Publications

This study evaluates bottom trawling intensity and its ecological effects in the Fehmarn Belt (southern Baltic Sea) between 2020 and 2024. The region is dominated by small-scale fishing vessels ( < 12 m length) and therefore conventional Vessel Monitoring System (VMS) data are unavailable. We compare changes in seafloor integrity caused by bottom trawling with fishing activity inferred from Automatic Identification System (AIS) tracking. Trawling intensity was quantified using a previously developed trawling index (TI) based on furrow volume derived from multibeam echosounder (MBES) data. A pronounced alteration in seafloor integrity was observed between 2021 and 2022, with furrow volumes decreasing from 5067 m 3 to 1108 m 3 over an area of 3.4 km 2 . This trend was not recorded by AIS-derived fishing activity, which showed only slight changes in vessel track counts. Spatial and temporal fluctuations in abundance, biomass and community structure were revealed through repeated macrofauna sampling. The fluctuations are likely linked to shifting trawling pressure related to the ban of a fishery targeting cod in the Western Baltic. These biological responses did not follow a linear trend but suggest a dynamic equilibrium may be reached over time. Although MBES data cannot replace AIS for tracking fishing effort, it can supplement and improve the AIS information, providing insights into physical impacts and benthic responses in regions of interest. Integrating MBES-derived indicators identifies the spatial extent of the seabed affected by bottom trawling, thereby strengthening ecological monitoring frameworks and supporting sustainable seabed management, including in marine spatial planning. • Trawling intensity from multibeam surveys improves spatial and ecological monitoring. • In Fehmarn Belt, trawl-induced furrows declined fivefold between 2021 and 2022. • Publicly available AIS data fails to reflect trends in bottom trawling activity. • Over five years, macrofauna response fluctuated non-linearly with trawling pressure. • EEA Reference grid and objective method support alignment across data platforms.

The NW African continental margin is well known for the occurrence of large-scale but infrequent submarine landslides. The aim of this paper is to synthesize the current knowledge on submarine mass wasting off NW Africa with a special focus on the distribution and timing of large landslides. The described area reaches from southern Senegal to the Agadir Canyon. The largest landslides from south to north are the Dakar Slide, the Mauritania Slide, the Cap Blanc Slide, the Sahara Slide and the Agadir Slide. Volumes of individual slides reach several hundreds of cubic kilometres; run-outs are up to 900 km. In addition, giant volcanic debris avalanches are widespread on the flanks of the Canary Islands. All headwall areas are complex with clear indications of multiple failures. The most prominent similarity between all investigated landsides is the existence of widespread glide planes that follow the stratigraphy, which points to weak layers as most important preconditioning factor for the failures. Landslides with volumes larger than 100 m 3 are close to being evenly distributed over time, contradicting previous suggestions that landslides off NW Africa occur at periods of low or rising sea level. The risk associated with the landslides off NW Africa, however, is relatively low due to their long recurrence rates.

The methane flux from coastal water areas such as fjords and the underlying control mechanisms have been little studied to date. Fjords are characterized by a complex hydrography that is shaped by marine and limnic interactions and leads to a pronounced stratification of the water column. The resulting low ventilation of the deep water together with high primary production rates in the surface water and the subsequent transport of the organic material to the seabed often lead to high methane releases from the seabed. In our study, we analyzed a fjord system in the Chilean part of Patagonia, the Golfo Almirante Montt. The investigation is based on studies of water column methane concentration and stable carbon isotopes, the distribution and activity of methane-oxidizing bacteria, and oceanographic and geological observations. Our results indicate that methane is of biogenic origin is released from gas-rich sediments at the entrance of the main fjord basin, which is characterized by pockmarks and gas flares. Tidal currents and turbulent mixing at the sill cause a methane plume near the surface to spread into the main fjord basin and mix with the methane- and oxygen-depleted deep water. The wind-induced mixing at the sea surface controls the methane flux from the methane plume into the atmosphere. The methane plume is consumed mainly by methanotrophic bacteria. An enrichment of the signature gene particulate methane monooxygenase (pmoA) in the methane-poor deep water, and a conspicuously high &amp;#948;13C-CH4 signature of the methane suggest that methane-rich intrusions are periodically introduced into the deep water, which are subsequently converted microbially. Additionally, a &amp;#948;13C-CH4 anomaly in deep water that correlates with a zooplankton accumulation in this depth during daytime is considered to be a product of zooplankton-associated methane production. Our interdisciplinary study offers a comprehensive insight into the complex physical and biological processes that modulate methane dynamics in fjords and thus help to better assess how methane emissions from these systems will change under anthropogenic influence.

