The ecology of live bathyal benthic foraminifera on the southern and southeastern Australian Margin
Living (Rose Bengal stained) benthic foraminifera were examined in multicore samples collected at depths ranging from 580 to 1,270 m from the Tasman Sea and southern margin of Australia. This study presents an initial overview of the deep-sea foraminifera living on these margins. Based on widely separated cores, there appears to be no correlation between foraminiferal abundance and species with ocean depth, seafloor grain size, oxygen availability, temperature, or particulate organic carbon. Although more work is needed, this study suggests environmental factors affect foraminiferal populations in a complex manner in the study area. The presence of species typical of shelf and shallow water environments in cores collected below 200 m water depth suggests a possible redistribution from shallower areas. In the ten samples from the 0–1 cm interval for the >150 ?m size fraction, 37 unique species were found. No more than four species overlapped across sites. Surprisingly, no significant correlations were observed between cosmopolitan foraminifera (i.e., Cibicidoides bradyi, Cibicidoides mundulus, Globobulimina subglobosa, Hoeglundina elegans, Uvigerina asperula, and Melonis affinis) and environmental parameters. Considerable environmental heterogeneity between sample sites, such as oxygen availability, grain size, and other factors associated with ocean circulation, is clearly evident. Based on observed assemblages, foraminiferal populations in the region appear influenced by dynamic and heterogeneous seafloor environments. This study serves as one of the few investigations of its kind to examine the ecology and diversity of contemporary deep-sea benthic foraminiferal communities along the southern and southeastern Australian margin, and highlights the potential ecological impacts of the heterogeneity and complexity of seafloor environments in the region. Additional work is necessary to further test and evaluate these hypotheses, and this research provides a foundation for future observations of living benthic foraminifera in the region.
(Micropaleontology. vol. 71, n° 0026-2803, pp. 307-334, 01/07/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, RSES, ANU
Integrative taxonomy reveals further hidden diversity of Marphysa (Polychaeta: Eunicidae) in European Atlantic and Mediterranean waters
Abstract Marphysa (Polychaeta: Eunicidae) is represented in the Mediterranean by M. aegypti, M. birgeri, and M. chirigota. Previous reports of M. sanguinea are doubtful, because it has a confirmed distribution around the southern English coasts (NE European Atlantic). In this study, we combine morphological and molecular (using 16S rDNA and cytochrome c oxidase I) analyses to reveal for the first time the presence of M. gaditana in the NW Mediterranean (Gulf of Tunis, Tunisia) and to substantiate its presence along the Atlantic coasts of France—previously relying solely on molecular data—drawing on specimens collected in Arcachon Bay and Oléron Island. Our findings also allow us to describe a new species of Marphysa from the Mediterranean coasts of southern France, namely Marphysa gili Martin and Romano, sp. nov., based only on morphological data. Our research highlights previously overlooked diversity within Marphysa on Atlantic and Mediterranean European coasts, thus contributing to the growing series of recent rigorous taxonomic studies that are challenging the historical tendency to merely report ‘M. sanguinea’ without a thorough taxonomic examination or when undertaking physiological, reproductive, or resource management studies on ‘M. sanguinea’ without questioning the appropriateness of using this species’ name.
