Biomarker responses and accumulation of polycyclic aromatic hydrocarbons in Mytilus trossulus and Gammarus oceanicus during exposure to crude oil
In the brackish water Baltic Sea, oil pollution is an ever-present and significant environmental threat mainly due to the continuously increasing volume of oil transport in the area. In this study, effects of exposure to crude oil on two common Baltic Sea species, the mussel Mytilus trossulus and the amphipod Gammarus oceanicus, were investigated. The species were exposed for various time periods (M. trossulus 4, 7, and 14 days, G. oceanicus 4 and 11 days) to three oil concentrations (0.003, 0.04, and 0.30 mg L-1 based on water measurements, nominally aimed at 0.015, 0.120, and 0.750 mg L-1) obtained by mechanical dispersion (oil droplets). Biological effects of oil exposure were examined using a battery of biomarkers consisting of enzymes of the antioxidant defense system (ADS), lipid peroxidation, phase II detoxification (glutathione S-transferase), neurotoxicity (acetylcholinesterase inhibition), and geno- and cytotoxicity (micronuclei and other nuclear deformities). In mussels, the results on biomarker responses were examined in connection with data on the tissue accumulation of polycyclic aromatic hydrocarbons (PAH). In M. trossulus, during the first 4 days of exposure the accumulation of all PAHs in the two highest exposure concentrations was high and was thereafter reduced significantly. Significant increase in ADS responses was observed in M. trossulus at 4 and 7 days of exposure. At day 14, significantly elevated levels of geno- and cytotoxicity were detected in mussels. In G. oceanicus, the ADS responses followed a similar pattern to those recorded in M. trossulus at day 4; however, in G. oceanicus, the elevated ADS response was still maintained at day 11. Conclusively, the results obtained show marked biomarker responses in both study species under conceivable, environmentally realistic oil-in-seawater concentrations during an oil spill, and in mussels, they are related to the observed tissue accumulation of oil-derived compounds.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 15498-15514, 01/05/2020)
NORCE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Holocene fire and vegetation dynamics in the Central Pyrenees (Spain)
Fire-vegetation relationships are critical to understand transient mountain ecosystems and their long-term landscape dynamics, which is essential for alpine forest conservation. In this paper we aim to (1) reconstruct the Holocene fire history at high altitudes of the southern Central Pyrenees, (2) add evidence to the debate on fire origin, naturally or anthropogenically produced, (3) determine the importance of fire as a disturbance agent for sub-alpine and alpine vegetation, in comparison with the plant community internal dynamics applying conditional inference trees. We present and compare microcharcoal and pollen data series, from two lacustrine se-dimentary sequences in the Central Pyrenees: Basa de la Mora (BSM), within the treeline ecotone at the sub-alpine belt (1914 m a.s.l.) and Marboré Lake, above the treeline at the alpine belt (2612 m a.s.l.). We evidence that, fire activity was not the most important factor in driving vegetation dynamics regionally. Our results suggest that spatially, the fire signal might be site-dependent while over time, climate exerted a strong influence on fire activity during the early-to-mid Holocene, showing more fires during the Holocene Thermal Maximum (HTM) (ca. 7000-6000 cal yr BP) whereas fire activity decreased with the cold Neoglacial period. At ca. 3700 cal yr BP, fire activity increased coinciding with a regional landscape opening, suggesting that human activities may have strengthened the importance of fire. Fire activity remained low over the last two millennia but a remarkable Holocene maximum for the last centuries in both sequences is observed, likely related to increasing human pressure.
