• Neuroinformatics
• 14. Life underwater close

Dark littoral submarine caves can act as enclaves of the deep aphotic zone in shallow coastal areas, and their survey has revealed the existence of a very particular fauna of specialized and poorly known organisms among which crustaceans are particularly well represented. In these particular habitats, the use of conventional sampling techniques, such as hand nets, is often not recommended since they disturb bottom sediments causing hazardous situations to scientific divers. The use of baited traps, while technically possible, is not. always practical is such remote habitats. The present work describes a simple and inexpensive manual device that can be operated by divers ill submarine caves and other cryptic habitats to recurrently catch small motile organisms such as mysid crustaceans, caridean shrimps, or even gobiid fishes. This small suction bottle derived and improved from the original "Sket bottle" design considerably reduces the risks of disturbing the cave's bottom sediment and can be easily operated using a single hand. The described sampling device can also be easily used outside caves, in a variety of particular habitats, e.g., rubble filled bottoms, branching coral reefs, cracks, and small holes on rocky surfaces, in which small motile organisms usually escape from traditional sampling gears, e.g., fishnets and traps, or simply go unnoticed by researchers during sampling. info:eu-repo/semantics/publishedVersion

International audience; In the context of the severe decrease in temperate eel abundance, understanding and control of eel maturation has strong interest for scientific and commercial purposes. Possible use of ultrasonography for improvement of sex determination and maturation monitoring in silver eel was investigated. Gonads of 96 Anguilla anguilla silver eels were observed using portable equipment associated to a 6-15MHz probe, and sex determination was tried before artificial induction of maturation. To estimate gonad mass and monitor individual gonadosomatic index (GSI) in females, cross-sectional images were captured at different times of maturation and gonad length was measured at scanning. Two methods were tried for ovary mass estimation using ultrasonography: one based on a linear model and another on calculating ovary volume from a representation of gonad shape. Ultrasonography resulted in 100% success in sex determination. Ovary mass estimated by ultrasonography was strongly correlated to true ovary mass (R2=0.97). The use of a linear model for gonad mass and then GSI estimation seemed more appropriate than the use of a representation of gonad shape. Evolution of GSI estimates during maturation supports possible detection of early inter-individual differences in maturation using ultrasonography in female silver eels. This non-invasive tool can then obviously be exploited to improve sex determination in silver eels caught in the wild and to monitor maturation at the individual level. Ultrasonography thus has great potential for use in eel both for conservation and aquaculture. To our knowledge, this is the first report on the use of ultrasonography on eels or any anguillid species.

Summary1. Invertebrate bioturbation can strongly affect water‐sediment exchanges in aquatic ecosystems. The objective of this study was to quantify the influence of invertebrates on the physical characteristics of an infiltration system clogged with fine sediment.2. Two taxa (chironomids and tubificids) with different bioturbation activities were studied in experimental slow infiltration columns filled with sand and gravel and clogged with a 2 cm layer of fine sediment at the surface. We measured the effects of each taxon separately and combined on hydraulic head, water mobility and sediment reworking.3. The results showed that invertebrates could reduce sediment clogging and this effect was linked to the functional mode of bioturbation of each group. Tubificid worms dug networks of galleries in the fine sediment, creating pathways for water flow, which reduced the clogging of sediment. In contrast, the U‐shaped tubes of chironomids were restricted to the superficial layer of fine sediments and did not modify the hydraulic conductivity of experimental columns. The combination of invertebrates did not show any interactive effects between tubificids and chironomids. The occurrence of 80 tubificids in the combination was enough to maintain the same hydraulic conductivity that 160 worms did in monospecific treatment.4. The invertebrates like tubificid worms can have a great benefit on functioning of clogged interfaces by maintaining high hydraulic conductivity, which contributes to increased water‐sediment exchanges and stimulates biogeochemical and microbial processes occurring in river sediments.

Abstract In a first part, this paper describes radar experiments aimed at probing the sea surface from the coast. To capture small-scale changes in a coastal environment, a flexible high resolution, Doppler L-band radar with high resolution in range has been used. The data exhibit significant sensitivity to current and wind, which justifies the development of a model for inversion. The second part of the paper is thus devoted to our first attempt to model radar echoes, in order to accurately describe the influence of the geophysical parameters of interest. Here, the focus is put on waves generated by a local wind. The key point consists in taking properly into account non-linear hydrodynamic interactions between waves to generate a realistic moving sea surface. From the electromagnetic point of view, since standard low-frequency approximations no longer hold at L-band, a small-slope approximation has been implemented to compute the backscattered field. Numerical results show that for light winds (less than 5 m s −1 ) the model correctly predicts the behaviour of the data with respect to wind speed and direction. To cite this article: M. Saillard et al., C. R. Physique 6 (2005).