(Zoological Journal of the Linnean Society. vol. 204, n° 0024-4082, 01/07/2025)
CEAB, CSIC, UTM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, LIENSs, INSU - CNRS, ULR, CNRS, OBIONE, LIENSs, INSU - CNRS, ULR, CNRS
A Weakened AMOC Could Cause Southern Ocean Temperature and Sea‐Ice Change on Multidecadal Timescales
We present the first CMIP6-era multi-model intercomparison of the Southern Ocean (SO) temperature and sea-ice response to substantial Atlantic meridional overturning circulation (AMOC) weakening. Results are based on analysis of the North Atlantic Hosing Model Intercomparison Project, involving eight CMIP6 models under identical North Atlantic freshwater hosing. On multidecadal timescales, we find that southwards ocean heat transport into the SO increases, causing surface warming and sea-ice loss. Additionally, an atmospheric tropical-Antarctic teleconnection, identified here for the first time, causes regional temperature and sea-ice changes in the SO. Unlike previous studies, we find that the Amundsen Sea Low deepens for only some models. Overall, in the multi-model ensemble mean (multi-model range in brackets), over years 50-100 after AMOC weakening: SO surface air temperature warms by 0.3 (0.1-0.7)°C, sea level pressure (SLP) decreases by 30 (10-70) Pa, and sea-ice area decreases by 0.4 ( 0.2-1.3) Mkm 2 . The teleconnection leads to regional differences between the response in the Indian sector and the Weddell Sea of 180 (80-320) Pa in SLP, 0.6 (0.5-1.4)°C in surface air temperature, and 0.1 (0.1-0.2) Mkm 2 in sea-ice area. These SO heat transport, temperature, pressure, and sea-ice changes are small relative to the changes expected under future anthropogenic warming, despite the large and idealized 0.3 Sv hosing used to weaken the AMOC.
(Journal of Geophysical Research. Oceans. vol. 130, n° 2169-9275, pp. e2024JC022027, 01/07/2025)
CAM, UOR, BAS, NERC, NCAR, MPI-M, UCM, CCCma, ECCC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Drivers of Water Mass Volume Changes in the Nordic Seas (2005–2020)
The Nordic Seas are integral parts of the Atlantic meridional overturning circulation and a key region for the global climate. In this study, we combine observational products, largely derived from the Argo array, to examine the changes affecting ocean conditions in the different regions of the Nordic Seas from 2005 to 2020. Significant warming and deepening of isopycnal surfaces have been found across all regions since 2013, resulting in a volume increase of the surface layer above the σ0 < 27.8 kg m−3 isopycnal. A volume budget over three isopycnal layers is built to disentangle the relative roles played by the atmospheric forcing that results in local water mass transformation and large‐scale advection. In eastern basins, an increase in both the advection of Atlantic water and surface water mass transformation led to an expansion of the surface layer after 2012. In contrast, changes found in the Greenland Sea result primarily from a decrease in transport convergence and changes in the surface forcing that ventilates all layers of the region. Our analysis also highlights that an improved sampling of the region, including toward greater depths and on the East Greenland shelves, is required to reduce uncertainties in the water mass transformation budget of the Nordic Seas and to better understand the mechanisms at play.
(Journal of Geophysical Research. Oceans. vol. 130, n° 2169-9275, pp. e2024JC022209 (16p.), 01/07/2025)
LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Near Steady Late Pleistocene Tropical Denudation Rates in SW Madagascar
Denudation is a key parameter controlling the evolution of the Earth's surface, the production of soils, the stability of relief, or the long‐term evolution of climate. Climate fluctuations conversely have a strong impact on denudation, but these complex feedback mechanisms are still under‐constrained. To better predict future changes that will affect our habitat and understand the links between climate and denudation, precise quantification of paleo‐denudation rates is required. In this work, we measure cosmogenic radionuclides (10Be) in turbidites of a well‐dated marine sedimentary core recovered in the Mozambique Channel to provide a 900‐ka long near‐continuous record of paleo‐denudation rates over the 100‐ka climatic cycles. Neodymium isotopes and heavy mineral analysis were used to provide constraints on the provenance of terrigenous sediments exported from Madagascar to the studied site and show that temporal variations in sediment provenance are limited and decoupled from climatic cyclicity. Our 10Be‐based paleo‐denudation rates are in the same order as modern rates, ranging from 17.4 ± 5.8 mm/ka to 73.9 ± 29.4 mm/ka (1 standard deviation), and do not show major variations through the Middle and Late Pleistocene. Importantly, we did not identify a systematic significant impact of glacial/interglacial cyclicity on denudation rates. Denudation of this subtropical island may instead have been controlled by variability of monsoon intensity associated with shifts in the Inter Tropical Convergence Zone, but this interpretation remains speculative at this stage as it cannot be recorded within the resolution of cosmogenic‐derived denudation rates.
