IFM-GEOMAR

The productivity of the ocean is limited by the transport of nutrient-rich deep waters to the sun-lit surface layer. In large parts of the global ocean this transport is blocked by a temperature-induced density gradient, with warm light waters residing on top of heavier cold waters. These regions, which are referred to by scientists as ocean deserts, are presently expanding due to surface-ocean warming. Enhancing the upward transport of nutrient-rich deep waters through artificial upwelling can break this blockade and make these waters more productive. Forced upwelling of deep-ocean water has been proposed as a means to serve three distinctly different purposes: (1) to fuel marine primary production for ecosystem-based fish farming; (2) to enhance the ocean’s biological carbon pump to sequester CO2 in the deep ocean; (3) to utilize the surface to deep-ocean temperature gradient to generate renewable energy via Ocean Thermal Energy Conversion (OTEC). Whereas theoretical and technical aspects of applying artificial upwelling for these purposes have been studied to some extent, the ecological responses and biogeochemical consequences are poorly understood. Ocean artUp therefore aims to study the feasibility, effectiveness, associated risks and potential side effects of artificial upwelling in increasing ocean productivity, raising fish production, and enhancing oceanic CO2 sequestration. This will be addressed through a combination of experiments at different scales and trophic complexities, field observations of eddy-induced upwelling in oligotrophic waters, and ecosystem-biogeochemical modelling of pelagic systems fertilized by nutrient-rich deep waters. If technically feasible, ecologically acceptable, and economically viable, the use of artificial upwelling for ecosystem-based fish farming could make an important contribution to an ecologically sustainable marine aquaculture.

The geological record shows that volcanic flank collapses and their associated tsunamis are among the largest and most disastrous natural processes on Earth, because of the huge energies involved. The potential impact of such rare but devastating natural disasters is largely ignored by society, leaving us totally unprepared even to detect the precursors of impending catastrophe. Geodetic monitoring documents gradual (cm/yr) down-sliding of individual flanks at many volcanoes worldwide. Such movements express structural instability, and the majority of volcanoes exhibiting slow flank sliding today have experienced flank collapses in the geological past. There is mounting evidence that such collapses were preceded by slow sliding, leading to the hypothesis that gradual flank movement at some point transitions into collapse. This link, however, lacks a physical explanation, and so identifying which slow-sliding precursors might indicate imminent collapse (and therefore what indicators might be used for hazard mitigation measures) is presently impossible. There appear to be two testable mechanisms by which slow sliding could turn into collapse: (i) it results from decrease in the flank’s shearing resistance, or (ii) enhanced activity in the magma system leads to a run-away feedback situation between sliding and depressurization. PRE-COLLAPSE will test these mechanisms on four volcanoes (Anak-Krakatau, Ritter, Etna, Kilauea) by employing advanced computer models capable of simulating both flank sliding and its interaction with the magma system, incorporating rock mechanical behaviours at shear velocities matching those of slowly sliding flanks, and detailed shoreline-crossing interior structures of the volcanoes based on observational data. The outcome will revolutionize how we assess volcanic flank collapse risk, a Gaussian improbability but a societal catastrophe. It will enable us to develop monitoring strategies to detect precursory signals to catastrophic collapse.

Climate change is impacting global ecosystems, especially in the polar areas of the Earth. Countering climate change effects is stated as one of the key goals of both global development, in the 2030 Agenda for Sustainable Development, and of regional development, e.g. EU strategy of managing the Arctic. Cephalopoda (Phylum Mollusca) are pivotal components in marine food webs and have life history and physiological characteristics that make them potential winners of climate change. This group, due to their ecology and biology features, such as high abundance coupled with low taxonomic diversity, high degree of opportunism, ecological adaptability, single reproductive cycle and typically a short lifespan, cab ve used to assess and predict climate change-induced shifts of Arctic ecosystems. Thus, the main objective of the Action is to assess biodiversity, life histories and ecological role of cephalopods in the Arctic and their ontogenetic and temporary changes using both well-established and innovative methodologies, in the climate change context. The project addresses this matter via 3 scientific work packages that focus on the following research hypotheses: Hypothesis 1) diversity and distribution of current Arctic cephalopod populations shifts due to climate changes; Hypothesis 2) environmental conditions experienced during the life of individual cephalopods can be documented and used to assess the climate change impact on life histories, where comparing historical with new specimens will highlight climate change impact; and Hypothesis 3) the role of cephalopods in the Arctic food web is even more pivotal then we currently understand, and this would be tested with innovative food web modelling methods. The results achieved will increase the quality of ecological monitoring in the Arctic, leading to more rational management of the Arctic marine ecosystems in order to possibly counter climate change impact.

With an increasing importance of green technologies, today’s world relies on an increasing supply of minerals. As the discovery of large deposits of strategic minerals—such as copper and gold—is becoming rare, explorers now focus on the deepsea to ensure demand is met. We know since decades that large copper, silver and gold-rich volcanic-hosted massive sulphide deposits are associated with seafloor arc volcanism. Therefore, understanding arc volcanism and in particular the source and transport of copper, silver and gold in arc lavas is critical in understanding how, when and why these deposits form. The Kermadec arc offshore New Zealand is arguably the world’s most hydrothermally active volcanic arc. Here, hydrothermal mineralization and the highest copper and silver contents occur in southern Kermadec arc lavas formed above thick subducting plateau crust. This suggests that the composition and thickness of the subducting plate strongly affects the flux and transport of these metals beneath arcs. However, the processes surrounding the source and transport of copper, silver and gold remain unknown. To fill this knowledge gap we will analyse, at high precision, copper, silver and gold in volcanic glasses (and melt inclusions) at GEOMAR/University of Kiel and compare the results from the northern and southern Kermadec arc. This will enable us, for the first time, to determine the extent to which the thickness and composition of the subducting slab influences copper, silver and gold contents within arc volcanoes. It will also allow us to quantify the amount of these elements that is being removed from the melt during its evolution and ascent. Understanding the processes behind the source and transport of strategic metals will provide vectors for explorers to discover new mineral deposits. Our GoldTrace project has the potential to provide a globally applicable model delineating where and why explorers can expect to find hydrothermal mineralization on the seabed.