Pågående og fullførte doktogradsprosjekter

PhD project of Christian Nilsson, supervisor: Mari Heggernes Eilertsen

Funding

WormFEST project, Research Council of Norway (Norges Forskningsråd, FRIPRO program)

Project description

The deep sea is generally a nutrient-poor environment, dependent on sinking organic matter produced at shallow depths. However, an exception to this can be found in chemosynthesis-based ecosystems (CBEs) such as organic falls, cold seeps, and hydrothermal vents. Here, microbes can fixate carbon through chemosynthesis, a process similar to photosynthesis, except it uses chemical energy instead of light energy. Some chemosynthetic microbes form symbiotic relationships with tube-worms, allowing them to form dense three-dimensional structures, much like how trees form the structure of a forest. These “worm-forests” may act as habitats, feeding-grounds, and nurseries for a wide range of animal groups. Therefore, CBEs are important sites where vibrant communities can flourish even in dark, deep waters.

While worm-forests at vents and seeps are well known from other ocean regions, those found in the Arctic remain largely uncharacterized. Therefore, my PhD project aims to address this knowledge gap through a baseline characterization of Arctic worm-forests in regard to their community-structure and functioning. This aim will be divided into sub-tasks of:

1. Identifying drivers behind the occurrence and structure of Arctic worm-forests.
2. Characterize the community composition and functional traits of worm forests across vents and seeps.
3. Reconstructing the food webs of these ecosystems.

Because of their specialized fauna, hydrothermal vent and cold seep communities are highly vulnerable to fragmentation from human disturbances and will therefore require informed conservation measures. By characterizing Arctic worm-forest communities this project will help in the identification of key environmental conditions and sensitive fauna, facilitating preservation of these unique ecosystems.
 

PhD project of Brenda Vazquez, supervisors: Mari Heggernes Eilertsen, Pedro Ribeiro, Runar Stokke and Ida Helene Steen.

Funding

Artsdatabanken Vent & Seep Fauna, EcoSafe Ridge Mining and DeepSeaQuence projects at the Department of Biological Sciences, UiB.

Project description

In the deep ocean, chemosynthesis-based ecosystems (CBEs) include hydrothermal vents, cold seeps, and organic falls where life relies on reduced inorganic chemicals (i.e., methane, sulfide, or hydrogen). Microbial communities use these chemicals to obtain energy and fixate carbon, representing the primary food source in these ecosystems. On the other hand, specialized fauna needs adaptations to overcome challenging physicochemical conditions and take advantage of the nutrient availability (i.e., symbiosis with microbes).

One of the most common animals inhabiting Arctic CBEs are snails in the family Rissoidae. Preliminary DNA barcoding data indicates that there are at least three genetically distinct but closely related species of rissoids in Arctic CBEs. While they are clearly specialized, these species appear to be able to inhabit a wide range of reducing conditions, from hot vents to decaying wood. Thus, my PhD project aims to study the distribution, genetic connectivity, and adaptations of rissoid gastropods in Arctic CBEs. I will combine three different approaches: 1) DNA barcoding and 2b-RAD sequencing, 2) biophysical modelling of larval dispersal and 3) integrated genome-centric metagenomics and fluorescence in situ hybridization (FISH)-confocal laser scanning microscopy. Given the potential impact of planned deep-sea mining activities on the AMOR, the project will contribute to the understanding of specialized fauna in the region, providing the baselines for Red List inclusion and further conservation planning in the AMOR.
 

PhD project of Chanakan Boonnawa, supervisors: Assoc. Prof. Eoghan P. Reeves and Prof. Ida H. Steen

Funding

Research Council of Norway FRINATEK project “HyPOD”, and the Thai Ministry of Higher Education, Science, Research, and Innovation

Project description

Abiotic production of organic carbon species in seafloor hydrothermal system has long been postulated. It has gained the community’s attention as it may be a reasonable supply source of prebiotic organic compounds leading to the emergence of life on early earth and other worlds. Apart from the ‘Fischer-Tropsch-type (FTT)’ synthesis (solid-phase catalyzed), an alternative pathway for abiotic organic carbons production is the mineral-free (homogeneous) sequential carbon reduction. Despite being more applicable to natural hydrothermal system, the latter is less studied.

