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Evolving and Sustaining an Ocean Best Practices System - a Continuing Evolution
No full textA decade ago, the need for a sustained, global system for best practices was identified through work in the AtlantOs and the Ocean Data Interoperability Platform (ODIP) projects, to address the global challenge to make ocean observations, data management, modeling, and applications more comprehensive and coherent on regional and global scales. In collaboration with, and building on the Repository of the Ocean Data Standards Project of the UNESCO Intergovernmental Oceanographic Commission (IOC) International Oceanographic Data and Information Exchange (IODE), in 2019, the Ocean Best Practices System (OBPS) was adopted as a project by UNESCO-IOC with the sponsorship of IODE and the Global Ocean Observation System (GOOS). The OBPS initially focused on ocean observations and data management and included a repository, a peer-reviewed journal, and capacity building element. There have been additional components, and activities facilitated by OBPS over the last five years, many of which involve community engagement and cultural changes alongside building a repository technology representing methodological documentation supporting the entire ocean information value chain
Invariable nickel dynamics in the Peru, Benguela and Mauritania oxygen minimum zones
No full textNickel (Ni) is a bio-essential trace metal used in urease, hydrogenase and superoxide dismutase enzymes. The concentration of dissolved (<0.2 μm) Ni (dNi) in the surface ocean is rarely depleted below ∼2 nM globally. This is in stark contrast to the concentrations of many other bio-essential trace metals such as iron (Fe), cobalt (Co) and manganese (Mn). Both complexation with strong ligands, potentially rendering dNi unavailable to marine organisms, and slow depletion of dNi because of low cellular demand compared to other trace metals have been invoked to explain this peculiar elemental distribution. Here we report new measurements of pelagic dNi concentrations (n = 1094) from four cruises (M135-M138) in the Eastern Tropical South Pacific (ETSP) to evaluate dNi dynamics under variable biogeochemical conditions in a highly productive shelf region. We additionally report total and labile particulate Ni concentrations along two cross-shelf sections at 16° S and 17° S. The ETSP features a productive Eastern Boundary Upwelling System along the Peruvian-Chilean shelf. This coincides with an extensive underlying Oxygen Minimum Zone which leads to persistently high phosphate and intermittently high Fe conditions.
The vast majority of dNi concentrations measured across the Peruvian shelf were within the range 2.2–10.8 nM dNi with highly reproducible depth profiles compared to prior cruises in different seasons, years, and El Niño–Southern Oscillation phases. Evidence of lower dNi concentrations was only found at one inshore location with dNi as low as 1.3 nM. Such low dNi concentrations appear to be rare. Whilst biogenic Ni associated with diatom detritus is buried in Peruvian shelf sediments, biological dNi demand on the Peruvian shelf is <30 % of the annual upwelled dNi flux and burial in shelf sediments accounts for approximately 1–3 % of the upwelled dNi flux. Total particulate Ni concentrations measured on two cross-shelf sections ranged from below detection to 1.2 nM and were consistently low relative to dNi concentrations. On average, total particulate Ni (TpNi) was 2.6 % of dNi + TpNi with labile particulate Ni (LpNi) and TpNi remaining tightly coupled (R2 = 0.99). As is the case elsewhere in the global ocean, dNi remained tightly correlated with phosphate and silicic acid concentrations. Limited biological demand for Ni relative to the upwelled dNi supply explains why dNi profiles in general were quite homogenous across the Peruvian coastal, shelf and offshore regions. Finally, profiles of dNi suggested a slightly lower than average dNi:phosphorous ratio (0.673 mmol (mol P)−1) in the upper water column. Similar distributions of dNi and dNi:phosphorous ratios were found for the Benguela and Mauritania shelves reinforcing the relatively invariable nature of dNi profiles even in extremely productive shelf environments
South Asian Monsoon climate control of Neogene to Pleistocene silicate weathering
No full textThe weathering of silicate rocks removes CO2 from the atmosphere-ocean system on geological timescales but where exactly these reactions occur and the role of the monsoon climate is poorly constrained. Here we examine the coupled Nd-Hf isotope signatures of clays deposited along the Ganges River sediment cascade by comparing a core from the floodplain, surface sediment samples from the Bay of Bengal shelf, and a marine sediment core from near the mouth of the Ganga-Brahmaputra. For a longer-term perspective of the evolution of silicate weathering under the monsoon climate, samples from International Ocean Discovery Program Site U1443 were measured at orbital resolution across the middle Miocene. The radiogenic isotopes of hafnium and neodymium are decoupled during silicate weathering with deviations of clay Hf isotope compositions from the global average (ΔεHf clay) reflecting silicate weathering intensity. The middle Miocene sediments exhibit some of the highest ΔεHf clay values measured to date suggesting the prevalence of extremely intense chemical weathering during the mid-Miocene climatic optimum. The ΔεHf clay values decrease during the late Miocene, signalling a decrease in weathering intensity and monsoon precipitation. Pleistocene ΔεHf clay values from both terrestrial and marine sediment cores display a temporal pattern of variability similar to the record of South Asian Monsoon intensity inferred from seawater d18O and dD of leaf waxes from the marine core. This demonstrates a strong link between hydroclimate and silicate weathering across this region, where monsoon seasonality and intensity, erodes and delivers a large proportion of sediments to the oceans
Biogeochemical Shifts During Arctic Spring: Surfactants in the Sea-Surface Microlayer Reduce CH 4 and N 2 O Emissions During the Onset of Sea Ice Melt
