danish National Research Foundation and The Independent Research Fund Denmark. The respective Ph.D. projects are expected to be initiated during the period from July to October 2026. HADALis a Center of Excellence that explores life and element cycling in the deepest oceanic realm. The Center was founded in 2020 engages about 35 students technicians and scientists and has a large international network of collaborators. We seek committed candidates that can work focused and independently but that flourish in an international team having a strong synergetic and multidisciplinary approach for solving important research challenges. The scientific approach is based on advanced theoretical and experimental studies but international deep-sea expeditions are critical for our scientific advances. Candidates for the positions should be prepared for several weeks long international voyages. The specific profiles for the 5 available Ph.D. positions are outlined below:

PhD A Importance of dark carbon fixation in the deep ocean. There is growing evidence that dark carbon fixation contributes to the sustenance of heterotrophic life at great depth. Using 14C and 13C incubation approaches the current project will quantify dark carbon fixation rates in deep ocean settings and explore how environmental parameters affect the process rates. These approaches are planned to be complemented by NanoSIMS and MAR-FISH to explore key players and processes responsible for dark carbon fixation. Furthermore the project will include genomic approaches to characterize the microbial communities responsible for dark carbon fixation at hadal depth. The focus will be on pelagic communities but aspects of benthic chemosynthesis could be included.
For further information please contact Ronnie N Glud or Beate Kraft.

PhD B Plastic pollution in the deepest regions of the global ocean. Hadal trenches act as depocenters for novel entities such as persistent organic pollutants heavy metals and plastics. Despite increasing awareness of marine plastic pollution the environmental fate and impact of micro- and nano-plastics in the deepest ocean remains largely unknown. This PhD project will investigate the distribution sources and characteristics of micro- and nano-plastics in hadal sediments. The work will combine deep-sea sediment sampling with advanced analytical approaches for particle detection and polymer identification including confocal and high-resolution imaging and spectroscopic analyses such as OPTIR and micro-Raman spectroscopy. The results will provide new insights into the transport deposition and long-term storage of plastics in the deepest parts of the global ocean. Relevant experience in (micro)spectroscopic analysis image analysis or environmental particle analysis will be an advantage.
For further information please contact Elvis Genbo Xu or Ronnie N Glud.

PhD C Importance of virus for deep sea microbial performance. This project will focus on exploring the role of benthic viruses in elemental cycling at different spatial and temporal scales. There will be emphasis on the distribution and composition of free viral communities and prophages and the importance of phage-encoded auxiliary metabolic genes (AMGs) for viral and host performance. Further spatial and temporal successions in viral communities will be investigated in response to changes in environmental conditions and prokaryote community composition. The work will include collection and analysis of large metagenomic and genomic datasets virus and host isolation cultivation and characterization and molecular approaches to quantify gene distribution and expression (e.g. Real-Time PCR and transcriptomics). Candidates with a solid background in bioinformatics and experimental work with viruses are preferred. The viral ecology group in the HADAL center is based at Marine Biological Section (MBS) in Helsingør and most of the work is expected to be carried out at MBS. *
For further information please contact Mathias Middelboe or Ronnie N Glud.

PhD D - Effect of hydrostatic pressure on microbial performance. Marine microbes on sinking particles experience rapidly increasing pressure during their descent this is expected to influence fundamental cellular processes such as protein nucleic acid and lipid synthesis. The PhD student will investigate how hydrostatic pressure affects microbial activity and cellular functioning. The project will quantify activity at the single-cell level explore how pressure alters cellular functioning across specific microbial populations and assess phenotypic heterogeneity within populations. Experiments will combine high-pressure incubations of cultivated microbes and natural hadal communities with click-chemistry-based microscopy techniques. Prior experience with these relevant experimental approaches such as BONCAT are preferred.
For further information please contact Beate Kraft or Peter Stief.

PhD E - Linkage between activity and characteristics of membrane lipids of microbes. Degradation of organic carbon in deep sea sediments is critical for marine carbon cycling and climate regulation but difficult to quantify. This project will investigate the distribution of microbial membrane lipids across diverse deep-sea environments and explore how they can be used as proxies for benthic degradation activity. The work will combine lipid biomarker analyses with laboratory incubation experiments at controlled conditions. More specifically the experiments will systematically quantify how hydrostatic pressure temperature substrate- nutrient- and oxygen availability affect lipid characteristics. The insight will be used to assess global deep sea carbon turnover in the past and presently. Experience in lipid biomarker analysis microbial cultivation statistical modelling or machine learning is an advantage.
For further information please contact Wenjie Xiao or Ronnie N. Glud.

