Extremeophiles and Extreme Environments

Microbial Eukaryotic Predation Pressure And Biomass At Deep-sea hydrothermal Vents: Implications For Deep-sea Carbon Cycling

By Keith Cowing
Status Report
biorxiv.org
August 18, 2023
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Microbial Eukaryotic Predation Pressure And Biomass At Deep-sea hydrothermal Vents: Implications For Deep-sea Carbon Cycling
Microeukaryotic cells captured with epifluorescence (DAPI filter) from FLP uptake experiments conducted in this study. All images are derived from shipboard experiments and scale bars are located within each panel. (a-c) Eukaryotic cells from grazing experiments conducted at vent site X-18. The cell in panel (a) contained a consumed FLP cell. Imaged cells from (d) Mustard Stand, (e) Shrimpocalypse, and (f) the plume at Von Damm. Two FLP cells are imaged inside the eukaryotic cell in (f). — biorxiv.org
biorxiv.org

Deep-sea hydrothermal vent geochemistry shapes the foundation of the microbial food web by fueling chemolithoautotrophic microbial activity. Microbial eukaryotes (or protists) play a critical role in hydrothermal vent food webs as consumers, hosts of symbiotic bacteria, and as a nutritional source to higher trophic levels.

We measured cell abundances and predation pressures of vent-associated microbial eukaryotes in low temperature diffuse hydrothermal fluids at the Von Damm and Piccard vent fields along the Mid-Cayman Rise in the Western Caribbean Sea. We present findings from experiments performed under in situ pressure that show higher cell abundances and grazing rates compared to those done at 1 atmosphere (shipboard ambient pressure); this trend was attributed to the impact of depressurization on cell integrity.

A relationship between protistan grazing rate, prey cell abundance, and temperature of end member hydrothermal vent fluid was observed at both vent fields, regardless of experimental approach. The quantification of protistan biomass and grazing pressure shows that hydrothermally-fueled microbial food webs play a significant role in the broader deep-sea carbon budget by contributing to local carbon export and supply of nutrient resources to the deep ocean.

https://doi.org/10.1101/2023.08.11.552852

https://www.biorxiv.org/content/10.1101/2023.08.11.552852v1, biorxiv.org

Astrobiology

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) πŸ––πŸ»