Active hydrothermal vent ecosystems in the Indian Ocean are in need of protection

Abstract

Deep-sea hydrothermal vent fields are among the most pristine and remarkable ecosystems on Earth. They are fueled by microbial chemosynthesis, harbor unique life and can be sources of precipitated mineral deposits. As the global demand for mineral resources rises, vent fields have been investigated for polymetallic sulfides (PMS) and biological resources. The International Seabed Authority (ISA) has issued 7 contracts for PMS exploration, including 4 licenses for vent fields in the Indian Ocean. Here, we provide a summary of the available ecological knowledge of Indian vent communities and we assess their vulnerability, sensitivity, ecological and biological significance. We combine and apply scientific criteria for Vulnerable Marine Ecosystems (VMEs) by FAO, Particular Sensitive Sea Areas (PSSAs) by IMO, and Ecologically or Biologically Significant Areas (EBSAs) by CBD. Our scientific assessment shows that all active vent fields in the Indian Ocean appear to meet all scientific criteria for protection, and both the high degree of uniqueness and fragility of these ecosystems stand out.

Microbial ecosystem assessment and hydrogen oxidation potential of newly discovered vent systems from the Central and South-East Indian Ridge

“…Given the relative abundances of these bacterial and archaeal autotrophs in the specific habitats ( Supplementary Figure S1 ), the expected primary biomass production is generally higher in the actively venting environments compared to those currently missing hydrothermal activity and especially the sampled sediments. This microbial primary production serves as the basis for the rich fauna at active venting sites and thus contributed significantly to the demands for the protection of active hydrothermal vents (e.g., van der Most et al, 2023 ). However, the microbial mats, sampled from non-venting sites of different vent fields, with their noticeable high numbers of autotrophic Mariprofundales ( Table 4 ; Singer et al, 2011 ) suggest that the microbial potential for CO 2 -fixation and primary biomass production in non-venting habitats should not be neglected when assessing the possible ecological impacts of SMS mining.…”

“…This gap includes both the geological background and the microbial and macrofaunal ecosystem functions ( Amon et al, 2022 ). A recent review summarized and analyzed the insights (with respect to putative mining impacts) on IR ecosystems gained so far, but focused almost exclusively on the studies and descriptions of macrofaunal communities, which are known to comprise several endemic species contributing to the need of protection of these ecosystems ( van der Most et al, 2023 ). However, in active vent environments, microbes also fulfill essential ecosystem functions and services like primary production and detoxification of harmful compounds, but also represent a valuable genetic resource for biotechnological or even medical applications ( Orcutt et al, 2020 and references therein).…”