Caractéristiques des particules fines sidérurgiques et impact sur la teneur en PM10 à une échelle locale

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Observations of the Diatoms Sceptronema orientale Takano and Tabularia parva (Kützing) D.M.Williams & Round on the Exoskeleton of Copepods in the English Channel and Coastal Celtic Seas

International audienceThe consortium of the epizoic diatom Sceptronema orientale Takano on living individuals of the harpacticoid copepod Euterpina acutifrons Dana was found in summer 2018 in the port of Brest, Celtic Seas, and in several locations of the open English Channel during the summer-autumn transition. Diatoms as epibionts on copepods remained unreported up to date in the region despite the high tradition of plankton observations. Tabularia parva (Kützing) D.M.Williams & Round was attached to the empty carapace of a copepod in the port of Brest. The detailed morphology is illustrated by scanning electron microscopy

Testing the vulnerability of juvenile sea bass (Dicentrarchus labrax) exposed to the harmful algal bloom (HAB) species Pseudo-nitzschia delicatissima

International audienceA 45-day exposure experiment was carried out to assess whether the harmful algal blooming Pseudo-nitzschia delicatissima (i.e. needle shaped diatom and potential domoic acid producer) is involved in recurrent mass mortality events at a coastal fish farm in the southern North Sea. Juvenile sea bass (Dicentrarchus labrax) were exposed to different concentrations of P. delicatissima, ranging from 1 × 106 to 5 × 106 cells L− 1. Despite exposure to high concentrations of P. delicatissima, sea bass weight and length based growth rates (0.05 ± 0.02 g d− 1 and 0.18 ± 0.05 mm d− 1, respectively) and condition (Fulton K = 0.98 ± 0.06 mg mm− 3) were not significantly reduced suggesting that the fish were not affected during the 45-day exposure period. However, signs of gill mucosa irritation (i.e. mucus overproduction) were observed, showing that this diatom induced a mechanical stress, which can affect gill functions or increase susceptibility of fish to secondary infections (e.g. bacterial and viral infections, parasitism). Results are discussed with regard to consequences for wild and farmed fish, and possible synergic noxious effects when P. delicatissima is associated with other potentially harmful taxa (e.g. Phaeocystis globosa) during the phytoplankton spring bloom in the eastern English Channel–North Sea ecosystem

Food preferences of larvae of Antarctic silverfish Pleuragramma antarcticum Boulenger, 1902 from Terre Adélie coastal waters during summer 2004

Ichthyoplankton samples were collected from 19 to 31 January 2004 in the Dumont d’Urville Sea (East Antarctic shelf). The Nototheniidae Pleuragramma antarcticum comprised more than 90 % of the sampled larvae. Gut contents of 95 P. antarcticum larvae were examined. Most larvae fed on phytoplankton, especially diatoms, whereas some other specimens had a mixed diet with phyto- and zooplankton prey. A single specimen fed exclusively on copepods. The stomach contents was dominated by three diatoms taxa, such as Thalassiothrix antarctica, Fragilariopsis spp. and Chaetoceros spp. Prey selection was apparently food density dependent, with an inverse relationship between food abundance and selection feeding. Larvae selected positively some diatoms, such as Coscinodiscus spp. and T. antarctica, presenting a low concentration in the water column compared to Fragilariopsis spp., which were strongly negatively selected. During summer, larvae were opportunistic feeders with a broad trophic niche, which allowed them to switch between different food types

Chemical characterization of industrial- and road traffic-influenced fine particles (PM0.3-2.5) and impact on xenobiotic metabolizing enzymes gene expression in human reconstituted airway epithelium

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Total mercury in marine species from the French coast of the Eastern English Channel

International audienceMercury (Hg) in fish can present a potential risk to wildlife and human consumers. Mercury levels were determined in 12 fish species and 2 invertebrate species from the French coast of the Eastern English Channel collected in June and November 2012. Total mercury concentrations in the muscle tissues ranged between 0.04 and 1.63 µg g-1 (d.w.). Dab and sandeel displayed a significant positive correlation between Hg concentrations and fish length. Seasonal differences in Hg concentrations were observed for dab and shrimp. The lesser weever showed significantly higher concentrations of Hg (0.97 ± 0.34 µg g-1 d. w.) than all other species. Gobies and sprat, which had the smallest size, showed significantly lower concentrations than herring, whiting, pout and sardine. Among the considered species, flatfish such as dab, flounder, plaice and sole displayed intermediate levels of Hg. In the present study, the fish age expressed as specimen length seems to be one of the major factors governing Hg contents in muscle tissues. Finally, mercury concentrations in commercial fish from the Eastern English Channel were below the levels fixed by the European Union for total mercury in edible parts of fish products

