GEOMAR Helmholtz Centre for Ocean Research Kiel is a foundation under public law jointly financed by the Federal Republic of Germany (90%) and the State of Schleswig-Holstein (10%). It is one of the internationally leading institutions in the field of marine research.
Through our research and our commitment to the transfer of knowledge and technology, we contribute significantly to the preservation of the function and protection of the ocean for future generations.
The Harter Lab is part the Research Unit “Experimental Ecology” within the Research Division “Marine Ecology” (RD3). The overarching goal of our combined research efforts is to understand the biological mechanisms that determine the resilience of marine organisms to anthropogenic environmental change, such as global warming, ocean acidification, eutrophication and pollution.
Background | As global ocean temperatures increase, so does the body temperature of all cold-blooded fishes, a group that represent half of all vertebrate species. The challenge is two-fold: warmer water contains less oxygen while warmer body temperatures increase oxygen demand. Overcoming this fundamental imbalance between oxygen supply and demand may be the key for fish species to survive in a changing world. The bulk of oxygen transport from the environment to the tissues is carried out by haemoglobin within red blood cells. Emerging evidence indicates that red blood cells are not simply a vessel for haemoglobin, but actively participate in the regulation of cardiovascular gas transport: i) by modulating their intracellular microenvironment and the characteristics of haemoglobin; ii) by sensing the oxygen and acid-base conditions in the microvasculature; and iii) by releasing signalling molecules into the blood that regulate the local blood supply and the oxygen consumption of the tissues. The cellular and molecular mechanisms by which red blood cells sense their environment, maintain cellular homeostasis and interact with other cell types are still poorly understood. In addition, how climate change affects red blood cell function and their ability to regulate cardiovascular gas transport in fishes, remains entirely unknown.
Objective | To characterise cellular mechanisms of phenotypic plasticity, by which fish red blood cells regulate the function of respiratory proteins in response to metabolic and environmental stress.
Model system | Populations of Atlantic cod (Gadus morhua) from the Baltic, Atlantic and Arctic Oceans are experiencing vastly different rates of environmental change and thus, present a unique opportunity to study local adaptations and phenotypic plasticity at the level of the red blood cells. This species is of great commercial interest for fisheries and aquaculture and maintains a pivotal ecological role as a top predator.
Outcomes | This work will improve our fundamental understanding of how single cells respond to external stressors, regulate their intracellular microenvironment and contribute to systemic homeostasis. Results may unveil novel therapeutic targets that improve health outcomes in human medicine, and the knowledge will be critical to understand, predict and mitigate the impacts of climate change on fishes, aquatic ecosystems and human economic activities that depend on them (aquaculture, fisheries, tourism).
The research unit “Experimental Ecology” in the research division 3: “Marine Ecology” is offering the following position, starting as early as April 1st 2025. This position offers the possibility to attain a doctoral degree in natural sciences.
Job Description
The successful candidate will investigate the phenotypic plasticity of red blood cell function in Atlantic cod by conducting in vivo acclimation experiments to: i) warming; ii) hypoxia; and iii) hypercapnia/ocean acidification. Red blood cell function will be assessed before and after the acclimation period, using: i) molecular techniques (transcriptomincs, western blots); ii) microscopy techniques (immunocytochemitry with super-resolution microscopy and intracellular pH regulation by live-cell imaging); and iii) biochemical assays (haemoglobin-oxygen binding characteristics, cellular metabolic rates, enzyme activities and membrane properties). Then, to establish a functional link between red blood cell physiology and organismal performance, the metabolic rate of acclimated fish will be measured by respirometry and after aerobic challenges: i) warming to determine the critical thermal maximum (CTmax); ii) exercise in a swim tunnel to determine the maximal swim speed (Ucrit); and iii) intermittent hypoxia to determine the critical PO2 (Pcrit) that is required to maintain routine aerobic metabolism. Therefore, this project combines cutting-edge microscopy techniques for super-resolution and live-cell imaging, with a variety of cell and molecular lab techniques and whole animal metabolic measurements. In addition, the successful candidate will participate in ocean-going expeditions on GEOMAR/AWI vessels in the Baltic, Atlantic and Arctic, to capture Atlantic cod populations in the wild and will help maintain animals at the GEOMAR aquatic facilities. Candidates are expected to be fluent in English, have excellent communication skills and a desire to work with others in a diverse international team. Finally, PhD candidates will have the opportunity to mentor graduate and undergraduate students and participate in teaching and outreach activities at the GEOMAR, AWI and the University of Kiel. Required qualifications:
MSc. in comparative physiology, marine biology, or related fields
A record of peer-reviewed publications commensurate with career stage, and/or previous presentations at scientific conferences
Strong background in laboratory work including basic techniques in molecular biology and/or biochemistry
Fluency in English (both written and spoken)
Willingness to travel and ability to participate in sea-going expeditions
Preferred qualifications:
Experience with the capture, husbandry and handling of fish
Experience with aquatic respirometry and swim tunnel experiments
Experience with microrespirometry (e.g., Oroboros system) and mitochondrial assays
Experience with biochemical assays for enzyme activity
Experience with transcriptomics analysis At a workplace, directly on the Kiel Fjord with many leisure and recreational opportunities, we offer:
Good conditions for work-life balance: We offer, among other things, the possibility of mobile working and individual working time arrangements, vacation courses for the children of our employees, and good support in finding a place in a daycare center at the Kiel site
Support services for professional and personal life situations
An exciting work environment with the opportunity to provide important impetus for the development of sustainable solutions
Exciting topics in an international environment
Work in the field of marine and climate research, a forward-looking area with social significance
30 vacation days + additional time off at Christmas Eve and New Year's Eve
Company pension plan and capital-forming benefits
This 3-year PhD position is funded through an Emmy Noether grant from the German Research Foundation (DFG) as part of a larger, 6-year project. The salary will depend on the candidate’s qualifications and may be up to class E13 TVöD-Bund of the German tariff for public employees. This is a 75% position with flexible work hours that cannot be split.
GEOMAR Helmholtz Centre for Ocean Research Kiel seeks to increase the proportion of female scientists and explicitly encourages qualified female academics to apply. GEOMAR is an equal opportunity employer and encourages scientists with disabilities to apply. Qualified disabled applicants will receive preference in the application process.