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8. Wochenbericht SO314
No full textForschungsfahrt des FS SONNE SO 314: T-SECTOR Southeast Pacific Rise: 13.08.2025 (Papeete/Tahiti) – 05.10.2025 (Antofagasta/Chile)
8. Wochenbericht: 29.09.-04.10.202
Visualization of the Linux Kernel With ExplorViz
No full textThe Linux kernel is one of the largest and longest-maintained open-source projects in existence. With tens of thousands of source code files, understanding the program’s internal structure and behavior is a great challenge. In this paper, we present an approach to visualize the Linux kernel using our software visualization tool ExplorViz. We analyze commits from the Linux Git repository using srcML and our custom backend service for static analysis. We visualize the folder structure and included source code files using the city metaphor. Users can visually compare the structure of different commits to gain insight into the kernel’s software evolution.In addition to the visualization of the structure of the Linux kernel, ExplorViz processes traces that provide runtime information about the kernel’s behavior. Therefore, we employ the function tracer ftrace and convert the gathered traces to the OpenTelemetry format. The accumulated traces are displayed as arcs between communicating files.When combined with the numerous configuration options of ExplorViz for customizing its visualization, our approach offers new and versatile perspectives on the Linux kernel.Video URL: https://youtu.be/cBouE5eQOj
Louisville Ridge Seamount Chain— V p/ V s investigation of seamount structure and subduction-related deformation
No full textTomographic inversion of traveltime picks from both P-wave and S-wave wide-angle seismic data acquired along and across the Louisville Ridge Seamount Chain (LRSC) provides key insights into its magmatic construction and subsequent subduction-related deformation. Our P-wave velocity-depth models reveal that each seamount along the LRSC comprises an intrusive mafic–ultramafic core that rises within the crust to within 1–2 km of the seabed summit (P-wave velocity, Vp = 5.5–6.5 km s−1; S-wave velocity, Vs < 3.6 km s−1), with each underlain by a crustal root ∼4–5 km thick. Notably, Canopus seamount comprises two adjacent eruptive centres, and our modelling shows that the more northern is currently being internally deformed as it rides up (ascends) the Tonga-Kermadec Trench (TKT)-related plate bending outer rise. Lateral variation in Vs within models along and across the LRSC also primarily reflects subduction-related deformation, with low-velocity regions corresponding to large-scale faulting constrained within the crust. Comparison of pre- and post-LRSC-TKT collision forearc crustal structure indicates that bulk Vp properties recover within ∼50 kyr, whereas Vs structure retains it fault-related fabric for at least ∼740 kyr. Vp/Vs ratios (1.75–1.85) confirm a magmatic origin for all LRSC seamounts, with evidence of localized water-filled cracks due to seawater infiltration along faults, particularly beneath the TKT-ward side of Osbourn seamount. Estimated water content within the upper crust ranges from 12 to 15 per cent by weight, decreasing to < 10 per cent in the mid-lower crust, with no evidence of > 12 per cent water content within the Pacific crust being subducted. In comparison with post-collision subduction further north, where the observed upper mantle velocity suggests up to 30 per cent water content, our models suggest that, although deformed and faulted as part of subduction, the LRSC appears more resistant to this deformation than the background Pacific crust adjacent. Our findings provide new constraints on the mechanical and compositional evolution of the LRSC, both prior to and during its collision with the overriding Indo-Australian plate
Reconstructing and tracking partially cloud-obscured dust plumes in the Bodélé Depression
No full textRecognizing adaptation costs in the Anthropocene
No full textHighlights:
- Efforts to understand limits on evolutionary rescue in response to rapid environmental change have emphasized adaptation constraints, but adaptation costs are often overlooked.
- A growing number of studies have shown that adaptation costs are common and can limit evolutionary rescue, impeding population/species conservation efforts.
- A failure to account for adaptation costs can lead to inaccurate and potentially overly optimistic predictions of population resilience.
Quantifying and incorporating adaptation costs into evolutionary rescue models would improve predictions of responses of populations to rapid global change.
Abstract:
While populations can adapt to rapid environmental change in the Anthropocene, adaptation costs may limit evolutionary rescue, even when standing population genetic variation is high. Here, we argue that adaptation costs are linked to evolutionary trade-offs involving scenario- or system-specific traits that usually promote environmental specialization and species coexistence. Adaptation costs can be cryptic, and are more likely to emerge in populations under fluctuating environments or under multiple stressors. Adaptation costs mediated by ecological processes such as competition and symbiosis can limit population growth and species ranges. We advocate for considering adaptation costs in global change studies to improve predictions of future population responses, biological production, and ecosystem resilience
Confirmation of hard-substrate predictions in the abyssal Vema Fracture Zone
No full textHydroacoustic mapping has recently challenged the long-held view of a uniform abyssal seafloor by predicting substantial habitat heterogeneity in this environment. The RUBBLE expedition M205 validated these predictions in the Vema Fracture Zone (VFZ) with visual surveys at six locations using a towed deep-sea camera system. Exposed rock outcrops and varied hard substrates were consistently confirmed in areas of high hard-rock exposure, while moderately predicted areas contained a mix of sediments, cobbles, and pebbles; low-potential sites were almost entirely covered in sediment. Although a detailed quantification is beyond the scope of this report, visual correspondence supports the reliability of hydroacoustic predictions for abyssal habitats. Notably, this study pioneers the application of hydroacoustic-based seafloor characterization at abyssal depths—extending methods formerly focused on bathyal zones to the planet’s largest benthic environment and enabling direct ground-truthing of habitat models below 5,000 m. These findings highlight abyssal habitat heterogeneity, confirm the utility of hydroacoustic tools for broad-scale benthic mapping, and establish a baseline for future research on deep-sea biodiversity and ecological dynamics
Tectonic modulation of caldera volcanism on the South Aegean Volcanic Arc
No full textHighlights
• Caldera volcanism is associated with rifting on the South Aegean Volcanic Arc.
