A quantitative model of chemosynthetic growth of Riftia pachyptila controlled by variable in situ physicochemical conditions

Hydrothermal communities –as hotspots of chemosynthetic primary productivity on the deep ocean seafloor –contribute significantly to organic carbon cycling at local and potentially regional scale. Yet multi-scale variability from source fluid proper-ties driven by volcanism to short-term tidal influence on the physico-chemical properties of vent habitats, complicate estimation of their carbon fixation potential. Riftia pachyptila is a biomass dominant colonizer of the unstable environment of East Pacific Rise (EPR) 9°50’ N. Efficiency in resource uptake from mixed fluids and regulated supply to endosymbionts allows its fast growth. Our objective was estimating growth potential of Riftia controlled by environmental variation through a quantitative model. Though simulated growth rates were lower than maxima, the patterns are con-sistent with post-eruption observations. Decreasing source temperature improved growth, in post-eruption conditions, and reduced it when both sub-seafloor mixing and geochemical evolution of fluid over time co-occur. Retroaction on growth improved carbon fixation. Short-term variability of habitat conditions are a pre-requisite for growth. Higher variability demonstrated higher carbon fixation rates. Narrower ranges would limit access to sufficient sulfide or oxygen. High environmental variability of temperature could partly compensate aging of source fluid, contrary to cooler conditions. Regular access to O2 at high variability maximized growth.

Promotor(s) & Supervisor: Nadine Le Bris

ISCED Categories

The highlighted icons, represent the fields of education (in compliance with ISCED Classification) engaged during this course/programme.

0511 - Biology", "0532 - Physical and chemical oceanography", "0588 - Scientific modelling