What drives the millennial and orbital variations of δ18Oatm?
(Quaternary Science Reviews. vol. 29, n° 0277-3791, pp. 235-246, 01/01/2010)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIBE, ITU
Seasonal progression of diatom assemblages in surface waters of Ryder Bay, Antarctica
Phytoplankton assemblages from seasonally sea-ice covered Ryder Bay (Adelaide Island, Antarctica) were studied over three austral summers (2004-2007), to link sea-ice variability and environmental conditions with algal speciation. Typical of near-shore Antarctic waters, biomass was dominated by large diatoms, although the prymnesiophyte Phaeocystis antarctica was numerically dominant. Although there was considerable interannual variability between main diatom species, high biomass of certain species or species groups corresponded consistently to certain phases of seasonal progression. We present the first documentation of an extensive bloom of the late-season diatom Proboscia inermis in February 2006, accounting for over 90% of diatom biomass. At this time, water column stratification and nutrient drawdown were high relative to other periods of the study, although carbon export was relatively low. Melt water flux in this region promotes well-stratified surface waters and high chlorophyll levels, but not necessarily concurrent increases in export production relative to seasons with lower freshwater inputs.
(Polar Biology. vol. 33, n° 0722-4060, pp. 13-29, 01/01/2010)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BAS, NERC
Deciphering of six blocks of Gondwanan origin within Eastern Indonesia (South East Asia)
The French Indonesian research programs, both conducted on land and offshore in the Banda Sea basins area, have led us to formulate a new interpretation of the East Indonesian geological components. In this area we distinguish, within the three main tectonic plates (Eurasian, Indo-Australian and Philippine-Pacific), seven blocks. Six blocks are deciphered as issued from the north-eastern Gondwanan margin and only one (the Halmahera block) issued from the Pacific plate. Among the Gondwanan blocks, two of them, namely Timor (probably originates from "Greater India") and Kolonodale (or the Argo block) came from the north-west Australian margin. The Lucipara, Seram and Banggai-Sula blocks originated from the western extension of the Papua-New Guinea Island while the Irian Jaya block is still linked to the North Australian margin. The last one, the Halmahera block, originated from the Pacific plate, moved westward along the North Papua-New-Guinea margin up to its present position in the northern part of the Banda Sea area. Our interpretation is mainly based on the lithostratigraphic succession, the geological evolution and the Early Mesozoic paleoposition of these blocks with respect to the climatic environment deduced from micropaleontological studies. According to previous studies, the Timor and Kolonodale blocks were detached from Gondwana during the Jurassic whereas the Lucipara, Seram and Banggai-Sula blocks were detached from Papua-New Guinea Island during the Neogene period. All these Gondwanan blocks collided with the Eurasian active margin, in the vicinity of Sulawesi Island: Timor and Kolonodale had joined the Eurasian margin by the end of the Paleogene, while Lucipara, Seram and Banggai-Sula collided with Sulawesi Island between the Middle Miocene to Middle Pliocene. After the collisions the last three blocks together with the Kolonodale block did not move again but suffered the opening of North and South Banda back-arc basins, by the Late Miocene. On the contrary, part of the Timor block moved south together with the southern margin of the south Banda basin and, later on during the middle Pliocene, collided with the northern Australian margin. The detachment of these blocks from the Gondwana margin, and their amalgamation with the Eurasian margin, are discussed and illustrated through palaeogeographic maps.