(CATENA. vol. 188, n° 0341-8162, pp. 104411, 01/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UiB
An assessment of reef coral calcification over the late Cenozoic
Shallow-water reef-building corals have an extensive geological record and many aspects of their evolution, biodiversity, and biogeography are known in great details. In contrast, the adaptive potential and risk of extinction of coral reefs in response to excessive warming and ocean acidification remains largely undocumented. It is well established that anthropogenic CO2 emissions cause global warming and ocean acidification (lowering of pH), which increasingly impede the biomineralization process in many marine calcareous biota. The “light-enhanced” calcification machinery of the shallow-water reef corals is particularly threatened by this development through the combined effect of a lowering of the supersaturation of seawater with CaCO3 (aragonite) and an expulsion of the symbiotic zooxanthellae (bleaching). The bleaching is of prime importance, because it interrupts the supply of DIC and metabolites required for pH upregulation within the calcification fluid. The degree of calcification in scleractinian reef corals may therefore represent a suitable tracer to assess the state of the ocean carbonate system and the photosynthetic performance of the zooxanthellae during past episodes of natural environmental change. This study presents the first comprehensive set of calcification data from corals covering the early Miocene to early Pleistocene interval (20.8 to 1.2 million years, Ma). Various screening procedures ensured that the studied coral skeletons are pristine and suited to yield meaningful stable isotope data (δ¹⁸O, δ¹³C) and calcification records. δ¹⁸O and δ¹³C values document growth environments consistent with current tropical and subtropical settings. To assess fossil calcification rates, we use a reference dataset of recent corals from the Indo-Pacific (Porites) and an independent validation dataset from the Western Atlantic-Caribbean (Orbicella). Almost all fossil corals document very low annual rates of upward growth (“extension rate”) relative to present, and lower skeletal bulk density than predicted by established modern relationships. To allow for a quantitative assessment of coral calcification performance, we use a new approach that we term the calcification anomaly. It is insensitive to sea-surface temperature and well-suited for comparative assessments of calcification performance between reef sites and over time. Based on this approach, the majority of fossil corals in our dataset displays hypo-calcification, while a few show optimal calcification and none display hyper-calcification. Compared to present-day growth conditions, the fossil calcification data show that (1) skeletogenesis responded in a fully compatible way to known environmental stresses (e.g. turbid water, elevated salinity, eutrophy), and that (2) the calcification performance within the reef window (i.e. oligotrophic clear-water settings) remained below that of modern z-corals. Since fossil coral δ¹³C values are compatible with those of modern reef corals, we infer that the light-enhanced calcification system of symbiotic scleractinian corals was fully established by the beginning of the Neogene and that lower-than-present calcification performance was the likely response to a chronically low pH and/or low carbonate saturation state of the global ocean. If so, the present-day saturation state appears to be rather an exception than the norm and probably not a suitable starting point for predicting future calcification trends. In addition, using trends from the geological past does not include anthropogenic side-effects such as eutrophication and pollution.
(Earth-Science Reviews. vol. 204, n° 0012-8252, pp. 103154, 01/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, HNHP, MNHN, UPVD, CNRS
Organic contaminants sorbed to microplastics affect marine medaka fish early life stages development
The role of polyethylene microplastics 4-6 mu m size (MPs) in the toxicity of environmental compounds to fish early life stages (ELS) was investigated. Marine medaka Oryzias melastigma embryos and larvae were exposed to suspended MPs spiked with three model contaminants: benzo(a)pyrene (MP-BaP), perfluorooctanesulfonic acid (MP-PFOS) and benzophenone-3 (MP-BP3) for 12 days. There was no evidence of MPs ingestion but MPs agglomerated on the surface of the chorion. Fish ELS exposed to virgin MPs did not show toxic effects. Exposure to MP-PFOS decreased embryonic survival and prevented hatching. Larvae exposed to MP-BaP or MP-BP3 exhibited reduced growth, increased developmental anomalies and abnormal behavior. Compared to equivalent water-borne concentrations, BaP and PFOS appeared to be more embryotoxic when spiked on MPs than when alone in seawater. These results suggest a relevant pollutant transfer by direct contact of MPs to fish ELS that should be included in the ecotoxicological risk assessment of MPs.
(Marine Pollution Bulletin. vol. 154, n° 0025-326X, pp. 111059, 01/05/2020)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LRHLR, HGS, IFREMER, GABI, INRAE, UMR MARBEC, IRD, IFREMER, UM, CNRS
Microplastic Contamination of Sediment and Water Column in the Seine River Estuary
Nowadays, microplastic (MPs) pollution is well documented in marine ecosystems since the first publication alarming about marine plastic pollution in 1972 [Carpenter, E.J., Smith, K.L.: Plastics on the Sargasso sea surface. Science 175, 1240–1241 (1972)]. Similarly, continental contamination is more and more investigated. More recently, interest for estuarine systems is growing. Estuaries are considered as a suspected predominant pathway for microplastic pollution from continent to oceans. The specific conditions of estuaries, like salinity gradient, tides and hydrodynamics, could affect the repartition, settling and transfer of microplastics to marine systems.
