Dietary bioaccumulation of persistent organic pollutants in the common sole Solea solea in the context of global change. Part 1: Revisiting parameterisation and calibration of a DEB model to consider inter-individual variability in experimental and natural conditions
Studying adverse effects of chemical pressure on aquatic ecosystems needs a comprehensive knowledge of bioaccumulation mechanisms of pollutants in biota to predict internal concentrations, especially for Persistent Organic Pollutants (POPs). However, the large variability of responses in measured POP concentrations requires explicit consideration of both individual variability and environmental influences. Dynamic Energy Budget (DEB) theory provides a rigorous and generic conceptual framework for tackling these questions in a relevant mechanistic way. In the present study, parameterisation and calibration of previous DEB models for Solea solea were revisited in order to accurately represent the full life cycle with an original emphasis on larval stage, metamorphosis, reproduction rules and sexual differences. We first improved calibration thanks to the use of the estimation procedure developed by the DEB network coupled with a broad compilation of data from literature. Then, we validated this set of parameter estimates on independent datasets of i) individual monitoring of larval growth in controlled food conditions from a novel experiment, and ii) juvenile and adult growth, and female fecundity, from a natural population. Finally, we combined the DEB model developed in the present paper with we used a simple toxicokinetic (TK) model from literature. This TK model was also combined to a previous DEB model and was used to reproduce the mean trajectories of a growth and contamination dataset. We applied the same TK model with our DEB model considering inter-individual variability in food availability. This application highlighted the need to accurately consider inter-individual variability in ingestion to correctly estimate growth and contamination variability. The present work is the first step in the development of a mechanistic TK model that will be used in a companion paper for investigations of juvenile sole sensitivity to warming, nursery quality and prey contamination, in highly fluctuating estuarine environments.
(Ecological Modelling. vol. 433, n° 0304-3800, pp. 109224, 01/10/2020)
UR EABX, INRAE, LEMAR, IRD, IFREMER, UBO EPE, CNRS, IRD, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BE, IFREMER, IFREMER
Climate and land-use as the main drivers of recent environmental change in a mid-altitude mountain lake, Romanian Carpathians
Recent decades have been marked by unprecendented environmental changes which threaten the integrity of freshwater systems and their ecological value. Although most of these changes can be attributed to human activities, disentagling natural and anthropogenic drivers remains a challenge. In this study, surface sediments from Lake Ighiel, a mid-altitude site in the Carpathian Mts (Romania) were investigated following high-resolution sedimentological, geochemical, environmental magnetic and diatom analyses supported by historical cartographic and documentary evidence. Our results suggest that between 1920 and 1960 the study area experienced no significant anthropogenic impact. An excellent correspondence is observed between lake proxy responses (e.g., growth of submerged macrophytes, high detrital input, shifts in diatom assemblages) and parameters tracking natural hydroclimate variability (e.g., temperature, NAO). This highlights a dominant natural hydroclimatic control on the lacustrine system. From 1960 however, the depositional regime shifted markedly from laminated to homogenous clays; since then geochemical and magnetic data document a trend of significant (and on-going) subsurface erosion across the catchment. This is paralleled by a shift in lake ecosystem conditions denoting a strong response to an intensified anthropogenic impact, mainly through forestry. An increase in detrital input and marked changes in the diatom community are observed over the last three decades, alongside accelerated sedimentation rates following enhanced grazing and deforestation in the catchment. Recent shifts in diatom assemblages may also reflect forcing from atmospheric nitrogen (N) deposition, a key recent drive of diatom community turnover in mountain lakes. In general, enhanced human pressure alongside intermittent hydroclimate forcing drastically altered the landscape around Lake Ighiel and thus, the sedimentation regime and the ecosystem’s health. However, paleoenvironmental signals tracking natural hydroclimate variability are also clearly discernible in the proxy data. Our work illustrates the complex link between the drivers of catchment-scale impacts on one hand, and lake proxy responses on the other, highlighting the importance of an integrated historical and palaeolimnological approach to better assess lake system changes.
