Alfred Wegener Institute for Polar and Marine Research
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The changing nature of future Arctic marine heatwaves and its potential impacts on the ecosystem
Get PDFAbstractMarine heatwaves (MHWs), defined as extreme ocean warming episodes, have strengthened over the past decades. High-resolution climate models improve understanding of MHWs under global warming, but such events in the future Arctic are currently overlooked. In a high-resolution climate model, we find Arctic MHWs intensify on orders of magnitude during the warming twenty-first century, following sea ice retreat. However, with little sea ice coverage, strong interannual variability emerges, which could surpass the amplitude of former intensification. Furthermore, the enhancement of MHWs correlates with an order of magnitude increase in the rate of change in the temperature anomaly. Additionally, MHWs are found to be accompanied by stratification enhancement, which could surpass interannual variability of future stratification. Such extreme temperature fluctuations combined with stratification enhancement suggest major challenges for Arctic ecosystems, and may negatively impact food webs through direct physiological temperature effects, as well as indirectly through nutrient supply and taxonomic shifts.</jats:p
Lena River biogeochemistry captured by a 4.5-year high-frequency sampling program
Get PDFThe Siberian Arctic is warming rapidly, causing permafrost to thaw and altering the biogeochemistry of aquatic environments, with cascading effects on the coastal and shelf ecosystems of the Arctic Ocean. The Lena River, one of the largest Arctic rivers, drains a catchment dominated by permafrost. Baseline discharge biogeochemistry data are necessary to understand present and future changes in land-to-ocean fluxes. Here, we present a high-frequency 4.5-year-long dataset from a sampling program of the Lena River's biogeochemistry, spanning April 2018 to August 2022. The dataset comprises 587 sampling events and measurements of various parameters, including water temperature, electrical conductivity, stable oxygen and hydrogen isotopes, dissolved organic carbon concentration and 14C, colored and fluorescent dissolved organic matter, dissolved inorganic and total nutrients, and dissolved elemental and ion concentrations. Sampling consistency and continuity and data quality were ensured through simple sampling protocols, real-time communication, and collaboration with local and international partners. The data are available as a collection of datasets separated by parameter groups and periods at https://doi.org/10.1594/PANGAEA.913197 (Juhls et al., 2020b). To our knowledge, this dataset provides an unprecedented temporal resolution of an Arctic river's biogeochemistry. This makes it a unique baseline on which future environmental changes, including changes in river hydrology, at temporal scales from precipitation event to seasonal to interannual can be detected
Perspective article: Multisectoral considerations to enable a circular economy for plastics
Get PDFPlastics are widely used but improper disposal and release lead to increasing global pollution, threatening environmental and human health. To address this issue, we suggest intersectoral collaboration to achieve zero plastic pollution. The outcomes of the project P-LEACH demonstrated the enormous complexity and range of potential toxic effects of plastic-associated chemicals and micro-/nanoplastics released into water from UV-weathered plastics. We initiated an intersectoral dialogue amongst scientists, manufacturers, regulators and representatives of civil society about how to alleviate the negative impacts of plastic pollution. Circular economy offers a framework for selecting non-toxic chemicals, extending product (re)use, and waste reduction, which act to alleviate pollution when applied to plastics. We suggest three measures to advance a circular economy of plastics: 1.) Increase simplicity of chemicals in virgin plastics combined with transparent information on the contents; 2.) Consider recyclability already in plastic material and product design; 3.) Foster communication through intersectoral dialogue. Major cornerstones are the provision of standardized, easy-to-use tools to characterize plastics and plastic leachates chemically and (eco)toxicologically, the enhancement of citizen awareness enabling them to make informed choices, the creation of economic incentives for manufacturers, and sector-specific regulations to provide products that safeguard environmental and human health
