Høringssvar fra Arunima Sen (Nord University)

Dato: 12.04.2021

As a member of the Faculty of Biosciences and Aquaculture and Nord University (Bodø), I would like to express my interest and present some suggestions for the impact assessment programme for the mineral extraction activities on the Norwegian continental slope. I have studied the spatio-temporal dynamics of deep-sea hydrothermal vent communities (both active and inactive areas) for the purpose of studying natural changes in order to assess impact of deep-sea mining of polymetallic sulfides. At the time, my research was aimed at aiding policy and management of the first proposed hydrothermal vent mining activities by Nautilus Minerals, however, this particular mining activity has subsequently been indefinitely postponed.

At hydrothermal vents, in situ physico-chemical conditions determine distributions and presence of faunal species, and fluid geochemistry is itself determined by underlying geological processes. Local topography, microbial communities (on and below the seafloor), diffusion processes, etc. make vent systems extremely heterogeneous with respect to local conditions, which change across very small spatial scales. Combining in situ physico-chemical measurements with faunal distribution patterns is therefore important to understand relationships between local biota and the unique and specific environment of hydrothermal vents.

Therefore, one suggestion I would like to propose is coupling faunal mapping with in situ geochemical measurements, i.e., mapping both fauna and physico-chemical conditions. This applies to inactive or peripheral locations as well, since even seemingly inactive sites could nonetheless have small amounts of fluid flow and the dissolved sulfide or metals in them that would affect the presence or absence of various species. In fact at peripheral or inactive sites, in situ chemical measurements are particularly important since the low concentrations (that are nonetheless critical to the biology) can be difficult to measure ex situ, since oxidation and loss of chemicals can occur as samples are brought to the surface. Vent sites in the Norwegian Sea are often sedimented which further lends complexity to fluid release and also make them optimal for the use of in situ chemical sensors, yet till date, such instruments have not been used at Norwegian vents.

Furthermore, repeating such combined mapping efforts allows for detecting natural rates of changes and species turnover, including how such changes are linked to changing fluid flow regimes. Such monitoring activities would provide an excellent base for assessing natural changes and therefore, estimating how they would be affected by anthropogenic activity, or even approximating recovery trajectories.

It is important that a number of sites be set up for such type of monitoring activity, for different kinds of areas (black smokers, other active areas, inactive and background, peripheral sites etc.). Observatories such as the one proposed at Fåvne will provide plenty of data on change as well, but it will be limited to one location. Given the heterogeneity of individual vent sites, such data would only account for one aspect or microhabitat within the larger vent landscape.

The establishment of monitoring stations to methodically document changes has been used in deep-sea systems and has even revealed unexpected results regarding the rate of change and resilience of habitats including vents. It has even been used very successfully to evaluate and follow, over time, the impact of catastrophic events in deep waters, such as the effect of the Deepwater Horizon oil spill on deep-sea corals. Therefore I believe such activities will be valuable additions to the proposed impact assessment programme.

Thank you,


Arunima Sen
Nord University