Description: Publication date: Available online 19 January 2018 Source: Journal of Hydrology: Regional Studies Author(s): Alfonso Rivera, Lucila Candela Study region Global scale. Study focus This paper highlights the main outputs and outcomes of the Internationally Shared Aquifer Resources Management Initiative (ISARM, 2000–2015) of UNESCO on the global scale. We discuss the lessons learned, what is still relevant in ISARM, and what we consider irrelevant and why. We follow with discussion on the looming scenarios and the next steps following the awareness on transboundary aquifers (TBAs) as identified by ISARM. New insights for the region This analysis emphasizes the need for more scientific data, widespread education and training, and a more clearly defined role for governments to manage groundwater at the international level. It describes the links, approach and relevance of studies on TBAs to the UN Law of Transboundary Aquifers and on how they might fit regional strategies to assess and manage TBAs. The study discusses an important lesson learned on whether groundwater science can solve transboundary issues alone. It has become clear that science should interact with policy makers and social entities to have meaningful impacts on TBAs. Bringing together science, society, law, policy making, and harmonising information, would be important drivers and the best guidance for further assessments. ISARM can still make contributions, but it could be redesigned to support resolving TBAs issues which, in addition to science (hydrogeology), require considering social, political, economic and environmental factors. ISARM can increase its international dimension in the continents that still lag behind the assessment and shared management of TBAs, such as Asia and Africa.

Description: The manganese nodule belt within the Clarion and Clipperton Fracture Zones (CCZ) in the abyssal NE Pacific Ocean is characterized by numerous seamounts, low organic matter (OM) depositional fluxes and meter-scale oxygen penetration depths (OPD) into the sediment. The region hosts contract areas for the exploration of polymetallic nodules and Areas of Particular Environmental Interest (APEI) as protected areas. In order to assess the impact of potential mining on these deep-sea sediments and ecosystems, a thorough determination of the natural spatial variability of depositional and geochemical conditions as well as biogeochemical processes and element fluxes in the different exploration areas is required. Here, we present a comparative study on (1) sedimentation rates and bioturbation depths, (2) redox zonation of the sediments and element fluxes as well as (3) rates and pathways of biogeochemical reactions at six sites in the eastern CCZ. The sites are located in four European contract areas and in the APEI3. Our results demonstrate that the natural spatial variability of depositional and (bio)geochemical conditions in this deep-sea sedimentary environment is much larger than previously thought. We found that the OPD varies between 1 and 4.5 m, while the sediments at two sites are oxic throughout the sampled interval (7.5 m depth). Below the OPD, manganese and nitrate reduction occur concurrently in the suboxic zone with pore-water Mn2+ concentrations of up to 25 µM. The thickness of the suboxic zone extends over depth intervals of less than 3 m to more than 8 m. Our data and the applied transport-reaction model suggest that the extension of the oxic and suboxic zones is ultimately determined by the (1) low flux of particulate organic carbon (POC) of 1–2 mg Corg m−2 d−1 to the seafloor, (2) low sedimentation rates between 0.2 and 1.15 cm kyr−1 and (3) oxidation of pore-water Mn2+ at depth. The diagenetic model reveals that aerobic respiration is the main biogeochemical process driving OM degradation. Due to very low POC fluxes of 1 mg m−2 d−1 to the seafloor at the site investigated in the protected APEI3 area, respiration rates are twofold lower than at the other study sites. Thus, the APEI3 site does not represent the (bio)geochemical conditions that prevail in the other investigated sites located in the European contract areas. Lateral variations in surface water productivity are generally reflected in the POC fluxes to the seafloor across the various areas but deviate from this trend at two of the study sites. We suggest that the observed spatial variations in depositional and (bio)geochemical conditions result from differences in the degree of degradation of OM in the water column and heterogeneous sedimentation patterns caused by the interaction of bottom water currents with seafloor topography.