Ecological impacts of wind turbine blade erosion on blue mussels (Mytilus edulis)
Get PDFOffshore wind farms (OWFs) introduce novel anthropogenic pressures to marine ecosystems, including the release of organic and inorganic particles from turbine blade erosion, which may impact marine life. This study investigated the potential effects of these particles and their additives on the metabolic profile of the blue mussel (Mytilus edulis) using 1H-NMR spectroscopy. Mussels were exposed in the laboratory to microplastic (MP) particles derived from cryo-milled rotor blade coatings and core materials (glass fiber polymer, GFP) under a simulated worst-case scenario of extensive blade erosion. Enrichment factors (EFs) for metals and metalloids (e.g., Ba, Cu, Cd, Cr, Ni) ranged from 0.93 to 6.1, indicating a potential chemical load from the rotor blade materials. Untargeted metabolic profiling of mussel tissues revealed no significant disruptions to metabolic pathways, however trends in metabolite levels suggested potential short-term effects on neuroendocrine systems and possible long-term impacts on energy metabolism. Further research is essential to comprehensively evaluate the potential impacts of OWF erosion on marine environments, particularly in light of the planned expansion of wind farm construction as part of the EU-wide energy transition
Uncovering the amphipod diversity of the remote island of Rapa Nui: insights from morphology and DNA barcoding
Get PDFPhysical Mechanisms of Sediment Trapping and Deposition on Spatially Confined Mud Depocenters in High‐Energy Shelf Seas
Get PDFAbstract Mud depocenters in shelf seas serve as a key element in the source‐to‐sink system of sediment transport on the Earth surface. Despite their undoubtful importance, physical mechanisms for formation, sediment budgeting, and cycling of localized depocenters in high‐energy environments remain largely unknown. This study aims to fill the knowledge gap by focusing on sediment dynamics related to a localized mud depocenter in the southern North Sea. By combining field observation with 3‐dimensional numerical simulations, we analyzed hydrodynamics and sediment dynamics over a 3‐year period. Our results indicate a persistent transport of fine‐grained sediments toward the depocenter and subsequent trapping resulting in accumulation, with distinct seasonal and spatial variations in the net depositional rate. The interaction of wind‐driven coastal circulation with two distinct frontal systems—a salinity front and a tidal mixing front—emerges as a key mechanism of sediment dynamics. While the salinity front remains persistently over the depocenter, promoting sediment deposition year‐round, the tidal mixing front appears primarily in summer, limiting sediment deposition. Sediment flows from offshore and along the coast provide major supply to the depocenter, while contemporary riverine sediment outflows contribute only marginally. Southwesterly winds enhance erosion and northerly winds promote deposition in the depocenter. Additionally, short‐term extreme events significantly contribute to annual net sedimentation. Our work highlights the critical importance of frontal systems and extreme events for mud depocenter development in high‐energy shelf seas.
Plain Language Summary Coastal environments constantly change as water moves sediment, forming areas where mud accumulates, known as mud depocenters. However, the processes controlling development of these deposits are not fully understood. This study examines a mud depocenter in the southern North Sea to understand how ocean currents, river flow, tides, and wind influence sediment movement. We found that two key oceanic density fronts—a riverine salinity front and a tidal mixing front—play a crucial role in trapping sediment. The salinity front is present year‐round, while the tidal front appears mainly in summer. The contrasting effects of these two fronts lead to higher sediment accumulation in winter. Wind direction also affects deposition, with southwesterly winds causing erosion and northerly winds promoting deposition. Extreme events like storms and river floods significantly increase sedimentation over short periods. Our results highlight the critical importance of frontal systems and extreme events that shape coastal sedimentation in high‐energy shelf seas. Understanding these processes is especially important for predicting coastal changes, as human activities may also influence sediment dynamics.
