Technical note: Assessment of float pH data quality control methods – a case study in the subpolar northwest Atlantic Ocean

Since a pH sensor has become available that is principally suitable for use on demanding autonomous measurement platforms, the marine CO2 system can be observed independently and continuously by Biogeochemical Argo floats. This opens the potential to detect variability and long-term changes in interior ocean inorganic carbon storage and quantify the ocean sink for atmospheric CO2. In combination with a second parameter of the marine CO2 system, pH can be a useful tool to derive the surface ocean CO2 partial pressure (pCO2). The large spatiotemporal variability in the marine CO2 system requires sustained observations to decipher trends and study the impacts of short-term events (e.g., eddies, storms, phytoplankton blooms) but also puts a high emphasis on the quality control of float-based pH measurements. In consequence, a consistent and rigorous quality control procedure is being established to correct sensor offsets or drifts as the interpretation of changes depends on accurate data. By applying current standardized routines of the Argo data management to pH measurements from a pH / O2 float pilot array in the subpolar North Atlantic Ocean, we assess the uncertainties and lack of objective criteria associated with the standardized routines, notably the choice of the reference method for the pH correction (CANYON-B, LIR-pH, ESPER-NN, and ESPER-LIR) and the reference depth for this adjustment. For the studied float array, significant differences ranging between ca. 0.003 pH units and ca. 0.04 pH units are observed between the four reference methods which have been proposed to correct float pH data. Through comparison against discrete and underway pH data from other platforms, an assessment of the adjusted float pH data quality is presented. The results point out noticeable discrepancies near the surface of > 0.004 pH units. In the context of converting surface ocean pH measurements into pCO2 data for the purpose of deriving air–sea CO2 fluxes, we conclude that an accuracy requirement of 0.01 pH units (equivalent to a pCO2 accuracy of 10 µatm as a minimum requirement for potential future inclusion in the Surface Ocean CO2 Atlas, SOCAT, database) is not systematically achieved in the upper ocean. While the limited dataset and regional focus of our study do not allow for firm conclusions, the evidence presented still calls for the inclusion of an additional independent pH reference in the surface ocean in the quality control routines. We therefore propose a way forward to enhance the float pH quality control procedure. In our analysis, the current philosophy of pH data correction against climatological reference data at one single depth in the deep ocean appears insufficient to assure adequate data quality in the surface ocean. Ideally, an additional reference point should be taken at or near the surface where the resulting pCO2 data are of the highest importance to monitor the air–sea exchange of CO2 and would have the potential to very significantly augment the impact of the current observation network

Preliminary Characterization of Submarine Basalt Magnetic Mineralogy Using Amplitude‐Dependence of Magnetic Susceptibility

The past ∼200 million years of Earth's geomagnetic field behavior have been recorded within oceanic basalts, many of which are only accessible via scientific ocean drilling. Obtaining the best possible paleomagnetic measurements from such valuable samples requires an a priori understanding of their magnetic mineralogies when choosing the most appropriate protocol for stepwise demagnetization experiments (either alternating field or thermal). Here, we present a quick, and non‐destructive method that utilizes the amplitude‐dependence of magnetic susceptibility to screen submarine basalts prior to choosing a demagnetization protocol, whenever conducting a pilot study or other detailed rock‐magnetic characterization is not possible. We demonstrate this method using samples acquired during International Ocean Discovery Program Expedition 391. Our approach is rooted in the observation that amplitude‐dependent magnetic susceptibility is observed in basalt samples whose dominant magnetic carrier is multidomain titanomagnetite (∼TM 60–65 , (Ti 0.60–0.65 Fe 0.35–0.40 )Fe 2 O 4 ). Samples with low Ti contents within titanomagnetite or samples that have experienced a high degree of oxidative weathering do not display appreciable amplitude dependence. Due to their low Curie temperatures, basalts that possess amplitude‐dependence should ideally be demagnetized either using alternating fields or via finely‐spaced thermal demagnetization heating steps below 300°C. Our screening method can enhance the success rate of paleomagnetic studies of oceanic basalt samples. Plain Language Summary Oceanic basalts are ideal recorders of the Earth's magnetic field. To decipher magnetic histories recorded in rocks, paleomagnetists need to isolate the magnetization directions and intensities within rocks by one of two possible methods. One method typically involves progressively heating the samples to high temperatures. The other method involves exposing samples to alternating magnetic fields with increasing peak field intensities. Both of these methods are ultimately destructive to the original magnetization preserved within rocks. However, without knowledge of a given rock's magnetic mineralogy, randomly choosing thermal or alternating field demagnetization methods may result in high failure rates. We developed a pre‐screening method to help decide which cleaning method will likely be more successful for a given sample based on low‐field magnetic susceptibility measurements. These measurements do not affect the original magnetic information recorded in a rock, thereby permitting subsequent paleomagnetic studies on the same sample. Our technique can be performed as rapidly as 2 min per sample, is non‐destructive, and does not require complicated sample preparation. Key Points Paleomagnetic studies utilize either alternating field or thermal demagnetization, but it is difficult to choose the best protocol a priori Amplitude‐dependence of magnetic susceptibility measurements permits preliminary magnetic mineralogy characterization in submarine basalts Rapid amplitude‐dependence measurements may aid in deciding upon the best demagnetization protocol for submarine basalt sample