Description: The initial, anthropocentric view of the deep ocean was that of a hostile environment inhabited by organisms rendered lethargic by constant high pressure, low temperature and sparse food supply, hence evolving slowly. This conceptual framework of a spatially and temporally homogeneous, connected, strongly bottom-up controlled habitat implied a strong constraint on, or poor incentive for, speciation. Hence, the discovery in the late 1960s of high species diversity of abyssal benthic invertebrates came as a surprise. Since then, the slow-motion view of deep-sea ecology and evolution has speeded up and diversified in the light of increasing evidence accumulating from in situ visual observations complemented by molecular and other tools. The emerging picture is that of a much livelier, highly diversified and more complex deep-sea fauna than previously assumed. In this review we examine the consequences of the incoming information for developing a broader view of evolutionary ecology in the deep sea, and for scavenging amphipods in particular. We revisit the food supply to the deep-sea floor and hypothesize that the dead bodies of animals, ranging from zooplankton to large fish are likely to be a more important source of food than their friable faeces. Camera observations of baited traps indicate that amphipod carrion-feeders arrive within hours at the bait which continues to draw new individuals for days to months later, presumably by scent trails in tidal currents. We explore the different stages of food acquisition upon which natural selection may have acted, from detection to ingestion, and discuss the possibility of a broader range of food acquisition strategies, including predation and specializations. Although currently neglected in deep-sea ecology, top-down factors are likely to play a more important role in the evolution of deep-sea organisms. Predation on amphipods at baits by bathyal and abyssal fishes, and large predatory crustaceans in the hadal zone, is often observed. Finally, we develop hypotheses regarding the effects of past, present and imminent anthropogenic activities on scavenger biomass and how these can be tested with the most modern tools.

Description: Nahezu alle metallischen Rohstoffe, die die Menschheit gegenwärtig benötigt, werden an Land gewonnen. Mit jedem Anstieg der Rohstoffpreise und der zunehmenden Nachfrage einer wachsenden Weltbevölkerung nach neuen Technologien, könnte es attraktiver werden, auch im Meer nach metallischen Rohstoffen zu suchen. Und der Bedarf für den Ausbau der E-Mobilität, die Energiewende und für die zunehmende Digitalisierung aller Lebensbereiche erhöht sich weiter. Die Europäische Union sieht mittlerweile die Versorgung mit 27 strategisch wichtigen Rohstoffen (2017) kritisch. Hierunter fallen beispielsweise Antimon, Germanium oder Kobalt. Die Folgen einer Rohstoffknappheit würden die deutsche Industrie besonders treffen, denn sie ist bei metallischen Rohstoffen nahezu komplett importabhängig. Stellen die Ozeane vor diesem Hintergrund eine attraktive Alternative für die Rohstoffbeschaffung dar? Dieser Frage wollen wir in unserem neuen ESKP-Themenspezial nachgehen. Die Erkundungen nach metallischen Rohstoffen in der Tiefsee sind voll im Gange: im Indischen Ozean, im Pazifik, auf alten Seerücken oder den Flanken submariner Vulkane. Insbesondere Kupfer, Kobalt und Nickel kommen in der Tiefsee in Mengen vor, die mit denen an Land vergleichbar sind. Der Run auf die Erkundungslizenzen hat bereits begonnen und die Unterwasserwelt wird nach und nach aufgeteilt, um den Tiefseebergbau voranzutreiben. So haben sich die Anträge bei der Internationalen Meeresbodenbehörde in den letzten fünf Jahren verdreifacht. Doch ist aus Umweltgesichtspunkten der Abbau metallischer Rohstoffe im Meer überhaupt vertretbar? Welche Auswirkungen auf die marinen Ökosysteme hätten riesige Trübungswolken am Meeresgrund? Wie ausgereift sind die Technologien für den Meeresbodenbergbau? Wie könnte ein zuverlässiges Umweltmonitoring in der Tiefsee aussehen? Wäre es besser nach Einsparmöglichkeiten an Land zu suchen und Alternativen zu erforschen? Viele durchaus strittige Fragen, die wir aus Sicht der Forschung beleuchten wollen.