Benthic and Hyporheic Macroinvertebrate Distribution Within the Heads and Tails of Riffles During Baseflow Conditions

The distribution of lotic fauna is widely acknowledged to be patchy reflecting the interaction between biotic and abiotic factors. In an in-situ field study, the distribution of benthic and hyporheic invertebrates in the heads (downwelling) and tails (upwelling) of riffles were examined during stable baseflow conditions. Riffle heads were found to contain a greater proportion of interstitial fine sediment than riffle tails. Significant differences in the composition of benthic communities were associated with the amount of fine sediment. Riffle tail habitats supported a greater abundance and diversity of invertebrates sensitive to fine sediment such as EPT taxa. Shredder feeding taxa were more abundant in riffle heads suggesting greater availability of organic matter. In contrast, no significant differences in the hyporheic community were recorded between riffle heads and tails. We hypothesise that clogging of hyporheic interstices with fine sediments may have resulted in the homogenization of the invertebrate community by limiting faunal movement into the hyporheic zone at both the riffle head and tail. The results suggest that vertical hydrological exchange significantly influences the distribution of fine sediment and macroinvertebrate communities at the riffle scale

Sur un cas d'index varus bilatéral et congenital avec malformation de la 2e phalange

Mauclaire P., Roquejeoffre . Sur un cas d'index varus bilatéral et congenital avec malformation de la 2e phalange. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, VII° Série. Tome 7 fascicule 1-3, 1926. pp. 43-46

Ectrodactylie et syndactylie. Mains et pied fourchus

Mauclaire P., Bois . Ectrodactylie et syndactylie. Mains et pied fourchus. In: Bulletins de la Société d'anthropologie de Paris, IV° Série. Tome 5, 1894. pp. 123-158

Les angiomes

Port. a dúas tinta

Mud volcanoes as a window into the deep biosphere?

Mud volcanoes are often regarded as a source of geological information about the subsurface, through the mineralogical and/or isotopic composition of expelled mud, clasts and fluids. Here, we propose that mud volcanoes might also be considered as a window into the deep biosphere. We present results obtained using different methods to investigate microbial abundance and community structure. The microbial community structure in mud volcano sediments from Captain Arutyunov mud volcano on the Moroccan Margin was studied by fluorescent in situ hybridation (FISH) using four general oligonucleotide probes, targeting all organisms, Eubacteria, Archea, and sulphate reducers. Also, TOC and TC analyses of these sediments were measured, and the carbon and oxygen isotopic composition of carbonate crusts from a fault-bounded cliff in a nearby region was analysed.The total bacterial count of the samples averaged 1.2 10^8 cells per g of sediment, with the highest abundance at 10 cm below the sediment surface. This high density indicates that the mud volcano sediments are a suitable environment for microbial growth. This is confirmed by a relatively high percentage of hybridization obtained with the general probe, which showed that about 50% of the cells were metabolically active. The highest relative activity (62% at 10 cm below the sediment surface) also coincides with the highest abundance.The isotopic analysis has been carried out on separate components of a crust sample. The lithified carbonate matrix shows a carbon isotopic value of about -25‰. The other components, nonlithified mud, corals and bioclasts, display values of about -5‰. These results indicate that carbonate crust formation may occur within the methanogenesissulphate reduction transition zone (MST), which is located at a very shallow depth. This implies an upward migration of methane, possibly driven by fluid flow.Our results suggest that some of the microorganisms, present in the shallow subsurface on and around mud volcanoes, are brought to the surface together with fluids and/or mud breccia from the deep source layers. With further phylogenetic analysis of microorganisms living in mud volcano sediments and involved in the carbonate precipitation, we propose to identify some of these deep-dwelling organisms which are apparently able to adapt to a shallow sedimentary environment