Alfred Wegener Institute for Polar and Marine Research
Electronic Publication Information CenterNot a member yet
52828 research outputs found
Sort by
Enabling Climate Change Adaptation in Coastal Systems: A Systematic Literature Review
Get PDFClimate change poses increasingly severe risks for coastal ecosystems and coastal communities all around the globe. This condition requires implementing climate adaptation policy and advancing scientific knowledge to adapt to the current and future climate risks. However, implementing climate adaptation policy in coastal areas is still in its infancy. This paper provides insight into 650 peer-reviewed empirical research studies on coastal climate adaptation from the past two decades, providing global evidence on the status quo and distilling six relevant research gaps: (a) minimal contribution to the implementation phase of the adaptation policy cycle; (b) geographical imbalance toward specific ecoregions and coastal sub-systems; (c) less attention to regional scale; (d) lack of sectoral integration; (e) poor contextualization within policy and coastal governance instruments and management arrangements; (f) limited economic and financial focus. Therefore, this paper identifies areas where future empirical research can help fill current knowledge gaps and improve coastal communities' ability to adapt to climate change. This increased knowledge will enhance the resilience of coastal social-ecological systems in the face of environmental challenges
The Impact of Leaching on Radiocarbon Ages of Small-sized Foraminifera Samples
Get PDFReliable radiocarbon (14C) ages of foraminifera are a prerequisite to generate robust high-resolution age-depth models or to obtain precise understanding of past carbon cycle dynamics. With the advance of small-scale 14C measurements, instrumental precision and levels of contamination (extraneous carbon introduced during sample pretreatment or analysis) became increasingly important to consider. To reduce the effect of carbon contamination, an attempt can be made to remove it by leaching the surface with weak acids. Alternatively, mathematical corrections (e.g., subtraction) based on processing blanks can be applied. We report on 14C analyses of monospecific foraminifera samples compared between different blank corrections (correction against 14C-free CO2, IAEA-C1 and foraminifera) and sample treatments (i) to examine whether chemical pretreatment and mathematical blank subtraction are comparable, and (ii) to determine limitations hindering reliable 14C dating with ever smaller sample sizes. The data show that chemical pretreatment of foraminifera corrected against IAEA-C1 does remove surface contamination and that the same effect can be achieved for untreated samples that were mathematically corrected for blank values determined from sample size-matched 14C-free foraminifera. Leaching only has a beneficial effect on 14C data for older samples, where the isotopic difference between untreated and chemically pretreated samples exceeds the analytical precision
Lithium incorporation and isotopic fractionation in large benthic foraminifera under decoupled pH/DIC conditions
Get PDFThe chemical weathering of continental silicate rocks removes CO2 from the atmosphere and exerts a fundamental control on the Earth’s climate over geological timescales. Characterizing silicate weathering in the past is therefore crucial for understanding the climate system. The lithium isotopic composition (δ7Li) of carbonates is considered to be a reliable archive of past seawater δ7Li values, which are useful as a tracer of silicate weathering. However, the Li isotopic fractionation during biogenic carbonate formation is complex, and local conditions such as carbonate system parameters could impact δ7Li values in marine calcifiers. For example, δ7Li values have been shown to be dependent on either pH or DIC in two studies using large benthic foraminifera. Those results are enigmatic, since both studies used similar species of the genus Amphistegina but reported differing controls on δ7Li values.
The aim of this study was to address the earlier contradictory results on the Li isotope behaviour in the hyaline species Amphistegina lessonii. We performed culture experiments under decoupled pH/DIC conditions, and analysed the δ7Li values and Li/Ca ratios in the foraminifera tests. Two different light treatments (light/dark and dark) were also implemented to investigate the potential role of the symbionts.