If you are interested in one (or more) of these positions please provide a motivated application that outlines your research vision the expertise and competence that you could bring to HADAL. We encourage you to include relevant references. We offer an opportunity to join a highly motivated international team of researchers fascinated by biochemistry and microbiology in the deepest part of the global ocean. Application deadline: 4 May 2026 23:59 and applications will be assessed by an expert assessor/committee. Shortlisting may be used in the assessment process. Incomplete applications and applications received after the deadline will neither be considered nor evaluated. This also applies to reference letters. Applicants will be informed of their assessment by the university.
General information about the position and the hadal center can be directed to Ronnie N Glud

E-mail list of contact people:
Beate Kraft ()
Elvis Genbo Xu ()
Mathias Middelboe ()
Peter Stief ()
Ronnie N Glud ()
Wenjie Xiao ()

About the Department of Biology
The Department of Biology(approximately 200 employees) conducts a wide range of research within the broad and diverse field of biology. Our research is organized in 5 research groups; focusing on more specific but still diverse disciplines and biological focus areas.

About Nordcee
At Nordcee six key research areas are explored Microbes and Element cycles; Deep-sea research Co-evolution of Life and Earth Oxygen Greenhouse gases and climate Sustainability and biotechnology: How microorganisms interact with their environment with a particular focus on how microbes influence the biogeochemical cycling of elements even in the deepest places on Earth the abyssal plains and hadal trenches; How life and Earth co-evolved over billions of years and how microbial life gave rise to oxygen creating beneficial conditions for the emergence of complex lifeforms; How microbes in the Anthropocene act as sinks or sources of various greenhouse gases. Finally how to harness microbial microorganisms for sustainable technologies of the future with geo- and bio-engineering strategies.

Conditions of employment
Appointment as a PhD fellow is a 3-year salaried position.
Employment of a PhD fellow can only happen after the PhD School has approved the candidate for admission.

Employment as a PhD fellow is governed by the collective agreement between the Ministry of Finance and the Danish Confederation of Professional Associations for academics in the state with the associated circular on the job structure for academic staff at Danish universities and the provisions for PhD fellows as described herein as well as the Protocol on PhD fellows signed by the Danish Ministry of Finance and the Danish Confederation of Professional Associations (AC).
Further information about salary and conditions of employment.

The person employed in the position may based on a specific individual managerial assessment be exempted from time registration also known as a self-organizer.

Application salary etc.
Appointment as a PhD Research Fellow is for three years. Employment stops automatically at the end of the period.(the 53 programme).

Further information about the PhD programme at the Faculty of Science can be found at thehomepage of the University wishes our staff to reflect the diversity of society and thus welcomes applications from all qualified candidates regardless of personal background.

Application must be in English and made in the form of a Declaration of Interest including the following:

• A letter stating your specific interest motivation and qualifications for the project in question (max. two pages) .
• Detailed CV including personal contact information anddate entries
• Copies of diplomas Bachelor as well as Masters degree including transcript of notes/grades.
• The names and complete contact details (phone numbers and e-mail) of at least two referees details for at least 2 referees who can vouch for your skills.

Shortlisting may be used in the assessment process. Please note that only shortlisted applicants will receive an assessment. Read about shortlisting at SDU.Incomplete applications and applications received after the deadline will neither be considered nor also applies to reference letters.

Applications will be assessed by an expert assessor/committee. Applicants will be informed of their assessment by the university. Applications will be assessed by an assessment committee and the shortlisted applicants will receive the part of the evaluation that concerns them. The committee may request additional information and if so it is the responsibility of the applicants to provide the necessary material.

Interviews and tests may be part of the overall evaluation.

Applications should be sent electronically via the link Apply now. The faculty expects applicants to read the information How to apply for a position at SDU before applying. Please note that the application documents should be in pdf-format and attached as three documents: motivation letter CV and the remaining documents.
If you experience technical problems please contact .

To qualify for the position as PhD fellow you must have obtained a masters degree (equivalent to a Danish masters degree) by the enrollment/employment date.

We recommend that as an international applicant you take the time to visitWork in Denmarkwhere you will find information and facts about moving to working and living in Denmark as well asthe International Staff Office at SDU.

About SDU
The University of Southern Denmark was established to create value for and with society. Whether our contributions come in the form of excellent research innovative solutions education or learning we must make a positive difference to society and contribute to a sustainable future. We do this by cultivating talents and creating the best environments for research and learning. It is therefore crucial that SDU retains develops and recruits talent. At the same time we need to ensure consistently high quality in all our activities and we can only do that with the right people. The Universitys researchers lecturers students managers and technical/administrative staff are the foundation of our success.