Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin

Background: In inland water systems, it is important to characterize the trophic links in order to identify the ‘trophic species’ and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours. Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs. Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro- and microfauna.Fil: Williner, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: de Azevedo Carvalho, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentin

Prédictibilité de la réponse hémodynamique lors du remplissage vasculaire par la pression veineuse centrale (PVC), la variation de la pression pulsée et la variation de la pression systolique chez les patients de réanimation en défaillance circulatoire aiguë

MONTPELLIER-BU Médecine UPM (341722108) / SudocPARIS-BIUM (751062103) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Benthos of a large neotropical river: spatial patterns and species assemblages in the Lower Paraguay and its floodplains

We studied the composition and spatial structure of benthic invertebrate assemblages and their physical and chemical environment on a 331 km long section of the Lower Paraguay River between Asunción (Paraguay) and the river's confluence with the Parana River near Corrientes (Argentina). Applying the same methods used in former studies in the Upper Paraguay and Parand Rivers, we sampled bottom fauna, bed sediments and water at ten riverine stations, two tributaries, and six floodplain lake sites. Seventy-six taxa, mostly oligochaetes (18 species) and chironomids (17 species), were identified. There was a clear distinction between central sites, river banks, and floodplain habitats. Highly significant regressions between sediment composition and biotic parameters were obtained (clay/diversity, R = 0.60, p <0.0001; silt/diversity, R = 0.61, p <0.0001; organic matter/diversity, R = 0.63, p <0.0001; coarse-middle sand/density, R = 0.75, p = 0.001). Central channel sites were dominated by the psammophilous oligochaete Narapa bonettoi, which attained densities of 10-3,500 ind. m⁻². The river banks had higher diversity indices, but lower average densities than the main channel center. Some sites with solid substrates were densely colonized by an invading mollusk species, Limnoperna fortunei, which had maximum densities of 13,500 ind. m⁻². Diversity was highest in the floodplain lakes (Shannon's H = 2.4 ± 0.67) compared with banks (H = 1.79 ± 0.77) and central sites above the confluence of the Bermejo River (H = 0.89 ± 0.35). This tributary carries large amounts of fine sediments and organic matter into the Paraguay River, thereby reducing biodiversity and abundance of Narapa bonettoi. The faunal composition of the Lower Paraguay was more similar to that of the Middle Parand than to that of the Upper Paraguay. From this and former studies, two general patterns of river ecology become apparent: 1) naturally flowing sand-bed rivers can have continuous species assemblages over very long distances, characterized by few, well-adapted species that occur in high densities, but contribute relatively little biomass to the riverine foodweb; and 2) the biodiversity in the floodplain water bodies is higher than in the river channel as a result of the greater habitat diversity