The effects of climate change on antibiotic resistance development in commercially relevant fish species
Dr. Hassan Humeida, Dr. Jutta Wiese, GEOMAR
The oceans contribute 20% of animal protein to human diets worldwide and are even involved in meeting 50% of protein needs in poor countries. Climate change is impacting not only marine organisms but also the microbiomes that live on or within them. At the same time, the demand for food from the sea is increasing globally along with annual human population growth worldwide. Marine food sources are not infinite and their biodiversity is threatened by various factors, including human pollution and overfishing. The following Masters thesis performed within the WASCAL program seeks to screen for antibiotic resistant bacteria from commercially relevant fish species of the Cape Verde Islands. The impact of the stressors on fish health status will be determined by measuring anatomical, physiological and nutritional parameters, such as size, weight, organ intactness, among others. This Master’s thesis will be performed GEOMAR Helmholtz Centre for Ocean Research in Kiel.
The sponge resistome along the Schwentine
Dr. David K. Ngugi, GEOMAR
The river Schwentine is vital to Kiel's drinking water supply. Despite its natural reputation, the river's history is closely tied to Kiel's industrial development, including shipyards, hydroelectric power plants and sewage systems. Its animal inhabitants and associated microbes may reflect this human influence and are of concern as reservoirs of antimicrobial resistance (AMR).
We will study antimicrobial resistance in the Schwentine River using metagenomics and metatranscriptomics. Freshwater sponges are a model reservoir for AMR: they filter 95% of microbes in water, including antibiotic-resistant genes. The project aims to understand if freshwater sponges store ARGs that can be transferred to other microbes and passed up the food chain into drinking water. The MSc thesis will be carried out at GEOMAR Helmholtz Centre for Ocean Research in Kiel. Contact David Ngugi (dngugi@geomar.de) for more information.
3D reconstruction of a Poribacterium inside the marine sponge by FISH-CLEM
Shedding light on the genomic basis of the widespread poribacteria–sponge interactions
Dr. David K. Ngugi, GEOMAR
Sponges are among the most ancient animal phyla, having existed for over 600 million years. They thrive in various aquatic environments, where they share space with dense microbial communities. The microbial biomass in sponge tissue frequently exceeds several billion microbial cells per gram of animal tissue, significantly surpassing the microbial load in the surrounding seawater. Modern sequencing technologies show that the microbes in sponge tissue are very diverse and distinct from the water's. Some are sponge-specific, like 'Poribacteria'. This is a rare instance of a cosmopolitan symbiont in a sponge; most microbial symbionts in sponges tend to be host-specific. A global assessment of the genomic basis of the interaction between Poribacteria and sponges is lacking. The project aims to investigate the genetic diversity of "Poribacteria" in a global sponge microbiome project. The MSc thesis will be carried out at GEOMAR Helmholtz Centre for Ocean Research in Kiel. Contact David Ngugi (dngugi@geomar.de) for more information.
Halichondria panicea (greenish color on the left, yellow color on the right, photos A. Hethke)
Light-dependent changes in microalgae content in the microbiome of the Baltic Sea sponge Halichondria panicea, and does this has an effect on sponge survival during heat waves (working title)
Dr. Kristina Bayer, GEOMAR
This project follows up on the long-standing observation that the Baltic Sea sponge H. panicea occurs in two color morphs, ranging yellow to green. Green sponges are typically found in light-exposed areas while yellow color morphs are located under rocks and in crevices. Initial unpublished microscopical observations revealed noticeably more diatoms and microalgae in green than in yellow sponges. First, we could use Fluorescence Activated Cell Sorting (FACS) to allow the quantification of photosymbiont abundance in green and yellow sponge tissues during different seasons. Moreover, we will provide additional analysis based on 16S rRNA and 18S rRNA gene amplicon sequencing on yellow and green sponge individuals collected at different months of the year with added sampling effort during the summer peak. This effort will unveil the diversity of prokaryotic and eukaryotic microorganisms coinhabiting the sponge. It will further assess whether seasonal changes in the photosynthetic microorganisms correlates with potentially detrimental effects of the core microbiome and subsequently for the sponge holobiont. This effort will give new insides, if microalgae content changes during warm season might have an effect on sponge health and/ or disease especially during heat waves, which was observed in earlier studies.
This master thesis is part of a jointed DAAD proposal with partners from Portugal, which could provide also the possibility for exchange.
Interested candidates please contact Kristina Bayer (kbayer@geomar.de) or Ute Hentschel (uhentschel(at)geomar.de) for further information. The thesis needs to start in march 2025, latest.