(Journal of Geophysical Research: Earth Surface. vol. 130, n° 2169-9003, pp. e2024JF008147 (32p.), 01/07/2025)
CRPG, INSU - CNRS, UL, CNRS, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, UNIMIB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Measuring Ocean Surface Waves
Propagating waves on the surface of the ocean can be represented as a stochastic process, whose statistics are characterized by a spectrum. Measuring the wave spectrum, and quantities derived from the spectrum, are reviewed here. Observation begins by sensing some property of the sea surface over space and/or time. Visual observations, collected routinely since the mid 18th century, comprise the longerest running wave record. Measurement methods in the nearshore are advancing, including traditional methods using pressure and acoustic sensing, but also newer methods such as distributed acoustic sensing and lidar. Detailed, small scale wave physics can now be explored with measurement techniques using light, including stereo-imaging and polarimatry. The decrease in size, cost, and power consumption of microelectronics has propagated through to ocean wave instrumentation, most notably in wave buoys. Global networks of freely drifting miniature wave buoys offer novel observational power. Remote sensing techniques based on radar and lidar continue to evolve, and are widely deployed from land and on ships, aircraft, autonomous vehicles, and satellites. Spaceborne altimeters form one of the most important records of wave height, and a suite of suite of new spaceborne sensors are observing directional spectra across the globe with sampling akin to traditional altimetry. Aircraft and autonomous systems are providing strategic sampling capabilities, whether for detailed process studies or accessing extreme storm environments. The quality and quantity of ocean wave measurements has never been greater. This review will help you make sense of it all.
(30/06/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS
Contaminant storage in depositional environments induced by river engineering in the upper Seine Estuary (France)
The extensive engineering of the Seine estuary upstream of Rouen (France) since the 1950s to support the growth of river transport has led to a significant recalibration of the riverbed. These morphological changes have enhanced sedimentation in sheltered areas, which are known to trap contaminants from upstream anthropized watersheds. As part of the DESTOX project, five depositional environments, constructed between 1953 and 1981, and each of them storing up to 1.105 m3 of sediment, are being investigated. Ten sediment cores were collected from a mudflat embanked in 1972. Concentrations of PAHs, PCBs, alkanes, metals and 137Cs activities are being measured along one of the cores (1.62 m). PAH concentrations will be estimated on the 9 other cores using hyperspectral imaging (following the method from Jacq et al., 2024) and interpolated to assess the PAH stock at the site scale. Preliminary results show PCB concentrations of up to 3.9 ± 0.4 mg kg-1, which is 50 times higher than the average concentration measured in suspended particulate matters currently circulating in the Seine Estuary. The aim of this work is to measure the extent of contamination in sediment stocks in the upper estuary in order to better understand the potential risk associated with the remobilization of these sediments. Such remobilization could be triggered by extreme hydrological events, restoration work, sea-level rise or other processes.
(30/06/2025)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GIP-Seine-Aval, Cerema, LEHNA, UCBL, ENTPE, CNRS
Chronostratigraphy of the mixed Upper Cretaceous deposits at the northern margin of the Arabian Plate (Jordan)
This study provides an updated chronostratigraphy to the biozone level, integrating nannofossils, ammonites, benthic foraminifera, and Sr isotopes, for the mixed carbonate-siliciclastic-phosphatic-organic-rich Upper Cretaceous succession in south-central Jordan based on two well-exposed sections of 635 m and 712 m thick and located 100 km apart. Seven stratigraphic hiatuses have been identified, and significant changes in sedimentation rate are observed for this lithologically diverse stratigraphic succession. Well-dated surfaces are identified and provide unique and high-resolution calibration points for tectonic and paleoceanographically induced sedimentary system changes affecting the southeastern Neo-Tethys margin. The studied sections are located on the northern Arabian Plate continental shelf and contain a rich calcareous nannofossil assemblage that increases upwards in abundance and diversity. Ammonoids and benthic foraminifera helped to refine the Cenomanian and Turonian shallow water carbonate interval of the Ajlun Group. In the overlying Belqa Group, the integration of 87Sr/86Sr dating provided essential age constraints for the fossil barren shallow-water siliciclastic deposits of the Coniacian and Santonian, while it also provided calibration points for the nannofossil-rich Campanian and Maastrichtian strata. Age-depth and Bayesian statistics modeling constrain the duration and positions of the stratigraphic hiatuses, which show a consistent pattern between the 100 km spaced sections and have been correlated to the neighboring countries.