In this project, I am aiming to (i) further develop our understanding of homogeneous (in the absence of solid-phase catalyzers) abiotic production of simple organic carbon compounds in hydrothermal conditions using detailed high temperature and pressure experimentation and (ii) use field data from natural fluid samples collected from a site of suspected abiotic synthesis to better constrain the geochemical settings in which abiotic synthesis can occur. During the project, 3 different sets of detailed experiments will be conducted in order to elucidate the following topics (i) methanol (CH3OH) and methane (CH4) production as a function of pH (ii) effects of H2S on hydrothermal single carbon reduction (iii) constraining the reactivity and fate of methanethiol (CH3SH) in seafloor hydrothermal conditions.
 
 

PhD project of Renee Hageman, supervisors: Steffen Leth Jørgensen and Bjarte Hannisdal

Microorganisms in the deep sea sedimentary biosphere live under severe energy limitation by residing under high pressure, low temperature, and low availability of organic matter. Therefore, deep sea sediments was long believed to be uninhabitable for live. More and more evidence shows that deep sea microorganisms are more likely to be active than dormant or dead despite their continuously limited metabolism. During the PhD project we aim to elucidate more of the activities of microorganism in deep sea sediments by using DNA and RNA combined with reactive transport modelling.

PhD project of Ingvild Aarrestad, supervisors: Andreas Beinlich, Desiree Roerdink, Oliver Plümper (University of Utrecht)

My project is focused on identifying, investigating, and quantifying feedback mechanisms in fluid-rock interactions. Silicate-silicate feedback mechanisms are explored by a systematic experimental approach using the serpentinization of olivine and pyroxene as a model system. Further, a silicate-sulfide system will be explored, investigating feedback mechanisms in tenor upgrading of sulfide ore deposits. The feedback mechanisms are quantified via kinetic modelling by extracting kinetic parameters from experimental results. Finally, experimental results will be linked to natural observations to constrain alteration reaction sequences and timescales.
 

PhD project of Emily Denny, supervisors: Håkon Dahle, Ida Helene Steen, Runar Stokke, Ruth-Anne Sandaa, Eoghan Reeves

Dramatic chemical gradients within deep sea hydrothermal vent systems provide means for growth of lithoautotrophic life through a diverse yet limited set of redox reactions. My bioinformatic / molecular ecology-focused PhD work aims to gain insights into the microbial food webs of the chemically variable vent systems discovered to date across the Arctic Mid-Ocean Ridge including primary production, organotophy, and viral signatures. I use metagenomic data analysis to investigate the functional diversity of primary producers in these systems and connect this information to the local geochemistry using energy landscape and microbial community modeling. I am interested in the metabolic hand-offs present within these food webs, as well as the possibility that different primary producer assemblages in vent systems may support different types of organotrophic life.

You can also read a bit more about Emily on the webpage of CBU.
 

PhD project of Trong Thuc Nguyen, supervisor: Runar Stokke and Ida Helene Steen

His Ph.D. research project focuses on the diversity of microbial communities at Arctic deep-sea hydrothermal vents and their potential biological products. The project will explore the metagenomics and metatranscriptomics data from the deep-sea microbiota to investigate the diversity of biosynthetic gene clusters (BGCs) and novel anti-microbial peptides (AMPs) among those microbial genomes. With -omic technologies, the goal is to investigate those metabolic interactions inside the deep-sea microbial communities and search for novel biological compounds that can be applied in biotechnology, and to infer potential ecological roles of such compounds.
 

PhD project of Hannah Babel, Steffen Jørgensen and Andreas Türke.