(PLoS ONE. vol. 15, n° 1932-6203, pp. e0239209, 01/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UK, ICUB, UniBuc, UK
Quaternary sediment dispersal in the Zambezi turbidite system (SW Indian Ocean)
Some of the authors of this publication are also working on these related projects: Modeling sediment supply of the Congo watershed since the last 155 ka View project Submarine landslides in the Northern Tyrrhenian Sea and relationship with the contouritic and turbiditic deposits: morphology, stratigraphy, geotechnics and modelling View project Ruth Fierens Université de Bretagne Occidentale
(Marine Geology. vol. 428, n° 0025-3227, pp. 106276, 01/10/2020)
LGO, UBS, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Growth and behaviour of blue mussels, a re-emerging polar resident, follow a strong annual rhythm shaped by the extreme high Arctic light regime
Polar regions are currently warming at a rate above the global average. One issue of concern is the consequences on biodiversity in relation to the Northward latitudinal shift in distribution of temperate species. In the present study, lasting almost two years, we examined two phenological traits, i.e. the shell growth and behavioural rhythm of a recently re-established species in the high Arctic, the blue mussel Mytilus sp. We compared this with a native species, the Islandic scallop Chlamys islandica. We show marked differences in the examined traits between the two species. In Mytilus sp., a clear annual pattern of shell growth strongly correlated to the valve behaviour rhythmicity, whereas C. islandica exhibited a shell growth pattern with a total absence of annual rhythmicity of behaviour. The shell growth was highly correlated to the photoperiod for the mussels but weaker for the scallops. The water temperature cycle was a very weak parameter to anticipate the phenology traits of both species. This study shows that the new resident in
(Royal Society Open Science. vol. 7, n° 2054-5703, pp. 200889, 01/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comparison of imidacloprid, propiconazole, and nanopropiconazole effects on the development, behavior, and gene expression biomarkers of the Pacific oyster (Magallana gigas)
(Science of the Total Environment, n° 0048-9697, pp. 142921, 01/10/2020)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS
High‐Energy Surf Zone Currents and Headland Rips at a Geologically Constrained Mesotidal Beach
We analyze Eulerian and Lagrangian measurements of wave-induced circulation collected during a 3-week field experiment at a high-energy mesotidal barred beach with the presence of a 500-m headland and a submerged reef. Small changes in wave and tide conditions were found to largely impact circulation patterns. Three main regimes were identified depending on offshore wave obliquity: (1) Under shore-normal configuration, the flow was dominated by cross-shore motions, except for moderate waves at low tide, with the presence of a quasi-steady circulation cell on the reef. (2) Under shadowed configuration, an onshore-directed current flowing away from the headland and a weak oscillating eddy were present outside and inside the shadow region, respectively. (3) Under deflection configuration, a deflection rip flowing against the headland and extending well beyond the surf zone was present, with activity maximized around low tide for moderate waves. Under 4-m oblique waves, the deflection rip was active regardless of the tide with mean depth-averaged velocities up to 0.7 m/s 800-m offshore in 12-m depth, with energetic low-frequency fluctuations. Our results emphasize the ability of deflection rips to transport materials far offshore, suggesting that such rips can transport sediment beyond the depth of closure. This study indicates that a wide variety of wave-driven circulation patterns can occur and sometimes coexist on beaches with prominent geological settings. Changes in the dominant driving mechanism can occur as a result of small changes in wave and tide conditions, resulting in more spatially and temporally variable circulation than along open sandy beaches. Plain Language Summary Most field experiments about wave-induced circulation patterns have been conducted along open sandy beaches, while experiments in geologically constrained environments are scarce. We performed intensive field measurements at a high-energy beach with the presence of a 500-m headland and a submerged natural reef. Three main circulation patterns were identified depending on the offshore wave obliquity. For shore-normal waves, cross-shore motions dominated the nearshore region, while oblique wave configurations resulted in more complex horizontal circulation. In particular, under intense headland-directed longshore current, the flow was deflected seaward against the headland. This deflection resulted in an intense seaward flowing jet (deflection rip) extending well beyond the surf zone edge, particularly during storm conditions. Such findings highlight the ability of these deflection rips to dominate water and sediment exchanges between the nearshore and the inner shelf region. Our study further outlines the more spatially and temporally variable circulation patterns occurring along geologically constrained beaches compared to open sandy beaches, ranging from small recirculating cells across the reef to a large deflection rip extending hundreds of meters beyond the surf zone.
(Journal of Geophysical Research. Oceans. vol. 125, n° 2169-9275, 01/10/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SIAME, UPPA
Mobilisation of data to stakeholder communities. Bridging the research-practice gap using a commercial shellfish species model
Knowledge mobilisation is required to “bridge the gap” between research, policy and practice. This activity is dependent on the amount, richness and quality of the data published. To understand the impact of a changing climate on commercial species, stakeholder communities require better knowledge of their past and current situations. The common cockle (Cerastoderma edule) is an excellent model species for this type of analysis, as it is well-studied due to its cultural, commercial and ecological significance in west Europe. Recently, C. edule harvests have decreased, coinciding with frequent mass mortalities, due to factors such as a changing climate and diseases. In this study, macro and micro level marine historical ecology techniques were used to create datasets on topics including: cockle abundance, spawning duration and harvest levels, as well as the ecological factors impacting those cockle populations. These data were correlated with changing climate and the Atlantic Multidecadal Oscillation (AMO) index to assess if they are drivers of cockle abundance and harvesting. The analyses identified the key stakeholder communities involved in cockle research and data acquisition. It highlighted that data collection was sporadic and lacking in cross-national/stakeholder community coordination. A major finding was that local variability in cockle populations is influenced by biotic (parasites) and abiotic (temperature, legislation and harvesting) factors, and at a global scale by climate (AMO Index). This comprehensive study provided an insight into the European cockle fishery but also highlights the need to identify the type of data required, the importance of standardised monitoring, and dissemination efforts, taking into account the knowledge, source, and audience. These factors are key elements that will be highly beneficial not only to the cockle stakeholder communities but to other commercial species.
