Advances in understanding marine ecosystems evolution in relation to volcanic activity

Hydrothermal vents, volcanism and marine ecosystems

Hydrothermal vents are considered as crucial areas where Earth will exchange heat and matter with the hydrosphere influencing ocean biogeochemical cycles at a global scale[1]. Newly formed surfaces or venting sources are known to be colonized by a succession of fauna, starting with microbial mats, grazers and the establishment of a suite of species whose recruitment is connected to variations in abiotic conditions and biotic interactions[2]. In addition, recent studies (e.g. the eruption of submarine volcano eruption off El Hierro Island, Canary Islands, on October 2011[3] ) have shown that submarine volcanic eruption may significantly impact the water column, leading to changes in the distribution and dynamics of pelagic fauna.  The submarine activity presently ongoing  off Mayotte provides an unique opportunity to study all these phenomena concentrated at one site.

[1] e.g. Tagliabue, A. et al. Hydrothermal contribution to the oceanic dissolved iron inventory, (2010), Nat. Geosci. 3, 252–256 (2010).

[2] Cuvelier et al, 2014 First insights into macro-and meiofaunal colonisation patterns on paired wood/slate substrata at Atlantic deep-sea hydrothermal vents, Deep-Sea Research I, 87, 70-81

[3] e.g. Ariza et al, (2014). The submarine volcano eruption off El Hierro Island: effects on the scattering migrant biota and the evolution of the pelagic communities. PloS one, 9(7), e102354

Understanding marine ecosystems evolution in relation to volcanic activity off Mayotte

The occurrence of the submarine eruption off Mayotte in 2018 has generated a remarkable diversity of scientific opportunities to understand the dynamics and coupling between lithospheric processes and the hydrosphere and biosphere compartments by providing an open window to the biodiversity and functioning of associated nascent marine ecosystems:

  1. What are the drivers for the appearance and development of life on a new volcanic edifice?
  2. What are the factors regulating the colonization / recolonization and larval dispersal processes depending on the faunistic and microbial diversity ?
  3. What are the fluxes of heat, chemicals and biomass to the overlying ocean associated with the eruptive and volcanic activity, and what are the driving processes involved?
  4. How does this eruption impact the living communities (from micro-organisms to larger fauna) in the benthic and pelagic compartments?
  5. What is the impact for the fishery and marine megafauna (such as marine mammals and turtles)?  Results here will help elaborate the specific management objectives of the Mayotte Marine National park.
Geoflamme cruise and ScinObs Project

From April 17th 2021 to May 05th 2021 with R/V Pourquoi pas? and ROV Victor, the Geoflamme cruise explored the seafloor three years after the 2018 eruption off Mayotte and performed in situ sampling (rock dredges, sediment cores, pore fluids, water) combined with high resolution mapping, mosaic, water column mapping and 3D reconstruction of volcanic structures to understand   the interactions between magmatism, tectonics and fluids circulation processes. The data of the Geoflamme cruise are presently under analysis. The results will help determine the locations of the autonomous, multi-disciplinary seafloor observatories that will be deployed in 2026 along with the submarine cabled, within the ScinObs project.