Abstract Crude extracts and semi-purified fractions (F5, F6) from the Mediterranean sea cucumber, Holothuria polii , collected from the bay of Tabarka (Tunisia coast) were evaluated for their antifungal activity against filamentous fungi and yeast. The activity was determined in vitro, using the well diffusion test in the casitone agar medium. Both the aqueous and the methanolic extracts were found to produce, in a concentration-related manner (600–1500 μg/well) a significant antifungal activity. The semi-purified fractions (F5, F6) of both extracts exhibited also a significant antifungal activity in a concentration-related manner (150–300 μg/well). The strains of Aspergillus fumigatus were more susceptible to these extracts and derived fractions, while those of Trichophyton rubrum were found to be less susceptible. No activity was observed against strains of Candida albicans . These findings suggest that the polar active fractions (F5, F6) obtained from aqueous and methanolic extracts could contain a new antifungal compound(s). The purification and the determination of chemical structure of compound(s) of these active fractions are under investigation.

International audience; The Mediterranean Sea Coast is subject to strong anthropogenic pressure because of an intensification of urban, industrial, agricultural and tourist catchment (UNEP, 2000). This anthropogenic pressure is reflected in the direct (from coastal sources) and indirect (via rivers) discharge of terrigenous materials and pollutants (Tolosa et al., 1996; UNEP, 1996). These contributions promote transformations of ecosystems and associated biogeochemical cycles. In order to assess environmental changes, discrete measurements at fixed observation site (i.e. SO-COM, SOMLIT station) are useful but remain insufficient to describe the synoptic extension and the impact of these released terrigenous inputs. An objective of the laboratory is to develop and use in situ UV fluorimeters for quantification at high spatial and temporal frequency of terrigenous and anthropgenic tracers such as polycyclic aromatic hydrocarbons (PAHs, index of chemical contaminations) and "tryptophan-like" material (index of bacterial contaminations). An in situ UV fluorometer (EnviroFlu-HC, TriOS optical sensor) was deployed in the coastal area of Marseille-Sud since January 2008. The fluorescence signal of this probe (Ex/Em: 254±25 / 360±50 nm) was compared to the spectrofluorimetric Excitation Emission Matrices (EEMs) of discrete samples taken from the same area. The probe signal, due to its relative "large" Excitation and Emission bands, covers the EEMs signature of several groups of compounds: PAHs, tryptophan-like material, humic substances. This study is part of a laboratory program that aims at developping observation tools for operational oceanography and urban marine zone management: The project SEA EXPLORER (leader ACSA-Meyreuil, partnerships: ACRI, ISITIV, IFREMER, LMGEM-COM, LOV) funded by the Ministery of Industry (Fond de Compétitivité des Entreprises, FCE). Other partners: Agence de l'Eau Rhône-Méditerranée (IBISCUS project).

Long-term evolutions of wave orientation are important parameters that explain shoreline evolutions and coastal risks. Within the DISCOBOLE project (Donnees pour le dImensionnement des Structures Cotieres et des Ouvrages de BOrd de mer a Longue Echeance), the lack of record of this parameter along the Channel and Atlantic French coasts requires to identify geomorphological features (geomorphological indicators) that indicate wave orientations and evolutions during the last decades. Within this aim, the evolutions of the axis of trailing spits, tombolos and cuspate beaches and beach rotations are analysed over the last decades by mean of present and old aerial photographs and maps. Alterning periods of meridian and zonal orientations are then identify. From 1979 to 2003, results are compared to the data obtained in the EDF-LNHE numerical atlas of waves.

International audience; Seasonal variations of six mussel (Mytilus galloprovincialis) biomarkers at two sites in the Mediterranean Sea were compared with physiological indices (condition, growth and gonad maturation), environmental parameters (temperature, salinity and turbidity), and chemical contamination levels. The basal levels of acetylcholinesterase (AChE), DNA adducts, benzo[a]pyrene hydroxylase (BPH), heat-shock proteins (HSP70), metallothioneins (MT) and P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) were estimated as early warning signals in caged mussels sampled at Carteau (native site) and La Fourcade (transplantation site) over a 2-year period. The Carteau and La Fourcade mussels have specific chemical contamination profiles but a similar range of values. For example, both are highly contaminated by heavy metals (201 and 258.4 mg kg−1 dw, respectively) and considered as moderately impacted for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). However, contamination levels at Carteau are twice as high for PAHs (101.5 mg g−1 dw) and PCBs (90.2 mg g−1 dw) than La Fourcade. The seasonal contamination trend at Carteau showed six-fold higher levels of pyrolytic pollutants in winter. Although few tissue lesions were detected in individuals studied at either site, greater parasitic infestation was observed at Carteau. The results of findings from the two Mediterranean pilot studies support the adaptability of transplanted mussels to be used as biomarkers and to establish physiological endpoints for chemical contaminant exposure.