REMIND - Monitorização da REcuperação de impactos da MINeração de mar profundo na bioDiversidade bentónica

The general goal of REMIND is to advance knowledge of nodule-rich abyssal ecosystems and their resilience to mining impacts. The planned research focus on macrofaunal communities of 2 license areas in the Clarion-Clipperton Zone (CCZ) and addresses some identified scientific gaps on baseline definition and post-disturbance responses of macrofauna required for environmental planning, monitoring, and management. Thus REMIND will provide science-based support to regulators and contractors. Specific goals can be categorised as: 1. Knowledge of ecosystems - provide accurate identifications and high-resolution biodiversity assessments using integrative taxonomy - provide information on the functional structure of macrofauna using a trait-based approach - assess macrofaunal resilience 2. Impacts of mining - advice on monitoring criteria (indicators, thresholds) by analysing post-mining recovery trends of two types of impact (nodule removal and plumes) - evaluate cumulative effects by conducting a 5yr-long monitoring study 3. Support to stakeholders - provide scientific evidence to inform Environmental Impact Assessments, Environmental Monitoring and Management Plans and technological innovation of collector equipment - assess the applicability of monitoring tools (eDNA approaches for biodiversity assessments and functional diversity indices to monitor recovery trends) REMIND research is based on the scientifically independent monitoring of the mining trial conducted with a collector prototype in the Belgian and German license areas (May 2021, CCZ). Samples and data collected during past and planned cruises will allow, for the first time, replicated monitoring of a mining test over 5 years. This design enables monitoring the macrofaunal responses to nodule removal and sediment plume blanketing, and addressing cumulative effects. These are 3 of the 5 main expected environmental impacts that were never directly evaluated due to absence or limited data. While impacts of nodule removal are very difficult to prevent, assessing the impacts of blanketing by plume sediments is a priority because they can be mitigated by technological improvements of the collector equipment and contractor’s exploration plans. The natural deposition rates in CCZ are very low, and thus even thin blanketing may be detrimental at individual and community levels. REMIND results are expected to inform on potential indicator taxa or functional groups as well as on objectives and thresholds to prevent ‘serious harm’ from blanketing. The nature of the macrofauna communities in the CCZ is a major challenge imposing limited taxonomic resolution and accuracy of biodiversity assessments. It is estimated that 25-75% of the species are yet to be discovered and the communities are characterized by low abundance, high richness and prevalence of singletons. These challenging characteristics will be addressed by using the following approaches: i) Integrative taxonomy (morphological and molecular) – allows for accurate identifications, and new species discovery. ii) Trait-based approaches - will tone down the effects of low abundance and singletons prevalence and better assess the ecological significance of community changes. iii) eDNA approach – allows rapid biodiversity assessments at greater spatial scales. REMIND will evaluate requisites, drawbacks, and applicability of these approaches before recommending their implementation as tools for regulatory monitoring.