Project Details
Projekt
Phytoplankton microbiomes: A trait for adaptation and poleward range shift?
Subject Area
Oceanography
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 562107587
In the Southern Ocean (SO), diatoms play a crucial ecosystem role due to primary production and the support of food web structures. However, the success and resilience of Antarctic diatom populations cannot solely be attributed to their individual genetic traits, but rather to their close association and interaction with diverse bacterial communities, collectively known as diatom microbiomes. Diatom microbiomes perform vital functions including nutrient recycling, iron harvesting via bacterial siderophores or provision of bacteria-derived vitamins and other growth stimulating compounds. Given that diatom microbiomes under a given set of environmental conditions are rather stable, their functions can be considered a biological trait. One of the key consequences of ocean warming on diatoms is a poleward shift of their distribution. In the different SO regions, diatoms encounter distinct environmental regimes, many of which pose a survival challenge on phytoplankton. We hypothesize the functional differentiation and adaptation of algal microbiomes to be an important driver enabling ecotypic differentiation of diatoms in SO regions. In this proposal, we will characterize phytoplankton trait-based abilities from a microbiome perspective and explore the microbiome’s functional potential to foster coping strategies and adaptation of phytoplankton to new environmental regimes during poleward range shift across the Sub-Antarctic Zone. By combining our strengths and expertise in diatom-bacteria interactions, microbial community dynamics, ecological genomics and single-cell and meta-omics, we propose to explore the functional repertoire and adaptive capacity of diatom microbiomes across a SO latitudinal gradient. In work package 1, we will conceptually test whether microbiome taxa can be exchanged between two co-occurring diatom species, and if so, which taxa shuffle which functions. In work package 2, we will determine the intra- and interspecific functional variability of diatom microbiomes, generating knowledge on local adaptations of microbiome taxa and the potential buffering capacity against losses of taxa from the phycosphere. In WP2, to reveal diatom species-specific microbiomes and their functions, we will construct metagenome-assembled genomes (MAGs) from bulk phytoplankton samples obtained at latitudinal sampling stations and compare them to the composition on single diatom cells, as revealed by metabarcoding (i.e., rRNA gene sequencing). This will allow assignment of the barcodes to bacterial genomes. This will allow a large sampling size for single diatom cell metabarcoding analyses without stretching the budget for metagenomic sequencing. Together, these WPs will allow us to assess the capacity of the holobiome in terms of its native or recruited microbiome functional composition to render the relevant life traits to cope and persist in different SO zones.
DFG Programme
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