After the retreat of the Weichselian glaciers, Northern Europe was populated by highly mobile hunter-gatherer groups. Traces of these societies are difficult to find, hampering our understanding of their life. Some remote basins of the western Baltic Sea, however, only drowned in the Holocene, and it has recently been postulated, that they preserve architectures from the Stone Age, that did not survive on land. In 2021 we documented the Blinkerwall, a stonewall megastructure located in 21 m water depth in the Bay of Mecklenburg, Germany. Shipborne and autonomous underwater vehicle hydroacoustic data as well as optical images show that the wall is composed of about 1700 stones, predominantly less than 1 m in height, placed side by side over 971 m in a way that argues against a natural origin by glacial transport or ice push ridges. Combining this information with sedimentological samples, radiocarbon dates, and a geophysical reconstruction of the paleo-landscape, we suggest that the wall was likely used as a drive lane for hunting during the late Pleistocene or earliest Holocene. Ranging among the oldest hunting structures on Earth and the largest Stone Age structures in Europe, the Blinkerwall will become important for understanding subsistence strategies, mobility patterns, and inspire discussions concerning the territorial development in the Western Baltic Sea region.

Pio XI Glacier (49°S) is the largest and one of the very few advancing glaciers in Patagonia. Satellite data indicate that the main glacier terminus transitioned from calving to land‐based around 2010, effectively resulting in the formation of an ice‐contact delta at the head of Eyre Fjord. Here, we investigate how this ice‐contact delta formation affected sediment transport processes in Eyre Fjord. Sediment cores and seismic profiles collected along the fjord provide evidence for a relatively abrupt increase in the number and magnitude of turbidity currents, coeval with the formation of the ice‐contact delta. This observation is supported by modern summer hydrographic observations and bathymetric data. We posit that the ice‐contact delta formation resulted in sediment input being concentrated at specific subaerial locations across the fjord head, which favoured the development of plume‐triggered turbidity currents. This suggests that a sudden increase in turbidite thickness in fjord sediment records could represent ice‐contact delta development at fjord heads.

No abstract is provided for this article.

A newly identified large-scale submarine landslide on the NW African margin (Agadir Slide) is investigated in terms of its morphology, internal architecture, timing, and emplacement processes using high-resolution multibeam bathymetry data, 2D seismic profiles, and gravity cores. The Agadir Slide is located south of the Agadir Canyon at a water depth ranging from 500 m to 3,500 m, showing an estimated affected area of approximately 5,500 km2. The analysis of the Agadir Slide's complex morphology reveals the presence of two headwall areas and two slide fairways (the Western and Central slide fairways). Volume calculations indicate that ∼340 km3 of sediment were accumulated downslope along the slide fairways (∼270 km3) and inside the Agadir Canyon (∼70 km3). Stratigraphic correlations based on five gravity cores indicate an emplacement age of 142 ± 1 ka for the Agadir Slide. However, its emplacement dynamics suggest that the slide was developed in two distinct, successive stages. The presence of two weak layers (glide planes) is a major preconditioning factor for the occurrence of slope instability in the study area, and local seismicity related to fault activity and halokinesis likely triggered the Agadir Slide. Importantly, the Agadir Slide neither disintegrated into sediment blocks nor was transformed into turbidity currents. The emplacement timing of the Agadir Slide does not correlate with any turbidites cored downslope across the Moroccan Turbidite System.