I am fascinated by the relationships between microbes and their host environments. This interest is what led me to my PhD project in geomicrobioloy. My project, titled "Into the Deep: Exploring microbial life and fluid-rock interactions in oceanic crust", aims to better understand the diversity and ecosystem role microbial communities have in the deep oceanic crust biosphere. I will be investigating the pioneering microbial community composition on freshly formed basalts, exploring the metabolic potential and diversity of the microbial communities from various oceanic crust sites, and identifying the role microbes have on basalt alteration rates using a series of experiments. I hope that my research will contribute to what little knowledge we have about the global impact of this massive biome and the mechanisms of life in the deep subsurface biosphere.
 

PhD project of Solveig Lie Onstad, supervisors: Rolf Birger Pedersen, Thibaut Barreyre, Malte Sommer

Funding

Norwegian Petroleum Directorate, K.G. Jebsen Centre for Deep Sea Research

Project description

In a world with an increasing population and a rising focus on renewable energy, metals are in demand as never before. The deep oceans hold a variety of mineral deposits and due to advancements in subsea technology, many countries are now exploring the feasibility of mining marine mineral resources on the seafloor. However, today there is no effective methods to detect seafloor massive sulfide (SMS) deposits or ferromanganese crust. The objectives of this PhD project will be to establish a new framework that leverages on combined imagery, acoustic and electro-magnetic datasets to enhance detection and characterization of deep-sea environments such as active and inactive hydrothermal systems (SMS deposits) and ferromanganese crust. 
 

PhD project of Stian Rolfsen Gilje, supervisors: Rolf Birger Pedersen, Cédric Hamelin

Funding: Norwegian Petroleum Directorate, K.G. Jebsen Centre for Deep Sea Research

My research focuses on hydrogenetic ferromanganese crust in the Norwegian-Greenland Sea. My work will help estimate the deep sea resource potential in Norwegian waters. Furthermore, I will use Fe-Mn crusts to elucidate paleoceanography of the deep ocean using a combination of isotopes and crustal chemistry. In addtion, these crusts provide information on element transport to the deep ocean in general.
 

PhD project of Linn Merethe Brekke Olsen, supervisors: Ingunn H. Thorseth, Håkon Dahle, Ingeborg Økland (Rådgivende biologer), Hans Peter Arp (NGI)

Plastic pollution and stability of mine tailings in the marine environment
 

PhD project of Anna Patova, supervisor: Hans Tore Rapp

My project aims to investigate the genetic diversity, structure, and connectivity of key habitat-forming sponges of the North Atlantic. The thesis focuses on species from the class Hexactinellida that formstructurally complex habitats and provide important services for the deep sea. We want to learn more about spatial patterns of genetic diversity across each species distribution range, asses the impact of variable fishing pressure on the population structure, and evaluate reproduction strategies in populations (asexual vs. sexual) on different scales and different distribution ranges. We use NGS methods (RADseq) to accomplish our goals.The generated data will deepen our understanding of genetic patterns in the deep-sea sponge grounds and we will learn more about how sustainable they are under human impact. The results will help to design conservation strategies and potential restoration activities of the grounds.

PhD project of Thomas Øfstegaard Viflot, supervisors: Eoghan Reeves, Ida Helene Steen, Thorsten Dittmar (University of Oldenburg) 

Funding: Research Council of Norway FRINATEK project “HyPOD”, and Department of Earth Science, University of Bergen 

Many modern seafloor hydrothermal systems evidently host a variety of life forms using different chemicals in the hydrothermal fluid as energy sources. Organic molecules essential for life here can originate from various sources, however, including heating of seawater containing dissolved organic matter (DOM), heating of organic-rich sediment, as well as abiotic synthesis from inorganic carbon (e.g. CO2). However, science has yet to fully comprehend the complexity of the diverse organic carbon production pathways in these systems. This project will aim to increase our understanding of how, which and where low molecular weight organic molecules are formed in these environments. Through experiments, I will simulate hydrothermal system conditions (high temperature and pressure) to investigate the low molecular weight organic molecules that may form from various sources (sediments, DOM and abiotic synthesis), and compare these results to field data with real hydrothermal fluid samples.