No full textThe sea-surface microlayer (SML) is the less than one millimeter thin interface between the surface ocean and the overlying atmosphere and plays a crucial role in sea-air gas exchange processes. However, its role for sea-air exchange processes in sea ice-influenced environments such as the Arctic Ocean remains poorly understood. Here, we present the first in situ measurements of surfactants accumulating in the SML of the Fram Strait, coupled with near-surface measurements of the climate-relevant trace gases CH4 and N2O. Sampling of the undisturbed surface ocean was conducted at leads and ice holes during the onset of sea ice melt and an early algal bloom between May and June 2023. Our results reveal that the region acted as a minor source of CH4 and N2O. Nonetheless, the algal bloom stimulated the production of surfactants, which accumulated in the SML of open leads, reducing the emissions of CH4 and N2O to the atmosphere. These findings highlight the importance of resolving short-term surface processes during seasonal transitions and of integrating SML dynamics into investigating trace gas fluxes in polar regions
Absolute abundance unveils Basidiobolus as a cross-domain bridge indirectly bolstering gut microbiome homeostasis
No full textThe host microbiome is integral to metabolism, immune function, and pathogen resistance. Yet, reliance on relative abundance in microbiome studies introduces compositional biases that obscure ecological interpretation, while the absence of robust tools for absolute abundance quantification has limited biological discovery. Here, we apply absolute abundance profiling to uncover host-specific microbial patterns across herpetofauna orders that are masked in relative abundance data. Relative- and absolute abundance-derived bacterial and fungal microbiomes exhibit divergent profiles shaped by compositional bias and multifactorial effects. Absolute abundance identified key genera, Lactococcus, Parabacteroides, and Cetobacterium in salamanders, and Basidiobolus and Mortierella in lizards, turtles, snakes, and tortoises, that consistently emerged as core taxa, revealing host-associated patterns previously obscured by compositional constraints. In closely related Desmognathus species, where environmental and phylogenetic variation was minimized, absolute abundance enabled finer resolution of microbiome dynamics and significantly reduced false discovery rates. Absolute abundance-based network analyses further revealed distinct keystone taxa between the relative and absolute abundance datasets. Despite low redundancy, Basidiobolus exhibited high network betweenness, efficiency, and degree, suggesting its role as a key connector between microbial modules and a contributor to overall network robustness. This predicted structural role aligns with Burt's structural hole theory, which suggests that nodes linking otherwise disconnected modules occupy influential network positions. These findings underscore the value of absolute abundance in resolving microbial dynamics and supporting meaningful interpretation of host-microbiome associations. This advance is made possible by DspikeIn, a flexible wet-lab and computational framework that enhances ecological resolution and cross-study comparability
Horizontal distribution of mesozooplankton biomass and size spectra along the Amazon River plume continuum during the mesoscale North Brazil current retroflection
No full textThe Amazon River plume (ARP) and the North Brazil Current Retroflection (NBCR) influence the complex dynamics of the Western Tropical Atlantic (WTA), increasing biological productivity. This study estimated the spatial mesozooplankton distribution, community composition, horizontal carbon transport and normalized biovolume size spectra (NBSS) in different WTA current sectors, focusing on the ARP influence. To this end, oblique zooplankton bongo samples (300 μm) were obtained in October 2012 and analyzed using a ZooScan. Environmental conditions and current sectors were defined by in situ Conductivity, Temperature, Depth (CTD) sensor and Acoustic Doppler Current Profiler (ADCP) measurements. Zooplankton abundance and biovolume were highest in ARP-influenced areas, particularly near the shelf break and within the NBCR region. The ARP influence led to steeper NBSS slopes (more small-sized and fewer large-sized organisms). Horizontal carbon transport among all sectors was highest in the NBCR (93.54 ± 173.57 ktC/d), 22 times larger than the values recorded at the Amazonian continental shelf, indicating substantial transport from coastal to oceanic regions. No differences in trophic efficiency were observed across the WTA, attributed to the ARP impact on large organism abundance and community composition. This study highlights the crucial role of the ARP-NBCR system in seasonal zooplankton productivity enhancement and substantial coastal–oceanic carbon transport in the WTA
Wunderwelt Seegraswiesen
No full textSeegras speichert nicht nur die größten Zuckervorräte unseres Planeten- diese Pflanze schützt weltweit die Strände vor Erosion und ist mit ihren fast 80.000 Jahre alten Wiesen das vielleicht älteste Lebewesen der Erde. Seegras reinigt das Meerwasser wie eine gigantische Kläranlage. Die Doku begleitet führende Seegrasforscher*innen vom Mittelmeer bis an die Ostsee.
Filmgespräch im Anschluss in der Kinobar mit Forschungstaucher und Protagonist Dr. Philipp Schubert vom GEOMAR HelmholtzZentrum für Ozeanforschung Kie
Bericht zur Kurzfahrt: Gerätetest von BGR Tiefseegeräten mit FS ALKOR 29-25
No full textZeitraum: 23.09.2025, 08:00 bis 24.09.2025, 15:00
Zielsetzung: Im Rahmen der zweitägigen Expedition mit FS Alkor wurden neue geophysikalische Geräte und Messverfahren getestet und für zukünftige Schelf- und Tiefseeexpeditionen vorbereitet. Dafür wurde erstmals eine CSEM Messkette aus mehreren, neuentwickelten "SPOCK" (dreiaxialen) E-Feld Empfängern der BGR, mit online Datenanzeige im Labor, gemeinsam mit einer elektromagnetischen Quelle geschleppt und Untergrundstrukturen in der Eckernförder Bucht vermessen. Ziel war u.a. den Depressor (SPECTRE) und die ca. 200 m lange Messkette aus Dipolsender und zwei SPOCKS in einer kontrollierten Tiefenlage mit online-Datenanzeige zu schleppen und Messdaten mit möglichst optimaler Datenqualität zu erfassen
