Potential Short-Term Effects of Mine Tailings on Phytoplankton Assemblages in the Open Ocean

Abstract

The disposal of mine tailings into the marine environment is considered an essential option to secure the economic efficiency of deep-sea mining, but it might adversely affects the ecosystem. To examine the potential impacts of tailing disposal from polymetallic nodules and polymetallic sulfide mines on phytoplankton communities, addition experiments of crushed fine particles into surface seawater were conducted in the open Indian Ocean and changes in chlorophyll a fluorescence and community composition were analyzed. The addition of tailings had serious adverse effects on phytoplankton fluorescence and photosynthetic activity, regardless of mine type. The adverse effects seemed to mainly be due to the physical properties of the mine tailings. These also showed discriminatory effects on phytoplankton, resulting in great changes in community composition. The results suggest that mine tailings could have significant adverse impacts on phytoplankton assemblages, but the degree of impact greatly varies depending on the phytoplankton groups. The discriminatory impacts would cause changes in biomass, community structure, and thus ecological function.

Socio-Environmental Risks Linked with Mine Tailings Chemical Composition: Promoting Responsible and Safe Mine Tailings Management Considering Copper and Gold Mining Experiences from Chile and Peru

“…Finally, when carrying out technical and economic analyses of alternative ways of disposing of mine tailings, whether on land or in the sea, it is necessary to take into account the lessons learned from the past in many parts of the world, where an analysis was not carried out. Improper management of mine tailings that were deposited in the sea, generating socio-environmental impacts on marine and terrestrial ecosystems that persist to this day, include, for example, the cases of (i) Bahía de Chañaral, Chile, (ii) Bahía de Ite, Peru, and (iii) Bahía de Portman, Spain, among others [ 10 , 32 , 36 , 136 , 137 , 138 , 139 , 140 ]. Considering the lack of information and practical experience on the future effects of implementing the alternative of depositing mine tailings in the sea, it is necessary to apply the precautionary principle and act ethically and responsibly with respect to society and ecosystems.…”

An initial spatial conflict analysis for potential deep-sea mining of marine minerals in U.S. Federal Waters

“…This upwelling of nutrients drives phytoplankton growth that in turn supports higher diversity and biomass of pelagic species compared to other oceanic areas (Morato et al, 2010), such as aggregations of surface sharks, seabirds, and marine mammals (Pitcher et al, 2007). Field experiments show that the open ocean surface water disposal of mine tailings interfered with photosynthesis and phytoplankton growth and diversity (Choi et al, 2022). As such, impaired primary production could impact the base of the pelagic food web and potentially cascade through higher trophic levels with unknown consequences for predators.…”