Mechanistic modelling of the ecosystem function of deep-sea sponge microbiomes

• Applicant: Dr. Kathrin Busch
• Subject Area: Oceanography
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527686350

Deep-sea sponge grounds occur world-wide, and represent important biodiversity hotspots, including nurseries of commercially important fish, in the deep ocean. Due to their highly efficient filtering capacity, sponges play an important role in the major biogeochemical cycles, including the carbon and nitrogen cycle. The conversion of elements happens inside the sponge tissue, with the help of the highly diverse and metabolically active sponge microbiome. To understand deep-sea sponge ground ecosystems we need to understand how interactions between individual microbial cells correspond to the dynamics of the larger ecosystem. My project goal is to evaluate how dynamic metabolic interactions between deep-sea sponge microbes are related to larger nutrient cycles in a natural and disturbed setting. I will use the deep-sea glass sponge Vazella pourtalesii as a model system to answer my study questions. In particular I aim to: (I) Understand the natural dynamics - What are the mechanisms behind the plastic role of the V. pourtalesii sponge ground functioning as ammonium source or sink? (II) Understand the impact of shifts in environmental factors - How might shifts in environmental conditions (altered oxygen and nutrient conditions) impact microbial metabolic cycling and microbial interactions of the glass sponge V. pourtalesii? (III) Understand the impact of changes in microbial community composition on the larger ecosystem - How do shifts in the microbiome of V. pourtalesii translate into modifications in ecosystem function? What happens if certain microbes are excluded or a subset of the community is stochastically assembled? (IV) Synthesise and upscale the results - Can I scale up my V. pourtalesii modelling framework across large spatial scales and times? Taken together, my proposed project will create new conceptual links between symbioses and biogeochemical research for a relevant marine study system (deep-sea sponge grounds). This will be done with the help of metagenomic analyses and innovative modelling approaches.

• DFG Programme: WBP Fellowship
• International Connection: Australia, USA
• Hosts: Professorin Naomi Levine; Professor Dr. Torsten Thomas