(pp. 4-9, 24/04/2020)
LEESU, ENPC, UPEC UP12, GERS-LEE, LERN, COAST, IFREMER, RDT, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Insights on Ecotoxicological Effects of Microplastics in Marine Ecosystems: The EPHEMARE Project
The Ephemare project was supported in the period 2015–2018 by JPI Oceans, as one of 4 sister projects in the joint action on ecological aspects of microplastics. Ephemare investigated several issues concerning the ecotoxicological effects of microplastics (MPs) in marine organisms. Ephemare included 16 European Institutions from 10 Countries and was organized into seven, highly complementary Work Packages (WPs) with the aim to elucidate adsorption and release of chemicals to/from MPs, coupled with MP ingestion rates, translocation in different tissues, trophic transfer and egestion, potential toxicological effects and mechanisms of action, as well as real distributions of MPs in marine organisms from several European areas.
(pp. 12-19, 24/04/2020)
UNIVPM, UAlg, UM, CNRS, IRD, IFREMER, UMR MARBEC, IRD, IFREMER, UM, CNRS, GU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GABI, INRAE, IAS, CNR, CIIMAR, UiO, UCC
Biological Clocks and Rhythms in Polar Organisms
Biological clocks are universal to all living organisms on Earth. Their ubiquity is testament to their importance to life: from cells to organs and from the simplest cyanobacteria to plants and primates, they are central to orchestrating life on this planet. Biological clocks are usually set by the 'beat' of the day-night cycle, so what happens in polar regions during the Polar Night or Polar Day when there are periods of 24 hours of darkness or light? How would a biological clock function without a time-keeper? This chapter details evidence that biological clocks are central to structuring daily and seasonal activities in organisms at high latitudes. Importantly, despite a strongly reduced or absent day night cycles, biological clocks in the Polar Night still appear to be regulated by background illumination. Here we explore evidence for highly cyclic activity, from behaviour patterns to clock gene expression, in copepods, krill and bivalves. The ultimate goal will be to understand the role of endogenous clocks in driving important daily and seasonal life cycle functions and to determine scope for plasticity in a rapidly changing environment.
(pp. 217-240, 09/04/2020)
CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Experimental ingestion of fluorescent microplastics by pacific oysters, Crassostrea gigas, and their effects on the behaviour and development at early stages
(Chemosphere, n° 0045-6535, pp. 126793, 01/04/2020)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Environmentally relevant mixture of S-metolachlor and its two metabolites affects thyroid metabolism in zebrafish embryos
(Aquatic Toxicology. vol. 221, n° 0166-445X, pp. 105444, 01/04/2020)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS
Facies associations, detrital clay grain coats and mineralogical characterization of the Gironde estuary tidal bars: A modern analogue for deeply buried estuarine sandstone reservoirs
Estuarine tidal bar sandstones are complex reservoir geobodies commonly exploited by the oil and gas industry. In order to better predict the reservoir potential of these geobodies, this study provides a modern-day reservoir analogue, describing tidal bars in the inner and outer Gironde estuary from the microscopic to the macroscopic scale.The originality of this work lies in the multi-scale study of modern estuarine tidal bars based on numerous piston cores extracted in a high-energy environment. This work demonstrates that these tidal bars are composite sedimentary bodies made up of individual reservoir sand units separated by thick muddy layers. Their vertical facies associations and internal architectures are controlled by local hydrodynamic variations and seasonal river influxes. Detrital clay grain coats are notably characterized using a portable and handheld mineral spectrometer from the base to the top of the tidal bars. X-ray diffraction and electron microscopes reveal that these coats are mainly composed of di-octahedral smectite, illite, chlorite and kaolinite associated with other components such as diatoms or pyrite. The best reservoir geobodies are those with the minimum clay permeability barriers at the macro and mesoscale. An optimum coated grain content and clay fraction volume is also needed for generating authigenic clay coatings and inhibiting quartz overgrowth. These conditions are met within the tidal sand bars of the outer estuary funnel that are expected to be the best reservoir geobodies in deeply buried sandstones.
(Marine and Petroleum Geology. vol. 114, n° 0264-8172, pp. 104225 (IF 3,538), 01/04/2020)
GEOPS, INSU - CNRS, CNRS, EGID, IC2MP [Poitiers], UP, INC-CNRS, CNRS, HydrASA, IC2MP [Poitiers], UP, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS