Disentangling the heritable and plastic components of the competitive and facilitative effects of an alpine foundation species
1- Differences in effects between phenotypes of foundation species on subordinate species have been reported, but no study has separated their heritable and plastic components. In a subalpine community of the French Pyrenees, we observed two phenotypes of Festuca gautieri: tight cushions in dry convex outcrops with few subordinate species and loose cushions in wet concave slopes with many subordinate species, suggesting differences in effects of the two phenotypes on subordinates. 2- Using two reciprocal transplantation gardens, we studied the responses of the two phenotypes to changes in environmental conditions, thus assessing the contribution of heritability and plasticity to the phenotypic variation. Using a target cross-transplantation experiment, we assessed the plasticity and heritability bases of their contrasting effects. We also quantified the recolonization of resident plants within the reciprocally transplanted cushions. 3- We found that morphological differences between cushions had both heritability and plasticity bases. The two competition experiments showed heritable increase in competitive effects from loose to tight cushions. This was counteracted by plasticity effects, which decreased competition from the benign to the stressful garden. 4- Synthesis. We conclude that heritable effects overcome plasticity effects resulting in higher diversity in the loose phenotype from the benign habitats.
(Journal of Ecology. vol. 103, n° 0022-0477, pp. 1172–1182, 23/04/2026)
BioGeCo, INRA, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Corticosterone, prolactin and egg neglect behavior in relation to mercury and legacy POPs in a long-lived Antarctic bird
Seabirds often have high loads of contaminants. These contaminants have endocrine disrupting properties but their relationships with some endocrine mechanisms are still poorly investigated in free-living organisms. This is the case for the stress response which shifts energy investment away from reproduction and redirects it towards survival. In birds, this stress response is achieved through a release of corticosterone and is also accompanied by a decrease in circulating prolactin, an anterior pituitary hormone widely involved in regulating parental cares. We measured blood concentrations of some legacy persistent organic pollutants (POPs) and mercury (Hg) and examined their relationships with the corticosterone and prolactin responses of known-age (9-46 years old) incubating snow petrels (Pagodroma nivea) to a standardized capture/handling stress protocol. In this Antarctic seabird, we also investigated whether high contaminant burden correlates with a higher occurrence of egg neglect, a frequently observed behaviour in snow petrels. POPs and Hg were unrelated to age. Stress-induced corticosterone concentrations were positively related to POPs in both sexes, and stress-induced prolactin concentrations were negatively related to Hg in males. Egg-neglect behaviour was not related to POPs burden, but males with higher Hg concentrations were more likely to neglect their egg. This suggests that in birds, relationships between age and contaminants are complex and that even low to moderate concentrations of POPs and Hg are significantly related to hormonal secretion. In this Antarctic species, exposure to legacy POPs and Hg could make individuals more susceptible to environmental stressors such as ongoing disturbances in polar regions.
(Science of the Total Environment. vol. 505, n° 0048-9697, pp. 180 - 188, 23/04/2026)
CEBC, INRA, ULR, CNRS, UC, LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NINA, NINA
Dynamics of inner-shelf, multi-scale bedforms off the south Aquitaine coast over three decades (Southeast Bay of Biscay, France)
This paper aims to investigate the seabed morphodynamics of the south Aquitaine inner shelf in the area known as “La Salie” (150 km2, Atlantic ocean, west coast of France), through a descriptive and comparative analysis (time lapse of 29 years) of geophysical and sedimentological datasets.At a water depth of 24–50 m, four orders of sedimentary body types were observed at different scales. The first order are large cross-shore “morphological ridges,” corresponding with the properties of very large sorted bedforms. The second order consisted in patchy sorted bedforms, composed of alternately medium to fine sand patches (0.5–2 m in thickness), cut by smaller, elongated coarse sediment depressions. In particular, the data from the sub-bottom profiler revealed that sand patches predominantly overlayed the coarse-grained blankets on the eastern (shoreward) extremities, while coarse-grained blanket wedges were found in front of the sand patches (southwestward) or locally overlying them on the southwestern extremities. The third order of bedforms involved groups of dune-like features (fine/medium sand), lying in wide areas of coarse-grained sediment. Finally, in the fouth order, the entire inner shelf was covered with wave-generated ripples, oriented N15°, that were larger where sediments were coarse (wavelengths of 2.2 m) than where sediments were fine (wavelengths of 0.3 m). Over the past 29 years, at a large scale of observation, patchy sorted bedforms have remained remarkably persistent, as has their overall appearance. However, at a smaller scale, weak but constant movements were observed. The coarse depressions have become elongated at their extremities (by a maximum of 300 m over 15 years), and certain coarse/fine sediment boundaries have moved toward the northeast and southeast (by a maximum of 75 m over 12 years). The general movement has been shoreward as has the migration of third-order submarine dune-like features. The persistence of sorted bedforms thus appears to be the consequence of sediment sorting feedback and recurrent storm events.
(Continental Shelf Research, n° 0278-4343, pp. pp. 23-36, 23/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, SHOM
Methylmercury effects on migratory behaviour in glass eels (Anguilla anguilla) : an experimental study using isotopic tracers
The effect of methylmercury (MeHg) on glass eels' propensity to migrate, mitochondrial activity and antioxidative defence systems was investigated. Marine glass eels were first sorted in an experimental flume according to their response to dusk. Fish responding to the decrease in light intensity by ascending in the water column and moving with or against the flow were considered as having a high propensity to migrate (migrant). Glass eels still sheltering at the end of the 24 h catching period were considered as having a low propensity to migrate and were called non-migrant. Migrant and non-migrant glass eels were then individually tagged and exposed to isotopically enriched 201MeHg (50 ng L− 1) for 11 days. The effect of contamination was studied on muscle fibre structure, and the expression level of genes involved in mitochondrial activity and antioxidative defence systems. To investigate the effect of MeHg on glass eel behaviour, migrant and non-migrant glass eels were sorted again and the bioaccumulation of 201MeHg and its demethylation product (201Hg(II)) were determined for each individual. MeHg exposure increased activity in non-migrant glass eels but not migratory behaviour. Contamination affected mitochondrial structure and metabolism and suggests a higher oxidative stress and activation of antioxidative defence systems in non-migrant glass eels. Overall, our results suggest that exposure to MeHg might induce an increase in energy expenditure and a higher vulnerability to predation in non-migrant glass eels in the wild
(Comparative Biochemistry and Physiology - Part C: Toxicology and Pharmacology. vol. 171, n° 1532-0456, pp. 15-27, 23/04/2026)
ECOBIOP, INRA, UPPA, IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Toward Sentinel-2 High Resolution Remote Sensing of Suspended Particulate Matter in Very Turbid Waters: SPOT4 (Take5) Experiment in the Loire and Gironde Estuaries
At the end of the SPOT4 mission, a four-month experiment was conducted in 2013 to acquire high spatial (20 m) and high temporal (5 days) resolution satellite data. In addition to the SPOT4 (Take5) dataset, we used several Landsat5, 7, 8 images to document the variations in suspended particulate matter (SPM) concentration in the turbid Gironde and Loire estuaries (France). Satellite-derived SPM concentration was validated using automated in situ turbidity measurements from two monitoring networks. The combination of a multi-temporal atmospheric correction method with a near-infrared to visible reflectance band ratio made it possible to quantify SPM surface concentration in moderately to extremely turbid waters (38-4320 g·m-3), at an accuracy sufficient to detect the maximum turbidity zone (MTZ) in both estuaries. Such a multi-sensor approach can be applied to high spatial resolution satellite archives and to the new ESA Sentinel-2 mission. It offers a promising framework to study the response of estuarine ecosystems to global changes at unprecedented spatio-temporal resolution.
(Remote Sensing. vol. 7, n° 2072-4292, pp. 9507-9528, 23/04/2026)
MMS, UM, UN UFR ST, UN, UFR SPB, UN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comparison of kernel density estimators with assumption on number of modes
A data-driven bandwidth choice for a kernel density estimator called critical bandwidth is investigated. This procedure allows the estimation to have as many modes as assumed for the density to estimate. Both Gaussian and uniform kernels are considered. For the Gaussian kernel, asymptotic results are given. For the uniform kernel, an argument against these properties is mentioned. These theoretical results are illustrated with a simulation study which compare the kernel estimators that rely on critical bandwidth with another one which uses a plug-in method to select its bandwidth. An estimator that consists in estimates of density contour clusters and takes assumptions on number of modes into account is also considered. Finally, the methodology is illustrated using environment monitoring data.
(Communications in Statistics - Simulation and Computation. vol. 44, n° 0361-0918, pp. 196-216, 23/04/2026)
IMB, UB, Bordeaux INP, CNRS, CQFD, IMB, UB, Bordeaux INP, CNRS, Inria, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Extreme sea events during the last millennium in the northeast of Morocco
The Moroccan Mediterranean coast is located in one of the area's most vulnerable to extreme weather events or tsunami hazards. The objective of this research is to reconstruct the historical extreme submersion-event record using sea-induced deposits preserved in coastal lagoon. The Nador lagoon is the largest Moroccan lagoon (115 km2). It is located along the western Mediterranean, which has a high cyclogenetic character and is exposed to tsunamis from the Alboran Sea. The sandy barrier which separates the lagoon from the Mediterranean Sea is marked by much overwash, which indicate how intensely it has been exposed to the adverse sea events through history. Using the UWITEC© gravity coring platform, an undisturbed MC4.5 core (1.15 m long) was successfully sampled in the studied lagoon. To identify extreme sea events, a multi-proxy approach was applied combining sedimentological and geochemical data. Three paleoevents were identified; all of them are concentrated over the last 500 years, and the most recent event corresponds to the 1889 storm. For the others deposits, it is difficult to determine exactly their origin; however, the high frequency of storm events over the relevant period and the absence of historical tsunamis evidence is more in favor of the meteorological origin.
(Natural Hazards and Earth System Sciences. vol. 15, n° 1561-8633, pp. 203-211, 23/04/2026)
INSU - CNRS, UM, CNRS, UA, Géosciences Montpellier, UAG, INSU - CNRS, UM, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEOTRAC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Specific Pathways of Dietary Methylmercury and Inorganic Mercury Determined by Mercury Speciation and Isotopic Composition in Zebrafish (Danio rerio)
An original approach is proposed to investigate inorganic (iHg) and methylmercury (MeHg) trophic transfer and fate in a model fish, Danio rerio, by combining natural isotopic fractionation and speciation. Animals were exposed to three different dietary conditions: (1) 50 ng Hg g-1, 80% as MeHg; (2) diet enriched in MeHg 10000 ng Hg g-1, 95% as MeHg, and (3) diet enriched in iHg 10000 ng Hg g-1, 99% as iHg. Harvesting was carried out after 0, 7, 25, and 62 days. Time-dependent Hg species distribution and isotopic fractionation in fish organs (muscle, brain, liver) and feces, exhibited different patterns, as a consequence of their dissimilar metabolization. The rapid isotopic re-equilibration to the new MeHg-food source reflects its high bioaccumulation rate. Relevant aspects related to Hg excretion are also described. This study confirms Hg isotopic fractionation as a powerful tool to investigate biological processes, although its deconvolution and fully understanding is still a challenge. © 2015 American Chemical Society.
(Environmental Science and Technology. vol. 49, n° 0013-936X, pp. 12984--12993, 23/04/2026)
IPREM, UPPA, INC-CNRS, CNRS, IPREM, UPPA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCABIE, UPPA, CNRS
Specific Effects of Dietary Methylmercury and Inorganic Mercury in Zebrafish (Danio rerio) Determined by Genetic, Histological, and Metallothionein Responses
A multidisciplinary approach is proposed here to compare toxicity mechanisms of methylmercury (MeHg) and inorganic mercury (iHg) in muscle, liver, and brain from zebrafish (Danio rerio). Animals were dietary exposed to (1) 50 ng Hg g-1, 80% as MeHg; (2) diet enriched in MeHg 10000 ng Hg g-1, 95% as MeHg; (3) diet enriched in iHg 10000 ng Hg g-1, 99% as iHg, for two months. Hg species specific bioaccumulation pathways were highlighted, with a preferential bioaccumulation of MeHg in brain and iHg in liver. In the same way, differences in genetic pattern were observed for both Hg species, (an early genetic response (7 days) for both species in the three organs and a late genetic response (62 days) for iHg) and revealed a dissimilar metabolization of both Hg species. Among the 18 studied genes involved in key metabolic pathways of the cell, major genetic responses were observed in muscle. Electron microscopy revealed damage mainly because of MeHg in muscle and also in liver tissue. In brain, high MeHg and iHg concentrations induced metallothionein production. Finally, the importance of the fish origin in ecotoxicological studies, here the seventh descent of a zebrafish line, is discussed. © 2015 American Chemical Society.
(Environmental Science and Technology. vol. 49, n° 0013-936X, pp. 14560--14569, 23/04/2026)
IPREM, UPPA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, LCABIE, UPPA, CNRS
On a new hydrid method to modelize the turbulence over marine sand ripples
(23/04/2026)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER