Beschreibung: We compare and contrast the ecological impacts of atmospheric and oceanic circulation patterns on polar and sub-polar marine ecosystems. Circulation patterns differ strikingly between the north and south. Meridional circulation in the north provides connections between the sub-Arctic and Arctic despite the presence of encircling continental landmasses, whereas annular circulation patterns in the south tend to isolate Antarctic surface waters from those in the north. These differences influence fundamental aspects of the polar ecosystems from the amount, thickness and duration of sea ice, to the types of organisms, and the ecology of zooplankton, fish, seabirds and marine mammals. Meridional flows in both the North Pacific and the North Atlantic oceans transport heat, nutrients, and plankton northward into the Chukchi Sea, the Barents Sea, and the seas off the west coast of Greenland. In the North Atlantic, the advected heat warms the waters of the southern Barents Sea and, with advected nutrients and plankton, supports immense biomasses of fish, seabirds and marine mammals. On the Pacific side of the Arctic, cold waters flowing northward across the northern Bering and Chukchi seas during winter and spring limit the ability of boreal fish species to take advantage of high seasonal production there. Southward flow of cold Arctic waters into sub-Arctic regions of the North Atlantic occurs mainly through Fram Strait with less through the Barents Sea and the Canadian Archipelago. In the Pacific, the transport of Arctic waters and plankton southward through Bering Strait is minimal. In the Southern Ocean, the Antarctic Circumpolar Current and its associated fronts are barriers to the southward dispersal of plankton and pelagic fishes from sub-Antarctic waters, with the consequent evolution of Antarctic zooplankton and fish species largely occurring in isolation from those to the north. The Antarctic Circumpolar Current also disperses biota throughout the Southern Ocean, and as a result, the biota tends to be similar within a given broad latitudinal band. South of the Southern Boundary of the ACC, there is a large-scale divergence that brings nutrient-rich water to the surface. This divergence, along with more localized upwelling regions and deep vertical convection in winter, generates elevated nutrient levels throughout the Antarctic at the end of austral winter. However, such elevated nutrient levels do not support elevated phytoplankton productivity through the entire Southern Ocean, as iron concentrations are rapidly removed to limiting levels by spring blooms in deep waters. However, coastal regions, with the upward mixing of iron, maintain greatly enhanced rates of production, especially in coastal polynyas. In these coastal areas, elevated primary production supports large biomasses of zooplankton, fish, seabirds, and mammals. As climate warming affects these advective processes and their heat content, there will likely be major changes in the distribution and abundance of polar biota, in particular the biota dependent on sea ice.

Beschreibung: A comprehensive understanding of the deep-sea environment and mining’s likely impacts is necessary to assess whether and under what conditions deep-seabed mining operations comply with the International Seabed Authority’s obligations to prevent ‘serious harm’ and ensure the ‘effective protection of the marine environment from harmful effects’ in accordance with the United Nations Convention on the Law of the Sea. A synthesis of the peer-reviewed literature and consultations with deep-seabed mining stakeholders revealed that, despite an increase in deep-sea research, there are few categories of publicly available scientific knowledge comprehensive enough to enable evidence-based decision-making regarding environmental management, including whether to proceed with mining in regions where exploration contracts have been granted by the International Seabed Authority. Further information on deep-sea environmental baselines and mining impacts is critical for this emerging industry. Closing the scientific gaps related to deep-seabed mining is a monumental task that is essential to fulfilling the overarching obligation to prevent serious harm and ensure effective protection, and will require clear direction, substantial resources, and robust coordination and collaboration. Based on the information gathered, we propose a potential high-level road map of activities that could stimulate a much-needed discussion on the steps that should be taken to close key scientific gaps before any exploitation is considered. These steps include the definition of environmental goals and objectives, the establishment of an international research agenda to generate new deep-sea environmental, biological, and ecological information, and the synthesis of data that already exist.