A comparison of the atmospheric response to the Weddell Sea Polynya in atmospheric general circulation models (AGCMs) of varying resolutions

The Weddell Sea Polynya (WSP) is a large opening within the sea ice cover of the Weddell Sea sector. It has been a rare event in the satellite period, appearing between 1973 and 1976 and again in 2016/2017. Coupled modelling studies have suggested that there may be a large-scale atmospheric response to the WSP. Here, the direct atmospheric response to the WSP is estimated from atmosphere-only numerical experiments. Three different models, the HadGEM3 UK Met Office model, the ECHAM5 Max Planck Institute model, and the OpenIFS ECMWF model, each at two different resolutions, are used to test the robustness of our results. The use of large ensembles reduces the weather variability and isolates the atmospheric response. Results show a large (∼100-200 Wm-2) turbulent air-sea flux anomaly above the polynya. The response to the WSP is local and of short duration (barely outlasting the WSP) with a similar magnitude and spatial pattern of lower-tropospheric warming and increase in precipitation in all six configurations. All models show a weak decrease in surface pressure over the WSP, but this response is small (∼2 hPa) in comparison to internal variability. The dynamic response is inconsistent between models and resolutions above the boundary layer, suggesting a weak or null response that is covered by internal variability aloft. The higher resolution does not alter the pattern of the response but increases its magnitude by up ∼50% in two of the three models. The response is influenced by natural variability in the westerly jet. The models perform well against ERA5 reanalysis data for the 1974 WSP in spatial response and magnitude, showing a turbulent heat flux of approximately 150 W m-2

Whales and cephalopods in a deep‐sea arms race

Scientific Significance Statement Millions of predator–prey interactions between deep-diving toothed whales and cephalopods occur daily in the dark deep sea. While predatory whales developed traits to detect and hunt their prey, cephalopods had to expand their anti-predatory strategies specialized for visual predators, to counteract acoustic predators. Since toothed whale-cephalopod interactions have never been directly observed in the deep sea, it remains unknown what selective pressures and traits evolved from this arms race. Combining current knowledge, we formalize four hypotheses and associated research approaches that will guide future investigation on oceanic predator–prey systems. We identify whale echolocation as an unprecedented armament to hunt distant prey and propose that deep-sea squids avoid acoustic predators by (1) reducing their acoustic cross-section through body shape and posture, (2) deep-sea migration, and (3) not schooling. Toothed whale predation emerges as a potential driver of the cephalopod live-fast-die-young strategy—which may now leave cephalopods at competitive advantage under global change

Perspektiven eines politikplanenden Biodiversitätsschutzgesetzes: Rechtsrahmen, Ausgestaltung und Forschungsbedarf

Der Biodiversitätsverlust schreitet in bedrohlichem Ausmaß voran. Mit dem Global Biodiversity Framework und voraussichtlich dem Nature Restoration Law bestehen nun auf internationaler und europäischer Ebene vielversprechende Ansätze, ihm Herr zu werden. Jetzt ist der Bundesgesetzgeber – nicht zuletzt aus verfassungsrechtlichen Erwägungen – aufgerufen, daran anzuknüpfen. Dazu bietet sich die Regelungsform eines Rahmen- und Politikplanungsgesetzes an, wie sie schon aus dem Klimaschutzgesetz und dem Klimaanpassungsgesetz bekannt ist. Der Aufsatz beleuchtet den internationalen, europa- und verfassungsrechtlichen Hintergrund eines solchen ‘Biodiversitätsschutzgesetzes’ und diskutiert – unter Zusammenarbeit sowohl rechts- als auch naturwissenschaftlicher Autor:innen – formale und materielle Ausgestaltungsmöglichkeiten

Confocal μ -XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano

Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 µm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+  ΣFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+  ΣFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite–ilmenite equilibrium shows redox conditions with Fe3+  ΣFe ≤0.20 (close to FMQ, fayalite–magnetite–quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+  ΣFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation

A comparative study of the sociotechnical imaginaries of marine geoengineering

In this report, we claim that although there is no national deployment or consultation program for OceanNETs in the US, Germany, or Australia, the very idea is sufficiently open-ended to accommodate and even federate different development pathways for industrial-scale emissions reduction. We use the “sociotechnical imaginaries” concept to show how existing moral and political outlooks can, concretely, support the more abstract “need” for OceanNETs within overshoot scenarios. Thus, even without an endorsement of the feasibility or desirability of OceanNETs—as a matter of transnational climate negotiations, for example—it is possible to observe openings for large-scale transformations in ocean use under the description of “climate action.” Such changes are patchier than the imagined research-to-deployment pipeline considered in conventional depictions of OceanNETs, and, indeed, may take the form of those techniques often deemed most marginal to the OceanNETs research agenda, such as “carbon capture and storage” or “seaweed afforestation.” Moreover, the difficulty of engaging local communities in these ongoing changes is a structural feature of negative emissions technology development more generally. This difficulty can be understood not only as a matter of geography, but of the assumptions of net-zero politics, in particular the abstraction of the global carbon budget. This exposes OceanNETs to considerable political and moral instabilities expressed in—yet not reducible to—concerns over the “hype cycle” or “rogue action.

Report on the Marine Imaging Workshop 2022

Imaging is increasingly used to capture information on the marine environment thanks to the improvements in imaging equipment, devices for carrying cameras and data storage in recent years. In that context, biologists, geologists, computer specialists and end-users must gather to discuss the methods and procedures for optimising the quality and quantity of data collected from images. The 4 th Marine Imaging Workshop was organised from 3-6 October 2022 in Brest (France) in a hybrid mode. More than a hundred participants were welcomed in person and about 80 people attended the online sessions. The workshop was organised in a single plenary session of presentations followed by discussion sessions. These were based on dynamic polls and open questions that allowed recording of the imaging community’s current and future ideas. In addition, a whole day was dedicated to practical sessions on image analysis, data standardisation and communication tools. The format of this edition allowed the participation of a wider community, including lower-income countries, early career scientists, all working on laboratory, benthic and pelagic imaging. This article summarises the topics addressed during the workshop, particularly the outcomes of the discussion sessions for future reference and to make the workshop results available to the open public

Streptomyces profundus sp. nov., a novel marine actinobacterium isolated from deep-sea sediment of Madeira Archipelago, Portugal

A novel strain, MA3_2.13T, was isolated from deep-sea sediment of Madeira Archipelago, Portugal, and characterized using a polyphasic approach. This strain produced dark brown soluble pigments, bronwish black substrate mycelia and an aerial mycelium with yellowish white spores, when grown on GYM 50SW agar. The main respiratory quinones were MK-10(H4), MK-10(H6) and MK-10(H8). Diphosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids and two glycophospholipids were identified as the main phospholipids. The major cellular fatty acids were iso-C16: 1, iso-C16: 0, anteiso-C17: 1 and anteisoC17: 0 . Phylogenetic analyses based on 16S rRNA gene showed that strain MA3_2.13T is a member of the genus Streptomyces and was most closely related to Streptomyces triticirhizae NEAU-YY642T (NR_180032.1; 16S rRNA gene similarity 97.9 %), Streptomyces sedi YIM 65188T (NR_044582.1; 16S rRNA gene similarity 97.4 %), Streptomyces mimosae 3MP-10T (NR_170412.1; 16S rRNA gene similarity 97.3 %) and Streptomyces zhaozhouensis NEAU-LZS-5T (NR_133874.1; 16S rRNA gene similarity 97.0 %). Genome pairwise comparisons with closest related type strains retrieved values below the threshold for species delineation suggesting that strain MA3_2.13T represents a new branch within the genus Streptomyces. Based on these results, strain MA3_2.13T (=DSM 115980T=LMG 33094T) is proposed as the type strain of a novel species of the genus Streptomyces, for which the name Streptomyces profundus sp. nov. is proposed

Polychaete composition from the abyssal plain adjacent to the Kuril–Kamchatka Trench with the description of a new species of Sphaerephesia (Polychaeta: Sphaerodoridae)

During the KuramBio expedition, the abyssal plain adjacent to the Kuril–Kamchatka Trench was sampled in July–August 2012. More than 5200 individuals of Polychaeta belonging to 38 families, 108 genera and about 144 species were found. Six genera have been reported for the Northwest Pacific for the first time. About 50% of the collected polychaete species are considered as new to science. One of these, Sphaerephesia lesliae sp. n., is described herein. The detailed description of the new species is presented and its differences from similar species are shown. This eighth species of the genus is characterized by the presence of macrotubercles with two paired terminal papillae. The genus Sphaerephesia Fauchald, 1972 is newly recorded in the Northwest Pacific. An updated key to the species of the genus Sphaerephesia is provided