How to map the resilience of hydrothermal vent fields: a tutorial. Verson 1.

Abstract

One of the targets for commercial mining is the Seafloor Massive Sulfides (SMSs) deposits formed around hydrothermal vents, which is a highly attractive source of copper, zinc, lead, gold and silver ores (Hoagland 2010, Herzig 1999, Binns and Scott 1993, Halbach et al. 1989). Hydrothermal vents host chemosynthetic communities as well as metal rich ores. The chemosynthetic communities consist of many endemic invertebrate species specifically adapted to the vent environment via microbial chemoautotrophic primary production (Van Dover 2010). These species have provided new scientific insights into the mechanisms by which organisms adopt to the extreme environment (Jannasch and Wirsen 1979). Furthermore, as reviewed by Le et al. (2016), ecological function and services of these communities range from providing habitat and refuge for other species including non-endemic species (Levin et al. 2016, Govenar 2010), playing a key role in global carbon, sulfur and heavy metals cycling (Jeanthon, 2000, D'Arcy and Amend 2013) and offering new biomolecules that could contribute to industrial development (Terpe et al. 2013, Mahon et al. 2015). Mining of seafloor massive sulfide deposits potentially changes the physico-chemical environment of a vent community through the loss of sulfide habitat, degradation of sulfide habitat quality, modification of fluid flux regimes and exposure of surrounding seafloor habitats (including non-sulfide habitats) to sedimentation and heavy metal deposition (International Seabed Authority 2007, Van Dover 2014). This will directly affect the ecological community by removing and reclaiming organisms, reducing the amount of habitable substrate and changing resource supply. Physico-chemical models and organism distribution data have been integrated to estimate the potential area of sedimentation (Coffey Natural Systems 2008b). However, after the instantaneous effects of a disturbance, the ecological community will reach a new equilibrium state within the disturbed environment (Ives and Carpenter 2007). Hence, potential impacts of artificial disturbances, including how they may cause extinction and modify community structure at different spatial scales (local, regional and global), and decrease diversity at different biological levels (genetic, species and phylogenetic), will be understood by considering both direct impacts of mining activities and subsequent ecological responses. Environmental impact assessments (EIAs) that lack this point of view might severely underestimate the potential risks of anthropological activities.