Contrary to the two previous studies, no links between either pH or DIC and δ7Li or Li/Ca values were observed for any of the treatments in our experiments. Additionally, growth rates also did not seem to influence the Li incorporation or isotopic fractionation. However, an effect of different light treatments was observed, probably due to different physiological processes of the symbionts occurring in dark conditions. Overall, these findings appear to support the use of Li isotopes in large benthic foraminifera to reconstruct past seawater chemistry and to infer changes in chemical weathering during carbon cycle perturbations over the last several hundred million years of Earth history
Brown shrimp (Crangon crangon) processing remains enhance growth of Pacific Whiteleg shrimp (Litopenaeus vannamei)
Get PDFUnderutilized seafood by-products bear considerable potential to reduce economically and environmentally unsustainable fish meal and oil use in aquaculture feeds. The current study investigated the suitability of brown shrimp, Crangon crangon, processing remains (BSPR) as feed ingredient for Pacific Whiteleg shrimp, Litopenaeus vannamei. Two controlled feeding trials with juvenile L. vannamei were conducted to determine growth performance, feed utilization, digestive enzyme activities, and haematological parameters. In a preliminary feeding trial, shrimp showed best weight gain with diets replacing 50% of fishmeal with BSPR when compared to the control (p = 0.003). Muscle tissue (moisture, protein, lipid) and digestive enzyme activities were not affected by diet. The daily molting ratio increased significantly (p = 0.005) with high BSPR inclusion levels and a higher molting synchronicity was observed. The second feeding trial with diets representing 0, 20, 40, 60, 80, and 100% replacement of fishmeal with BSPR showed significantly enhanced growth when replacement exceeded 60%. Concomitantly, feed conversion ratios improved by up to 37% when BSPR was included in higher proportions than fishmeal. Shrimp haematology (protein, haemocyanin, phenoloxidase activity, prophenoloxidase activity) was not affected by dietary treatment, suggesting good health and nutritional status of the shrimp. Brown shrimp processing remains are a nutritive valuable, growth promoting feed ingredient for L. vannamei
Batagay megaslump: A review of the permafrost deposits, Quaternary environmental history, and recent development
Get PDFThe Batagay megaslump, in the Yana Uplands of northern Yakutia, Russia, is the largest known retrogressive thaw slump in the world. The slump exposes a remarkable sequence of Ice Age permafrost deposits that record the interaction of colluvial, eolian and periglacial processes on a hillslope episodically forested during the last 650 ka or more in response to climate variability on glacial–interglacial timescales. Numerous bones, teeth, and occasional carcasses of Pleistocene and Holocene mammals have been recovered from the permafrost. The megaslump developed over the course of several decades in three stages: (1) gullying, (2) thaw slumping, and (3) megaslumping. After disturbance to the taiga vegetation cover in the 1940s–1960s, a hillslope gully formed by the early 1960s. The gully initiated thaw slumping along its central part during the 1980s, with the slump enlarging to megaslump (>20 ha) proportions during the 1990s. By 2019, the area of the slump had reached about 80 ha and its headwall above the slump floor was up to about 55 m high. The main geomorphic processes of slump growth are headwall ablation and thermal erosion, producing a distinctive terrain of icy badlands on the slump floor. Though much of the megaslump is rapidly growing at present, it will probably stabilize eventually as an irregular terrain characterized by sandy ridges and sand-filled elongate depressions formed by degradation of the badlands. Comparison of the Batagay megaslump with megaslumps from northwest Canada reveals several similarities and differences in terms of their geomorphology, permafrost deposits, and Quaternary history
Multi-use of offshore wind farms with low-trophic aquaculture can help achieve global sustainability goals
Get PDFMulti-use of offshore wind farms with low-trophic aquaculture could provide sustainable energy, nutritious seafood, and restorative ecosystem services through nutrients and carbon capture and utilization. In a transition zone between marine and brackish seas, our model predicted that allocating 10% of projected wind farm areas to blue mussel and sugar kelp aquaculture in the North Sea - Baltic Sea transition zone could yield 18 t-fresh weight ha−1 yr−1. Total carbon captured and harvested from seaweed biomass and mussel shells would equal 40% of the carbon dioxide emissions from the Danish agricultural sector. Furthermore, global aquaculture production is projected to increase by 132% compared to current production. With technological and regulatory challenges still to be addressed, these findings demonstrate a vast potential of multi-use in offshore areas, which can generate blue biomass with fewer user conflicts, while mitigating eutrophication and climate change, thereby supporting multiple global sustainable development goals
From lipophilic to hydrophilic toxin producers: Phytoplankton succession driven by an atmospheric river in western Patagonia
Get PDFPhytoplankton succession is related to hydroclimatic conditions. In this study we provide the first description of a toxic phytoplankton succession in the Patagonian Fjord System. The shift was modulated by atmospheric-oceanographic forcing and consisted of the replacement of the marine dinoflagellate Dinophysis acuta in a highly stratified water column during austral summer by the diatom Pseudo-nitzschia calliantha in a mixed water column during late summer and early autumn. This transition, accompanied by a change in the biotoxin profiles (from lipophilic dinophysis toxins to hydrophilic domoic acid), was induced by the arrival of an intense atmospheric river. The winds in Magdalena Sound may have been further amplified, due to its west-east orientation and its location within a tall, narrow mountain canyon. This work also documents the first known appearance of toxic P. calliantha in Northern Patagonian. The potential impacts of the biotoxins of this species on higher trophic levels are discussed
The Amazing Structural Variability of Phycotoxins and Implications for Monitoring and Regulation
Get PDFDecadal variability of eddy temperature fluxes in the Labrador Sea
Get PDFSmall-scale eddies play an important role in preconditioning and restratifying the water column before and after mixing events, thereby affecting deep water formation variability. Results from a realistic eddy-resolving (∼5 km local horizontal resolution) ocean model suggest that small-scale temperature fluxes due to turbulent potential to kinetic energy conversion are the main driver of mixed layer restratification during deep convection in the Labrador Sea interior and the West Greenland Current. This resupply of heat due to turbulent upward buoyancy fluxes exhibits a large interannual variability imposed by the atmospheric forcing. Eddy fluxes only become active in periods of strong buoyancy loss, while being quiescent otherwise. In a low-resolution (∼20 km) control simulation the modeled turbulence is strongly reduced and the associated modeled and parameterized heat fluxes are too weak to increase stratification