Anthropogenic pressures at the Lucky Strike hydrothermal vent field: 30 years of research activities

The deep sea, the Earth's largest environment, faces increasing threats from human activities. Among the multiple ecosystems, hydrothermal vents harbor unique chemosynthetic communities that are characterized by elevated faunal biomass, high endemicity and low diversity compared to the surrounding environments. These ecosystems are particularly vulnerable but only a few vent sites are included in Marine Protected Areas (MPAs), although they are increasingly targeted by mining industries for their mineral resources. The Lucky Strike (LS) vent field, discovered in 1992, is located within a Portuguese MPA, in the Marine Park of the Azores. It has been visited almost annually, raising concerns about the potential ecological impacts of research activities. We identified and quantified research-related pressures over 33 years through extensive archival data mining, expert assessment, and spatio-temporal analyses of research activities. The Integrated Research Pressure Index developed here can be applied to any ecosystem, providing a standard approach to monitor research pressures. The substantial research footprint included thousands of sampling events, extensive submersible operations, and the deposition of approximately 230 tons of metallic litter, from which vent sites were classified on a scale from "pristine" to "pressurized". A marked increase in research activities was observed following the implementation of the EMSO-Azores observatory in 2010. We provide recommendations for sustainable future research activities and solutions to minimize impacts at hydrothermal vents and other deep-sea ecosystems. This study provides the first human impact assessment at LS, and can thus inform the management plan of the Azores MPA and modulate its future regulations.