Brooding strategy of the Arctic cold seep polychaete Oligobrachia haakonmosbiensis

International audienceThe Arctic polychaete, Oligobrachia haakonmosbiensis (Family Siboglinidae) is the most abundant symbiotic species inhabiting the Haakon Mosby Mud Volcano (Norwegian Sea, depth 1250 m). Different aspects of gametogenesis, fecundity, embryogenesis and larval development were studied using biometric measurements, classical histology and scanning electron microscopy on specimens (n = 15) collected in July 2009 at two sites (72°00.28'N, 14°43.36'E; 72°00.33'N, 14°43.22'E). Several cohorts of oocytes, from oogonia to mature oocytes were observed in brooding females. Embryos with 16-64 cell divisions, trochophore and metatrochophore larvae, were found, in sequence, in female tubes, from just above the tentacles to the anterior end of the tube. Trochophores had both a prototroch and a telotroch; metatrochophores had an additional ciliary band, the neurotroch, but lacked a downstream feeding system. All of female reproductive stages, oocytes, embryos and larvae, were recovered in a single specimen suggesting the release of different batches of oocytes at least on the date of collection, which coincided with the boreal summer. Only one brooding female contained exclusively germ cells in the gonad suggesting a pause in reproduction. Fecundity was low: a maximum of 60 mature oocytes per female was counted, and if all the different stages of oocytes, embryos and larvae were combined, a total fecundity of ~250-300 propagules was found in each female. This study advances knowledge of the reproductive biology of O. haakonmosbiensis and has particular significance for understanding the distribution of this ecologically important deep-sea chemosymbiotic species in the Arctic region. The new data on life-history traits are critical for modeling, and predicting dispersal potential and connectivity among cold seeps in the Arctic, which is an essential component of marine spatial management

Chemical profile identification of fugitive and confined particle emissions from an integrated iron and steelmaking plant

International audienceThe aim of this study is to obtain the characteristic inorganic chemical profile of important particle sources identified in the integrated iron and steel process: sintering, blast furnace, steelmaking and desulfurization slag processing. A complete chemical and physical characterization program was developed: particle size distribution, chemical analysis, XRD, SEM-EDX and TGA/DTA. The sample collected from the sinter stack showed high levels of K and Cl(-), followed by Fe, NH4(+), Ca, Na and Pb. The profile of the dust samples taken from the sinter cake discharge zone was quite different, showing higher amounts of Fe, Ca and Al, and lower amounts of K, Cl(-), Na and Pb. Dust samples collected from the blast furnace (BF) and steelmaking cast house may be distinguished from each other based on the higher levels of Fe (hematite and magnetite) and lower levels of Ca, Zn and C (graphite) found in BF dust. High levels of Ca and Fe were found in samples taken from the desulfurization slag processing area. Such information can be useful for source apportionment studies at receptor sites that could be influenced by iron and steelmaking plant emissions

Larval growth of the polychaete Arenicola marina under different temperature and food conditions: consequences on bioenergetic models

International audienceAbstract Arenicola marina, a marine benthic polychaete, is widespread on sandy beaches in Europe and considered as an ecosystem engineer despite commonly used as bait by fishermen. Data regarding the bioenergetics of the lugworm larval stages are still incomplete. Trochophore is initially lecithotroph and then becomes planktotroph while growing as metatrochophore on subtidal area, a quite stable daily temperature environment compared with the foreshore, where juveniles and adult live, with daily temperature fluctuating up to 15°C. These discrepancies in temperature ranges may influence the temperature corrections (TCs) that control metabolic rates during the life cycle of A. marina. We carried out laboratory experiments in microcosms by inducing artificial spawning of lugworms, and then undertaken in vitro fertilization to obtain embryos and, finally, to follow, the larval development up to 10 segments with chaetae for 50 days under three temperature conditions (13°C, 15°C and 17°C) and two food conditions (‘fed’ and ‘non-fed’). The first feeding (‘birth’) of A. marina larvae was deciphered anatomically for a size between 450 and 500 μm and described at 17 days post-fertilization for larvae reared at 15°C and 17°C. Using a biphasic model with a von Bertalanffy growth before ‘birth’ and an exponential growth after ‘birth’, among the three temperature treatments, the 15°C condition exhibited the best larval performance. TC based on embryonic and larval metabolic rates gave an Arrhenius temperature of ~6661 K and a higher boundary temperature tolerance range of ~294.5 K. Both temperature values differ from those calculated from TC based mostly on juvenile and adult metabolic rates. We claim to use two sets of Arrhenius temperatures according to the life history stages of A. marina while using Dynamic Energy Budget model. This model was developed initially in order to manage the conservation of the lugworm species