(Gondwana Research. vol. 18, n° 1342-937X, pp. 420-437, 24/02/2026)
FRE 2761, CNRS, UNIGE, LDO, INSU - CNRS, UBO EPE, CNRS, PEPS, UCBL, INSU - CNRS, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, Unhas, ISTO, INSU - CNRS, UO, UT, CNRS, iSTeP, UPMC, CNRS, LPGN, UN, CNRS
Abrupt climate changes of the last deglaciation detected in a Western Mediterranean forest record
Abrupt changes in Western Mediterranean climate during the last deglaciation (20 to 6 cal ka BP) are detected in marine core MD95-2043 (Alboran Sea) through the investigation of high-resolution pollen data and pollen-based climate reconstructions by the modern analogue technique (MAT) for annual precipitation (Pann) and mean temperatures of the coldest and warmest months (MTCO and MTWA). Changes in temperate Mediterranean forest development and composition and MAT reconstructions indicate major climatic shifts with parallel temperature and precipitation changes at the onsets of Heinrich stadial 1 (equivalent to the Oldest Dryas), the Bölling-Allerød (BA), and the Younger Dryas (YD). Multi-centennial-scale oscillations in forest development occurred throughout the BA, YD, and early Holocene. Shifts in vegetation composition and (Pann reconstructions indicate that forest declines occurred during dry, and generally cool, episodes centred at 14.0, 13.3, 12.9, 11.8, 10.7, 10.1, 9.2, 8.3 and 7.4 cal ka BP. The forest record also suggests multiple, low-amplitude Preboreal (PB) climate oscillations, and a marked increase in moisture availability for forest development at the end of the PB at 10.6 cal ka BP. Dry atmospheric conditions in the Western Mediterranean occurred in phase with Lateglacial events of high-latitude cooling including GI-1d (Older Dryas), GI-1b (Intra-Allerød Cold Period) and GS-1 (YD), and during Holocene events associated with high-latitude cooling, meltwater pulses and N. Atlantic ice-rafting. A possible climatic mechanism for the recurrence of dry intervals and an opposed regional precipitation pattern with respect to Western-central Europe relates to the dynamics of the westerlies and the prevalence of atmospheric blocking highs. Comparison of radiocarbon and ice-core ages for well-defined climatic transitions in the forest record suggests possible enhancement of marine reservoir ages in the Alboran Sea by 200 years (surface water age 600 years) during the Lateglacial.
(Climate of the Past. vol. 6, n° 1814-9324, pp. 245-264, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL, LCE, CNRS, UFC, UBFC
How life history contributes to stress response in the Manila clam Ruditapes philippinarum
Introduction Within the last decade, numerous studies have investigated the role of environmental history on tolerance to stress of many organisms. This study aims to assess if Manila clams Ruditapes philippinarum may react differently to cadmium exposure and trematode parasite infection (Himasthla elongata) depending on their origin and environmental history in Arcachon Bay (France). Materials and methods Clams were exposed to Cd (15 µg L−1) and parasites (25 cercariae per clam), alone or in combination, at 15°C under controlled laboratory conditions for 7 days. Metal accumulation and success of parasite infestation were examined, also physiological parameters such as metallothionein response and hemocyte counts and activities (phagocytosis, oxidative burst, viability, and adhesion). Results and Discussion Sensitivity of Manila clams to both stressors differed from one site to another, suggesting local adaptation of populations. Clams from the more parasitized site presented better resistance to trematodes than the others in terms of first line defense, i.e., avoidance of infection. On the other hand, clams that adapted to chronic Cd contamination showed better detoxification mechanisms, both in a faster transfer of metal from gills to visceral mass and in a higher metallothionein baseline, than clams which had never experienced Cd contamination. Finally, hemocyte concentration and viability differed between clam origin site, highlighting the fact that populations living in different environments may adapt their physiological and biochemical responses to environmental stressors. Conclusion It is therefore important to be cautious when extrapolating results from field studies of one species and one site, if the life history of the organisms is not taken into account.
(Environmental Science and Pollution Research. vol. 17, n° 0944-1344, pp. 987-998, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
A robust statistical framework for QTL analysis
(24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS, MSH
Evènements extrêmes en Afrique de l'ouest durant le dernier glaciaire et l'Holocène
(24/02/2026)
OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, L3AB, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, LAB, UB, INSU - CNRS, CNRS, UB, LGF, UP1, CNRS
Exploitation of trophic resources by fish under stressful estuarine conditions
Despite the high complexity and variability of estuaries, these ecosystems are very productive and play an important role in fish feeding. This paper constitutes a preliminary investigation to test how fish optimize the use of the available trophic resources, by studying trophic preference variability and feeding strategies of some pelagic and demersal fish in the Gironde estuary (southwest France). Fish and their prey were collected approximately every two months from July 2003 to June 2004 in the upstream area of the saline estuary. Stomach content analyses were realized to describe the variability of fish feeding according to their size and the time of year. Intra- and interspecific food niche overlap was evaluated using Schoener's index and a cross-calculation method was used to highlight the general fish trends in predation strategy. Stomach content results showed interspecific and intraspecific variability in fish feeding, which can be explained by their different or evolutionary ecomorphology. Their diets are composed mainly of zooplankton and hyperbenthic crustaceans with temporal variations in the consumed taxa. Optimization of the available trophic resource use, a key element in estuarine resilience, is thus possible due to the temporal adaptation of this structural trophic web. However, in spite of their temporal adaptation capacity, most fish species exhibited a specialist feeding strategy. This result was not expected, especially in the high turbidity of the Gironde estuary; the loss of one of these species could affect the fish trophic web structure and hence the resilience of the system.