Beschreibung: SummaryThe aim of this study was to identify scientific criteria and to acquire performance data for the development of mariculture in the context of sustainable multifunctional use of offshore space and natural resources.In connection with current plans for a massive expansion of wind farms in offshore areas of the North Sea, the idea emerged to combine these with the installation of extensive mariculture for bivalves and macroalgae. Since offshore wind farms provide safety from shipping and infrastructure for attachment and service support, the opportunity for a multiple-use concept presented itself. However, prior to such a multifunctional development, it is necessary to determine the appropriate biological, technological and management requirements as well as the performance characteristics that would allow the employment of favourable and cost-effective methodologies. To this end, spezial focus was placed on the combination of extensive offshore shellfish and seaweed farming at exposed sites within the proposed offshore wind farms.This thesis deals in detail with1. the effects of abiotic and biotic factors on the growth potential of indigenous macroalgae and bivalves in extensive mariculture systems exposed to the stressful conditions of offshore habitats: (a) effects of physical forces on the cultivated species, (b) various parameters characterising the growth performance of species, (c) testing these parameters while using a variety of substrates and technical setups, (d) survival and health conditions, (e) recruitment, (f) parasite infestation of mussels in relation to inshore and offshore exposure, and (g) site-specific responses of the species to the various harsh offshore environments,2. the interaction between physical offshore processes and man-made structures in areas of the German North Sea Territory where mariculture has potential,3. the conditions for possible combination of mariculture systems with offshore wind farms in terms of the legal framework and possible management strategies, and4. the socio-economic and legal consequences and interactions for offshore mussel farming with the existing conventional inshore bottom culture activities.The research locations were specifically selected sites in the offshore region of the German Bight, mainly in the outer estuary of the River Weser, the offshore waters off the Island of Helgoland, several offshore areas where wind farms are planned, and habitats along the northern part of the Island of Sylt.In this yet relatively young research field the performance of different offshore culture systems with attached macroalgae (Laminaria saccharina) and blue mussels (Mytilus edulis) was assessed at monthly sampling intervals. These procedures were carried out using research vessels, boats and scuba surveys, while determining morphometric parameters (e.g. length, width, thickness) as well as weight for growth analysis of mussels and seaweeds. Furthermore, the condition index, the meat content and the degree of parasite infestation of blue mussels were determined. The abundance of mussel larvae in the water column and the resulting settlement success of post-larvae on various spat collectors were investigated. Seaweed studies included attachment strength, breaking and drag forces on kelp sporophytes in order to describe the resistance of cultivated Laminarians to high energy environments. Additional assessment criteria were biochemical parameters (e.g. chlorophyll-, nutrient-, POC- and TON-concentrations and their ratios) to describe the food availability for mussels and the nutrient composition for algal growth as well as oceanographic parameters (currents, waves, swell, salinity, temperature, light attenuation) to describe the wave climate and current velocities of the study sites in the offshore environment. Technical studies comprised two system designs (longline, ring structure) of various set ups (submerged or floating mode) in different locations (offshore or inshore) to find an appropriate culture design to sustain growth and survival of cultivated species. Further, a specially designed offshore spat collector was used for settlement investigations of mussel post larvae. Some fundamental studies were carried out in order to pave the way for the realisation of open ocean aquaculture in offshore wind farms (e.g. multifunctional use of offshore habitats in terms of avoidance of stakeholder conflicts, the legal framework for such activities in coastal areas and in the Exclusive Economic Zone (EEZ), the multi-use concept in terms of integrated coastal zone management).Laminaria saccharina showed sufficient length increments in offshore habitats growing on a submerged ring system. It could be demonstrated by drag and breaking-/dislodgement force experiments that algae were capable of resisting the high-energy environment of the North Sea. The concentration of mussel larvae in the water column decreased offshore and resulted in a low settlement success while at the same time infestation load decreased and was lacking at offshore suspended collectors. The three system designs showed different results. While the offshore ring proved to be superior for seaweed cultivation under the harsh conditions, the longline showed some major drawbacks in terms of materials used, design and installation modes (submerged or floating). The spat collector largely withstood the harsh hydrodynamic conditions of the North Sea. The hitherto fragmented legal framework for the offshore waters was found to be one of the key constraints for the successful implementation of multifunctional use schemes. However, participation of all involved stakeholders may provide a window of opportunity to turn the existing lack of offshore regulations into a positive momentum, as scope exists to move with the development of new offshore co-management concepts beyond existing management approaches.Whether such offshore installations would provide sufficient economic returns could not be answered yet, as experience on the maintenance of offshore wind farms is lacking so far.However, the discovery that Laminaria saccharina resists offshore forces and shows sufficient length increments and mussels growing in offshore habitats are not affected by parasites may provide a key incentive for positive commercial use.It thus can be shown that there is a high potential for farming the deep blue in the German EEZ, provided that some of the constraints, of which the lack of legal framework and technical aspects seems to be most severe, are resolved in the near future.

Beschreibung: The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.