Mining the ocean floor for minerals, a practice anticipated to support the production of electric-vehicle batteries and electronics, could have detrimental consequences for deep-sea jellyfish, according to the first study assessing mining impacts on water-column-dwelling animals. The study suggests that sediment stirred from mining sites might trigger stress responses in jellyfish, potentially harming their health.
Proponents of commercial sea-floor mining argue that it is essential for sourcing minerals like cobalt and manganese. However, scientists caution that insufficient knowledge about potential impacts on deep-sea ecosystems, particularly the water column, poses risks to marine life.
The study, co-led by Vanessa Stenvers, a marine ecologist at the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany, focused on deep-sea helmet jellyfish (Periphylla periphylla) collected from Norwegian fjords. The research exposed these jellyfish to varying concentrations of sediment, representative of what they might experience at a mining site.
Results indicated that sediment concentrations above 17 milligrams per litre induced acute stress responses in jellyfish. The animals displayed signs such as excessive mucus production and particles sticking to their bodies. Over 30% of jellyfish bodies were covered in mucus after exposure to the highest sediment concentrations for 24 hours. Such stress responses, if prolonged, could lead to starvation as the energy required for mucus production is substantial.
Moreover, jellyfish at higher sediment concentrations doubled their respiration rate, indicating increased energy demand. Genes related to energy metabolism, wound repair, and the immune system were overexpressed in jellyfish producing excessive mucus.
The study underscores the potential threats to biodiversity and crucial ecosystem functions such as carbon sequestration and nutrient cycling if other gelatinous organisms in the deep ocean respond similarly. The findings emphasize the need for more comprehensive research before approving large-scale deep-sea mining operations.