Atlantis II Deep, a submarine basin of the Red Sea, is noteworthy because of its hydrothermally active brine pools. High-resolution temperature records fro

Carbon capture and storage (CCS), both on- and offshore, is expected to be an important technique to mitigate anthropogenic effects on global climate by isolating man-made carbon dioxide (CO2) in deep geological formations. In marine environments, however, the potential impacts of CO2 leakage, appropriate detection methods, and risk and pathways of atmospheric emissions are poorly defined. The natural CO2 gas seeps that occur in the relatively shallow waters off the coast of Panarea Island (Aeolian Islands, Italy) can be studied as a large-scale, real-world analogue of what might occur at a leaking offshore CCS site and what tools can be used to study it. The oceanographic survey PaCO2 was performed aboard R/V Urania from 27 July – 01 August 2011 (Naples – Naples). The project’s ship-time was funded by Eurofleets, with work being performed as a sub-project of the Seventh Framework Programme projects “ECO2” and “RISCS”, which provided subsidiary funding. Large amounts of data and samples were collected during the cruise which will be interpreted in the coming months, with preliminary results detailed here. Of particular importance was the discovery of much larger areas showing gas seepage than previously reported. Interdisciplinary measurements were performed at the Panarea seepage site. The international team of scientists onboard R/V Urania performed complementary sampling and measurements for biological, chemical, and physical parameters throughout the area. Together with the dedication of R/V Urania’s Captain and crew, and the eagerness and cooperation of the scientific crew, we were able to obtain excellent scientific results during this six-day cruise.

Hydroacoustic remote sensing represents a non-invasive, repeatable approach to monitoring benthic communities, supporting sustainable management, conservation efforts, and the detection of environmental change. Mussel clusters on a sandy seafloor in the Oder Bank area (10 to 15 m water depth, southwestern Baltic Sea) were detected in high-frequency backscatter data recorded with a Norbit STX multibeam echosounder in 2019. The blue mussel ( Mytilus edulis ) complexes appear as narrow bands in backscatter mosaics, showing average backscatter intensity increases between 0.2 and 1.0 dB, with localized peaks of up to 2 dB compared to the surrounding sand. Mussel coverage, verified by underwater video sledge observations, reaches up to 50% in isolated patches but typically remains below 15%. The acoustic response of the mussel clusters shows a weak to moderate yet significant correlation with mussel cover, independent of frequency (tested at 200, 400, and 700 kHz). This response is observed at incidence angles greater than 40°. A persistent shell hash layer found at 8 cm depth in sediment cores was not detected acoustically at any frequency. Comparison with data from 2024 suggests that these mussel clusters are ephemeral. Due to the shallowness of the Oder Bank they are influenced by natural processes such as wind and current-driven circulation. This causes the Mytilus bands to roll back and forth on the sand, but can also lead to the dissolution and dispersal of the clusters. The mussel complexes cannot be reliably captured using point-based sampling and short video transects. • Mytilus edulis clusters on sand are detectable in multibeam backscatter data. • Change in mussel abundance explains changes in backscatter intensity. • The clusters are short-lived features and not detected in repeated surveys.

. Knowledge about the timing, amplitude and spatial gradients of Holocene environmental variability in the circum-Baltic region is key to understanding its responses to ongoing climate change. Based on a multi-dating and proxy approach, we reconstruct changes in productivity using total organic carbon (TOC) contents in sediments of Lake Kälksjön (KKJ) from west–central Sweden spanning the last 9612 (+255/-114) years. An exception is the period from 1878 CE until today, in which sedimentation was dominated by anthropogenic lake level lowering and land use. In-lake productivity was higher during periods of warmer winters with shortened ice cover and prolonged growing seasons. A multi-millennial increase in productivity throughout the last ∼ 9600 years is associated with progressively warmer winters in northwestern Europe, likely triggered by the coinciding increase in Northern Hemisphere winter insolation. Decadal to centennial periods of higher productivity in KKJ tend to correspond to warmer winters during a more positive North Atlantic Oscillation (NAO) polarity, as reconstructed for the last 8000 years. In consequence, we assume our decadal to centennial productivity record from KKJ sediments for the complete ∼ 9600 years to provide a qualitative record of NAO polarity. A shift towards higher productivity variability at ∼ 5450 cal a BP is hypothesized to reflect a reinforcement of NAO-like atmospheric circulation variability, possibly driven by more vigorous changes in North Atlantic deep-water formation.