(Newsletters on Stratigraphy. vol. 58, n° 0078-0421, pp. 161-201, 21/06/2025)
KAUST, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BGS
Elucidation of the life cycle of the trematode Curtuteria arguinae (Digenea: Himasthlidae), using environmental DNA detection methods
Abstract Detection approaches based on environmental DNA (eDNA) are widely used for free-living species but remain underutilized for parasite species. This study applies eDNA detection methods to elucidate the life cycle of the trematode Curtuteria arguinae , which infects the socioeconomically and ecologically important edible cockle ( Cerastoderma edule ) as its second intermediate host along the northeastern Atlantic coast, including Arcachon Bay, France. The first intermediate and definitive hosts remained unknown. To identify these hosts – presumed to be a gastropod and a shorebird – we developed a quantitative PCR (qPCR)-based eDNA approach targeting partial cox1 and SSU gene regions of C. arguinae . We tested for C. arguinae eDNA presence in water samples containing separately five dominant gastropod species and fecal samples from known cockle predators, the European oystercatcher ( Haematopus ostralegus ) and gulls ( Larus spp.), collected in Arcachon Bay. C. arguinae eDNA was only detected in water containing the needle snail ( Bittium reticulatum ), with cercarial emergence confirming infection in 1.6% of individual hosts. Morphological analysis of the cercarial and metacercarial stages revealed variability in collar spine visibility. Additionally, C. arguinae was detected by qPCR in 42% of oystercatcher feces and no gull feces, suggesting oystercatchers are the definitive host. This study is the first to elucidate the complete life cycle of C. arguinae , identifying B. reticulatum as its first intermediate host and H. ostralegus as its definitive host. Our findings highlight the potential of eDNA approaches for resolving parasite life cycles and enabling advances in ecological research on C. arguinae .
(Parasitology. vol. 152, n° 0031-1820, pp. 704-714, 18/06/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOMAP, AD2M, CNRS, SBR, SU, CNRS, SBR, SU, CNRS, AD2M, SBR, UPMC, CNRS, UPMC, CNRS, IRSTEA
An extreme drought and heatwave event led to collapse of facilitation by metallophyte species in metalliferous ecosystems
Aims: Recent studies have highlighted the importance of plant facilitation in metal-rich environments. Among the positive effects of metallophyte nurse plants, the improvement of microclimatic conditions for neighboring plants has been reported. Here, we aim to assess if plant facilitation persists with the additional stress caused by the extreme drought and heatwave that occurred in 2022 in the northern hemisphere. Methods: We conducted four transplant experiments with grass species placing them under nurse plants or in areas where nurse plants have been removed. These experiments were carried out along soil pollution gradients at various sites and elevation in a former mining valley in the French Pyrenees. The first three experiments were conducted in 2020 and 2021, while the fourth was done in 2022. Each year, transplant survival was monitored at the end of the growing season. Results: The 2020 and 2021 experiments confirmed the increase of positive interactions as metal-pollution increased, aligning with the Stress Gradient Hypothesis. However, during the extreme year, facilitation disappeared, likely because dominant nurse plants were weakened and no longer influenced neighboring plants. Conclusions: Metallophyte species in temperate regions are not necessarily drought-tolerant and are certainly affected by severe drought and heatwaves. This additional intense stress, in habitats already challenged by metal presence in soils, likely compromised their ability to improve micro-climatic conditions for neighboring plants. This collapse of facilitative effects was observed at both low- and high-elevation sites, highlighting the strong impact of such meteorological event in metalliferous ecosystems.
(Plant and Soil, n° 0032-079X, 12/06/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, UMR ISPA, Bordeaux Sciences Agro, INRAE