• We integrate drill core and seismic records of volcanism and lithospheric rifting.
• The rift basins NE of Santorini acted as depocenters for eruption-fed megabeds.
• Rapid rifting preceded a transition to highly explosive activity at Santorini.
• Tectonic stresses amplified the normal internal processes of the volcano.
• Santorini and Kos Volcanoes may be coupled by regional lithospheric stresses.
Abstract
Many highly hazardous, caldera-forming explosive eruptions occur in extensional tectonic regimes, but the role of lithospheric rifting in modulating caldera volcanism remains enigmatic. IODP Expedition 398 deep-drilled the volcano-sedimentary infills of submarine half-grabens around Santorini caldera on the continental South Aegean Volcanic Arc. Here we use the volcanic tephra archives to produce a high-resolution eruptive chronostratigraphy for Santorini, to ground-truth seismic stratigraphy, and to extract an integrated timeline of volcano-tectonic couplings. The rift basins contain several submarine volcaniclastic megabeds from the caldera-forming eruptions of Santorini and one from the Kos caldera. The thickest megabed succession is < 250,000 yrs old and lies on a seismic reflection onlap surface that records a phase of rapid rifting. Sedimentation lagged behind subsidence during this rifting phase, creating bathymetric troughs. Integrating submarine core-seismic and onland datasets, we propose that rifting may have driven the transition of Santorini from a prolonged state of effusive and minor explosive activity (∼550 – 250 ka) typical of arc stratovolcanoes to one of repeated caldera-forming eruptions (<250 ka). Rapid rifting may have amplified the normal internal dynamics of the magmatic system in three ways, driving the volcano into a sustained, highly explosive state: (1) an increase in the supply of mantle-derived basalt, (2) enhanced shearing, permeability, and melt percolation in the transcrustal magmatic system, and (3) the development of horizontally extensive magma reservoirs. Broadly simultaneous transitions into caldera-forming activity of the widely separated Santorini and Kos Volcanoes suggest that the two magmatic systems are linked by plate-scale lithospheric stresses
Biochemical Characteristics of the Sea Surface Microlayer in the Central Baltic Sea and Potential Signatures of Cyanobacterial Blooms
No full textThe sea surface microlayer (SML) forms the 20µm; filamentous and colonial cyanobacteria), total amino acids (TAA), particulate amino acids (PAA>20µm), and particulate combined carbohydrates (PCCHO>20µm) were enhanced in the ULW, mirroring POC>20µm and cyanobacterial biomass patterns. The significant correlation between phytoplankton >20µm biomass and POC>20µm suggests that the particulate organic carbon pool was largely cyanobacteria-derived, even in the absence of a distinct bloom. Together, our results imply that phytoplankton size structure and taxonomy exert distinct biomolecular imprints on SML chemistry in the Central Baltic Sea. The contrasting roles of filamentous/colonial cyanobacteria (proteinaceous signatures) and Synechococcus (carbohydrate/surface-activity imprint) imply community-dependent modulation of surface activity and, indicate that changes in biodiversity may potentially impact air–sea gas exchange in the ocean
Simulated Earth system response to acid downwelling as a form of ocean alkalinity enhancement
No full text“Acid downwelling” is a proposed marine CDR method, which describes the idea of electrochemically splitting open ocean surface water into an alkaline solution to remain at the surface ocean and cause additional ocean CO2 uptake, and into an acidic solution that is pumped down into the deep ocean for disposal via vertical pipes. In this study, we simulate idealised large-scale acid downwelling in an Earth system model of intermediate complexity with different acid injection depths and downwelling intensities and find a maximum mCDR potential for continuous acid downwelling (0.25 Pmol yr-1) of 320 Pg C until the end of the millennium under an extended RCP 4.5 CO2 emissions scenario. However, the acidity temporarily stored at depth resurfaces primarily around the Southern Ocean via ocean circulation and causes regional CO2 outgassing. Furthermore, too intense downwelling of warm surface water leads to an increase in ocean interior temperatures causing further Earth system feedbacks and accelerates the re-emergence of downwelled acidity to the surface. However, the extent to which this re-emergence causes CO2 outgassing into the atmosphere is emissions scenario dependent. This study highlights that large-scale ocean circulation, the investigated time frame and the future CO2 emission scenario all need to be considered in order to determine the mCDR potential of acid downwelling.
Key Points:
● Acid downwelling has lower long term mCDR potential compared to standard OAE
● Idealised global injection of acidic water into the ocean interior resurfaces primarily
around the Southern Ocean and offsets additional ocean carbon uptake from surface
OAE.
● Enhanced downwelling to dilute acid injection streams directly influences ocean density
structure through redistribution of salinity and heat