(PLoS ONE. vol. 15, n° 1932-6203, pp. e0238446, 23/09/2020)
UCC, ULISBOA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NERC, GEMEL-Normandie
Direct and indirect facilitation affect community productivity through changes in functional diversity in an alpine system
Abstract Background and Aims Facilitation is an important ecological process for plant community structure and functional composition. Although direct facilitation has accrued most of the evidence so far, indirect facilitation is ubiquitous in nature and it has an enormous potential to explain community structuring. In this study, we assess the effect of direct and indirect facilitation on community productivity via taxonomic and functional diversity. Methods In an alpine community on the Tibetan Plateau, we manipulated the presence of the shrub Dasiphora fruticosa and graminoids in a fenced meadow and a grazed meadow to quantify the effects of direct and indirect facilitation. We measured four plant traits: height, lateral spread, specific leaf area (SLA) and leaf dry matter content (LDMC) of forbs; calculated two metrics of functional diversity [range of trait and community-weighted mean (CWM) of trait]; and assessed the responses of functional diversity to shrub facilitation. We used structural equation modelling to explore how shrubs directly and indirectly drove community productivity via taxonomic diversity and functional diversity. Key Results We found stronger effects from herbivore-mediated indirect facilitation than direct facilitation on productivity and taxonomic diversity, regardless of the presence of graminoids. For functional diversity, the range and CWM of height and SLA, rather than lateral spread and LDMC, generally increased due to direct and indirect facilitation. Moreover, we found that the range of traits played a primary role over taxonomic diversity and CWM of traits in terms of shrub effects on community productivity. Conclusions Our study reveals that the mechanism of shrub direct and indirect facilitation of community productivity in this alpine community is expanding the realized niche (i.e. expanding range of traits). Our findings indicate that facilitators might increase trait dispersion in the local community, which could alleviate the effect of environmental filters on trait values in harsh environments, thereby contributing to ecosystem functioning.
(Annals of Botany. vol. 127, n° 0305-7364, pp. 241-249, 17/09/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A new species of Marphysa (Annelida: Eunicida: Eunicidae) from India, with notes on previously described or reported species from the region
A new species of Marphysa is described from India using both morphology and molecular data. The new species, Marphysa madrasi, belonging to the Teretiuscula-group, is characterised by having antennae about 2x longer than the prostomium, maxillae II and IV with a relatively large number of teeth (Mx II with 8+9; Mx IV with 7+11), compound spinigers present on a large range of mid-body chaetigers (at least 83–159), and pectinate chaetae present from the first few anterior chaetigers. We discuss all the species of this genus lacking compound falcigers (i.e., those belonging to the Sanguinea-, Mossambica- and Teretiuscula-groups), which have been reported from India and compare them to our new species. Only two accepted species in these groups can be confirmed as occurring in India, M. madrasi n. sp. and M. gravelyi Southern, 1921. We provide a table that summarises the important characters useful to identify species in this group of Marphysa with compound spinigers.
(Zootaxa, n° 1175-5326, 16/09/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Reconstruction of the Tiber Deltaic stratigraphic successions near Ostia using the PADM chart and tracking of the bedload-derived facies (Rome, Italy)
Located between the deltaic plain and the subaqueous delta, base level is one of the most important factors that affect depositional elements and the sedimentary architecture of river deltas. In this respect, its changes are essential to reconstruct delta evolution during the Holocene. In this paper, we study three cores drilled in the Tiber delta (Italy). Palaeoenvironmental analyses were performed and included new sedimentological data (laser grain size, loss-on-ignition, magnetic susceptibility), new data from bioindicators (ostracods and macrofauna), and 11 new radiocarbon dates. The three cores were analysed and replaced in a cross section between the Inner and Outer Tiber delta, i.e.,in the palaeolagoon and in the progradational delta plain. First, we have mapped the Holocene transgression and progradation of the Ostia area using palaeoenvironmental age-depth modelling techniques (PADMs). PADM charts help to interpret a stratigraphic succession in a river delta. They contribute to the understanding of the links between depositional environments, sedimentation rate, and sea level rise and to reconstruct coastline trajectories. More precisely, they contribute to the interpretation of the consequences of the sea level jumps dated to the 9000–8000 cal. BP period on coastal environments and help to identify progradational phases (around 4 k, and from 2.8 to 2.6 k cal. BP). Second, we identify indirect (freshwater bioindicators) and direct (bedload-derived facies) evidence of fluvial activity in the studied cross section. The studied deep cores indicate that at least one palaeochannel of the Tiber River was already flowing in the middle/southern part of the delta from 4 k cal. BP. Finally, a first map of the lateral mobility of the palaeochannels of the Tiber River is proposed for the last 6 k cal. BP using the new data and a synthesis of all the data available at the scale of the delta.
(Geomorphology. vol. 365, n° 0169-555X, pp. 107227, 15/09/2020)
LIVE, UNISTRA, CNRS, Archéorient, UL2, CNRS, EVS, ENS de Lyon, Mines Saint-Étienne MSE, IMT, UL2, UJML, INSA Lyon, INSA, UJM, ENTPE, ENSAL, CNRS, ALLHiS, UJM, AGEs, ULiège, Is.I.P.U., CNR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EVEHA, UNIROMA