Biodiversity of deep-sea sponge microbiomes in the ecosystem context

• Main Author: Busch, Kathrin
• Format: Thesis
• Language: English
• Published: 2020
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/51667/; https://oceanrep.geomar.de/id/eprint/51667/1/Dissertation_Kathrin_Busch_Vollfassung.pdf; https://macau.uni-kiel.de/receive/macau_mods_00000940

The deep-sea is the largest habitat on Earth, but its biodiversity and ecosystem dynamics are still underexplored. Deep-sea sponge grounds (syn. aggregations, gardens) are sponge-dominated ecosystems that are found throughout the world´s oceans. They are considered vulnerable marine ecosystems (VMEs) and warrant protection against human intervention. Deep-sea sponge grounds are considered hotspots of diversity and function in the deep ocean. While a significant body of information has been accrued on shallow-water sponges, our understanding of deep-sea sponges and their associated microbiomes at the beginning of this PhD thesis was still very limited. This PhD thesis therefore aims to provide a first comprehensive overview on the diversity, evolution, biogeography, and ecology of deep-sea sponge microbiomes. The overarching aim was to assess whether the concepts obtained in shallow-water sponge microbiology would also hold in the deep-sea. In addition, novel themes such as biogeochemistry, physical oceanography, and trait-based approaches were integrated and further expand the existing theoretical framework in sponge microbiology. Sampling was conducted during 20 deep-sea expeditions, largely to sponge grounds of the North Atlantic in the context of the EU project “SponGES: Deep-sea sponge grounds ecosystems of the North Atlantic - an integrated approach towards their preservation and sustainable exploitation”. In total 1077 sponge-associated microbiomes were sampled along with 355 seawater microbiomes and 114 sediment microbiomes from 52 sponge ground locations. Microbial diversity was assessed by 16S rRNA gene amplicon sequencing and host taxonomy was determined by a combination of taxonomic and molecular markers. To this end, a state-of-the-art high-throughput 16S amplicon pipeline was established and corresponding metadata workflows were developed. The resulting data were analysed by six specific case studies (of which all were published) and one overarching meta-analysis (manuscript in preparation). The ...