The London Workshop on the Biogeography and Connectivity of the Clarion-Clipperton Zone

Recent years have seen a rapid increase in survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ) abyssal plain, a vast area of the central Pacific that is currently being actively explored for deep-sea minerals (ISA, 2016). Critical to the development of evidence-based environmental policy in the CCZ are data on the biogeography and connectivity of species at a CCZ-regional level. The London Workshop on the Biogeography and Connectivity of the CCZ was convened to support the integration and synthesis of data from European Union (EU) CCZ projects, supported by the EU Managing Impacts of Deep-Sea Resource Exploitation (MIDAS) and EU Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans) projects. The London Workshop had three clear goals: (1) To explore, review and synthesise the latest molecular biogeography and connectivity data from across recent CCZ cruises from both contractor and academia-funded projects; (2) To develop complementary and collaborative institutional and program-based academic publication plans to avoid duplication of effort and ensure maximum collaborative impact; (3) To plan a joint synthetic data publication highlighting key results from a range of planned molecular biogeography/connectivity publications. 32 participants attended the workshop at the Natural History Museum in London from 10-12 May 2016. Presentations and discussions are summarised in this report covering (1) overviews of current CCZ environmental projects, (2) policy and industry perspectives, (3) synthesis of DNA taxonomy and biogeography studies, (4) summaries of the latest population genetic studies, (5) summaries of the latest broader morphological context, (6) an overview of publication and proposal plans to maximise collaborative opportunities and finally a series of workshop recommendations

Meiofaunal communities in the Clarion-Clipperton Zone: geographic distribution and link with environmental conditions

Polymetallic nodule mining in the abyss is a nascent industry hoping to meet the growing worldwide demand for metallic minerals. Given that prospective mining is likely to have a profound impact on deep seafloor communities, knowledge on their wider geographic distribution is pivotal in order to provide sound guidelines for environmentally sustainable mining practices. We therefore studied benthic meiofaunal communities spread along four prospective mining areas and one non-mining Area of Particular Environmental Interest in the Clarion-Clipperton Zone (CCZ) of the east Pacific Ocean. Meiobenthic abundance in the upper sediment layer followed an eastward increase in particulate organic matter input, indicating their dependence upon water-column processes. Additionally, standing stock was clearly correlated with the degree of nodule coverage at the different prospective mining areas, with high nodule coverage leading to less sediment volume and thus lower numbers. Future nodule removal through mining activities might therefore lead to an increase in numbers for smaller-sized benthic taxa.In terms of community composition, nematodes were the most abundant meiobenthic taxon, yet showed no pronounced variation in diversity or genus composition between the different mining and non-mining areas. Assemblages were typically dominated by a few genera accounting for the majority of community totals, as well as a large number of rare genera contributing only little to overall abundances. Dominant genera were widely spread within the CCZ and shared among all sampled areas, whereas rare genera were usually limited to one area. The same trend was present when looking at the level of morphospecies, implying that it might be mainly those taxa with a more limited spatial distribution that will be affected by changes in their habitat and/or reduced connectivity between different areas