Key Points Salinity and temperature frontal systems jointly control sediment trapping and deposition in energetic shelf seas Despite seasonal variations in the frontal systems, persistent sedimentation occurs in the mud depocenter Sedimentation on the mud depocenter is promoted by storms and flood
Hydrothermal mobilization and molecular transformations of dissolved organic matter from deep subsurface sediments
Get PDFCarbon mobilization in hydrothermal sediments and advective transport of dissolved organic matter (DOM) to the ocean affect deep-sea ecosystems. However, the link between hydrothermal processes and DOM reactivity in organic-rich subsurface sediments, and the impact of DOM release on the marine carbon cycle remain poorly understood. The Guaymas Basin (Gulf of California), with its organic-rich sediments, hydrothermal vent sites, and magmatic sill intrusions is an ideal candidate for studying the hydrothermal influences on DOM biogeochemistry. We analyzed sediment and porewater samples from IODP Expedition 385 from down to ∼330 m below seafloor and used hot-water Soxhlet extractions as a first-order approximation for simulating hydrothermal DOM mobilization. We assessed the molecular composition of solid-phase extractable (SPE) DOM via ultrahigh-resolution mass spectrometry (FT-ICR-MS) and quantified dissolved organic sulfur, nitrogen, and phosphorus (DOSSPE, DONSPE, DOPSPE). We identified several biogeochemical processes transforming DOM: active microbial transformations in the upper sediments were related to enhanced DOM oxygenation, and elevated DONSPE and DOPSPE concentrations. Highly aromatic, probably recalcitrant DOM, accumulated under anoxic conditions in intermediate depths. Here, DOSSPE concentrations were highest, probably due to abiotic sulfide incorporation into DOM. Hydrothermal alteration near magmatic sills reduced DOM molecular diversity and caused a significant shift in the chemical composition of deep subsurface sediments influenced by high temperatures. Our data indicated that hydrothermal sediments release DOM, including DOSSPE, DONSPE and DOPSPE, to the ocean. Hence, hydrothermal discharge may not only sustain local benthic ecosystems by providing bioavailable DOM but also likely influences the deep-sea carbon pool by introducing recalcitrant DOM
Imprint of incomplete combustion processes on the water column of the anthropogenic-pressured Baltic Sea
Get PDFThis study evaluates the distribution and sources of thermogenic organic matter in the Baltic Sea water column, focusing on polycyclic aromatic hydrocarbons (PAH), dissolved black carbon (DBC), and the imprint of thermogenic organic matter on the dissolved organic matter (DOM) pool. The spatial patterns and complex interactions between land-based and atmospheric sources were assessed from Kiel Bay to Pomeranian Bight within the water column with the combined targeted and untargeted approaches. The findings emphasize the significant influence of terrestrial inputs from the Oder River and autochthonous production composing DOM. In the Pomeranian Bight, PAH and DBC concentrations strongly correlate with land-based discharge, while shipping emissions play a more prominent role in the Arkona Sea. The sea surface microlayer shows unique characteristics in DOM composition, with potential combustion products as an important source revealed by PAH and DOM analyses. Ultrahigh-resolution mass spectrometry identified combustion products, in the DOM pool, providing insights into anthropogenic impacts. This research contributes to a better understanding of the complex dynamics of thermogenic organic matter in coastal environments, highlighting the interplay between land-based sources, shipping emissions, and in-situ processes in the Baltic Sea region
Record-breaking extremes in a warming climate
Get PDFNumerous weather and climate extremes have broken long-standing observed records. These record-breaking (or record-shattering if the margin is large) events have substantial socioeconomic impacts and pose adaptation and planning challenges. In this Review, we assess observed and projected changes in record-breaking climate extremes. Record occurrence can be understood with statistical considerations, and their changes quantified as the record ratio — the observed frequency of record events relative to a stationary climate. Many climate variables have witnessed changes in their record-breaking frequency. For example, all-time daily hot records on land are more than four times higher in 2016–2024 than expected without climate change, and all-time cold records two times lower; similarly, daily maximum precipitation records and monthly dryness records are more than 40% and 10% higher, respectively. In the future, slowing the rate of warming reduces record ratios, highlighting the benefits of mitigation. For instance, by the end of the century, multimodel mean record hot events are projected to be 15.7 more likely than in a stationary climate under SSP3-7.0, but only ~2.9 and ~1.8 more likely for SSP1-2.6 and SSP1-1.9, respectively, lower than those observed today. New record cold will become virtually non-existent under all emission scenarios. Among others, records have also been broken for ice loss, sea ice and ocean heat content, but quantifying record statistics is challenged by data availability, duration and quality. Addressing these data challenges and developing statistical methods to account for multivariate records are research priorities