(Marine Ecology Progress Series. vol. 400, n° 0171-8630, pp. p. 207 - p. 219, 24/02/2026)
UR EPBX, CEMAGREF, LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Highstand vs. lowstand turbidite system growth in the Makran active margin: Imprints of high-frequency external controls on sediment delivery mechanisms to deep water systems
Late Quaternary turbidite system growth along the Makran convergent margin is investigated through a set of deep-sea cores from upper slope and piggy-back basins to deep basin plain settings. High-resolution stratigraphy in these various depositional environments permits reconstruction of the evolution of sand-to-mud ratio, sedimentation rates, frequencies, and thickness of turbidite deposits during the last 25 ka BP. This study demonstrates how tectonics, climate and eustasy can interplay at high resolution (< 20 ka) and control the input of terrigeneous sediment along the tectonically active Makran convergent margin, in a source-to-sink perspective. The Makran turbidite system growth has been continuous throughout sea-level lowstand, transgressive, and highstand conditions. However, the frequency, rates, and nature of sediment supply varied in response to climate, sea-level, and tectonically induced changes in source-to-sink sediment dispersal modes. These changes include conditions of sediment production and availability in the drainage basin, capacity of transport from fluvial systems, and rates of sediment storage on the shelf and upperslope areas. Climate in the hinterland appears as a first-order control on the properties of turbidity currents that feed the turbidite system, controlling the average sand-to-mud ratio in the deep water deposits. The onset of sea-level highstand after ∼ 8 ka BP resulted in a notable change in turbidite system growth, characterized by the occurrence of large volume, thick turbidity currents (> 300 m thick along the continental slope) originated from successive, multiple slide or slump-induced surges. Their related deposits have low recurrence intervals, close to those calculated from the large magnitude earthquake and tsunami record in the Makran area. Comparison with the Nile and Indus turbidite systems growth during the Late Quaternary provides an evaluation of the relative importance of shared forcing parameters (i.e. monsoon-induced phases of arid/humid conditions and post-glacial sea-level rise), in significantly different basin settings. The Indus fan appears mainly controlled by eustasy during the last 25 ka. Inversely, similarities are found between the Nile and Makran turbidite systems, where sea-level changes are modulated by the climate impact on fluvial dynamics in the hinterland. However, the Makran turbidite system growth is continuous through times, because both the uplift in the coastal area and the fluvial dynamics of short, mountainous river systems allow high sediment transfer rates to the marine basin, even though arid conditions and associated low water fluxes. Earthquake-induced highstand turbidite deposits form a thick sedimentary succession in the Oman abyssal plain, and are significant in the geologic record. This study finally illustrates how the complex interplay between external (allogenic) forcings can complicate the interpretation of high-resolution sedimentary successions in turbidite-filled basins.
(Marine Geology. vol. 274, n° 0025-3227, pp. 187 - 208, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFP, VU, SHOM, IFREMER
Spatio-temporal patterns of perkinsosis in the Manila clam Ruditapes philippinarum from Arcachon Bay (SW France)
Pathogens belonging to the genus Perkinsus infect many bivalve molluscan species around the world, including the Manila clam Ruditapes phihppinarum. We investigated the spatial distribution of this parasite at 34 stations throughout Arcachon Bay (SW France). Prevalence of perkinsosis was 93% and mean infection abundance was 96 x 10(3) cells g(-1) wet gill. Lowest mean abundances were found close to the Leyre River mouth and a significant negative correlation was observed between mean abundance and salinity. Perkinsosis was rare at the oceanic site where salinities and other environmental parameters were stable. A second aim of this study was to survey perkinsosis during annual cycles at 4 sites within Arcachon Bay. Prevalence and intensities (+/-SE) of the disease were high, on average between 70 and 100%, and 130 x 10(3) +/- 6.7 x 10(3) cells g(-1) wet gill. No seasonal cycle was evident. Clams were infected at 9 mm shell length and infection increased with clam size. The third objective was to determine the disinfection and infection kinetics through a 21 mo reciprocal transplantation between a nearly Perkinsus sp.-free area and a highly affected site. Disinfection appeared to be a very slow process and was similar at the site with favorable conditions for Perkinsus sp. as at the site with unfavorable conditions. Conversely, infection acquisition appeared to be episodic with spatially defined areas. Consequently, the overall lack of a clear seasonal infection pattern is interpreted as the combination of episodic infection events and slow disinfection kinetics.
(Diseases of Aquatic Organisms. vol. 91, n° 0177-5103, pp. 151-159, 24/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LRHA, HGS, IFREMER