Seafloor massive sulfide deposits support unique megafaunal assemblages: Implications for seabed mining and conservation

Abstract

Mining of seafloor massive sulfides (SMS) is imminent, but the ecology of assemblages at SMS deposits is poorly known. Proposed conservation strategies include protected areas to preserve biodiversity at risk from mining impacts. Determining site suitability requires biological characterisation of the mine site and protected area(s). Video survey of a proposed mine site and protected area off New Zealand revealed unique megafaunal assemblages at the mine site. Significant relationships were identified between assemblage structure and environmental conditions, including hydrothermal features. Unique assemblages occurred at both active and inactive chimneys and are particularly at risk from mining-related impacts. The occurrence of unique assemblages at the mine site suggests that the proposed protected area is insufficient alone and should instead form part of a network. These results provide support for including hydrothermally active and inactive features within networks of protected areas and emphasise the need for quantitative survey data of proposed sites.

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…Initially the disturbance was limited to harvesting and manipulation by scientific researchers, but as extraction of vent deposits rich in copper, zinc, silver, and gold becomes economically feasible, mining efforts are being initiated and debate over their regulation is intensifying (Hoagland et al, 2010;Van Dover, 2011;Gobin and da Fonseca, 2014;Mengerink et al, 2014). Mining can result in the destruction of vent communities and alteration of vent habitat, potentially impacting persistence and species diversity by causing further fragmentation in an already fragmented system (Boschen et al, 2016). Metacommunity models are ideal for examining the potential effects of mining because they focus on disturbance, as well as local controls and connectivity.…”

“…An added complication is that some fauna on active vents are shared with those on inactive vents (Gollner et al, 2013;Boschen et al, 2015), so the latter can, under some circumstances, act as source populations after disturbance events. Consequently, the manner in which community dynamics will change in the event of connectivity disruption in the region is difficult to assess (Boschen et al, 2016). Furthermore, the disturbances from mining activities differs from natural disturbance in that they leave behind sediment and rubble (Steiner, 2009), rather than pillow lavas or sheet flows (Chadwick et al, 2001).…”

An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps

“…More than 200 sites of hydrothermal mineralization occur on the seafloor and, based on previous exploration and resource assessment, around 10 of these deposits may have sufficient tonnage and grade to be considered for commercial mining. The technological viability to explore and extract marine mineral deposits is determined by the depth at which the minerals are found (Boschen et al, 2013(Boschen et al, , 2016.…”

Deep‐sea mining: Interdisciplinary research on potential environmental, legal, economic, and societal implications

“…Ridges and inactive vents will take longer to recover because they resemble the ambient deep‐sea environment, where all biogeochemical and biological processes occur very slowly (Williams et al ). In fact, Boschen et al () highlighted that even if habitat is available after mining, it may still take centuries for mature corals and other species to recolonize the area. It is likely that the fauna that has settled on inactive vents after the extinction of active venting would be destroyed.…”