Hydrothermal vent ecosystems

Lead: Cindy Lee Van Dover, Duke University

Background

At the boundary between Earth’s divergent tectonic plates deep on the ocean floor forms a collection of volcanic ridges, rifts, fault zones and other geologic features known as the mid-ocean ridge. Along the ridge, seawater percolates into the crust through cracks and pores, it is heated by underlying magma and forced back to the surface through fissures in the rock as superheated jets laden with dissolved minerals. Fuelled by this cocktail of chemicals and extreme high pressure, dense mats of chemosynthetic bacteria and archaea thrive around the jets – commonly referred to as hydrothermal vents – forming the base of a food chain that supports a diverse community of giant tube worms, clams, snails and shrimp, themselves the food for passing predators. Relative to the majority of the deep sea, the areas around submarine hydrothermal vents are biologically more diverse and productive, with a high degree of specialisation and species endemism. Almost nothing is known about how these vent assemblages form, recruit, spread or maintain themselves.

The unique physical and chemical conditions found at deep-sea hydrothermal vents have led to the formation of mineral deposits that are becoming increasingly valuable and commercially exploitable. Mineral exploration companies have recently turned their attention to extraction of minerals from hydrothermal vent fields on the seafloor. The deep-sea mining industry, though still in its infancy, has the potential to inflict environmental impacts including sediment and chemical plumes from mining machinery affecting filter-feeding organisms, collapsing or reopening vents, gas hydrate release, or even underwater landslides. All of these impacts on such a fragile habitat and their broader ramifications into the deep-sea ecosystem are poorly understood, and are the subject of intense research so that control measures are implemented before exploitation commences.

This work is aimed at gaining a greater understanding of the physical and biological factors that shape hydrothermal vent communities on the northern Mid-Atlantic Ridge and to identify and quantify the risks at which these communities will be put by the practice of deep-sea mining. Identifying the risks and evaluating the effects of predicted impacts in the broader context of deep-sea ecosystem structure and function will entail the assessment of deep-sea connectivity pathways and dispersal capabilities of the organisms that depend upon them. Outputs of these activities will contribute to the development and assessment of spatial management options to safeguard such unique features, and include recommendations to stakeholders in industry, coastal nations and the International Seabed Authority (ISA) so that deep-sea mining can be regulated to achieve minimal environmental impact.

Objectives

  • To design spatial strategies to protect ecosystem structure, function and diversity at deep-sea hydrothermal vents.
  • To increase the capacity of coastal states and the ISA to sustainably manage the seabed environment, with a particular view to conserving biological diversity at deep-sea hydrothermal vents.

Approach

This work will involve the following steps:

  • Assessment of risks to biodiversity on the northern Mid-Atlantic Ridge through desk study and expert interviews. A review of risk assessment approaches before selection of the most appropriate approach is to be performed in consultation with an advisory group of experts. The chosen assessment approach is to be implemented at a specially-convened working group.
  • Development of a genetic connectivity model for hydrothermal vent invertebrates of the northern Mid-Atlantic Ridge using both genetic and hydrographic data.
  • Development followed by revision of multiple scientifically justified spatial management design options, including network design options spanning active and inactive vents, for the preservation of hydrothermal vent biodiversity in the light of potential deep-sea mining operations along the northern Mid-Atlantic Ridge.
  • Development a provision of a multi-authored Technical Report with final recommendations on the management of deep-sea mining activities targeted at the International Seabed Authority.
  • Publication and dissemination of scientific results in the peer-reviewed literature.

Application

Proposals for the designation of Areas of Particular Environmental Interest (APEI) around hydrothermal vent fields will be informed by the most appropriate risk assessment process and justified based on the most up-to-date scientific knowledge. The criteria for identifying and designating APEIs – the ISA’s own tool for excluding mining activities from areas of ecological significance – are compatible with criteria for identifying EBSAs. By driving the process of knowledge acquisition and contributing to the formulation of best mining practices around deep-sea hydrothermal vents, this work is at the centre of efforts to protect and preserve the unique biodiversity of deep-sea hydrothermal vents and in areas beyond national jurisdiction. Such outcomes represent the overall goal of both GOBI and the EBSA process.