Dredging and sediment discharge in a river with floodplain. Physicochemical and microbiological effects in Paraná river.

Alterations caused by human activities in the environment, such as dredging, modify the physicochemical conditions and affect the habitat. Maintenance dredging that allows large vessels access to inland ports is a recurring disruptive action. The study aimed to evaluate, during a maintenance dredging operation in a port area of the Paraná River, the modifications in the structure of the river, the presence of contaminants and bacterial organisms.

Functional morphology of comminuting feeding structures of Trichodactylus borellianus (Brachyura, Decapoda, Trichodactylidae), an omnivorous freshwater crab.

Crustaceans exhibit great diversity of feeding structures with morphological traits that are useful to infer the general trophic habits of species. In this study, we analyzed the functional morphology of comminuting feeding structures (mandibles, chelipeds, gastric mill) of the freshwater crab Trichodactylus borellianus directly related with the food fragmentation. The heterochely and mechanical advantage (MA) of the chelae were also studied.

Morphological variation of freshwater crabs Zilchiopsiscollastinensis and Trichodactylusborellianus (Decapoda, Trichodactylidae) among localities from the middle Paraná River basin during different hydrological periods.

Measures of hydrologic connectivity have been used extensively to describe spatial connections in riverine landscapes. Hydrologic fluctuations constitute an important macrofactor that regulates other environmental variables and can explain the distribution and abundance of organisms. We analysed morphological variations among individuals of two freshwater crab species, Zilchiopsiscollastinensis and Trichodactylusborellianus, from localities of the middle Paraná River basin during two phases of the local hydrological regime.

Trophic ecology of the freshwater prawn, Pseudopalaemon bouvieri (Decapoda: Palaemonidae) in Northeastern Argentina, with remarks on population structure.

Freshwater decapod crustaceans are important components of food webs in these environments, but little is known about the diet of species that live in tropical waters. We studied the feeding ecology of the prawn Pseudopalaemon bouvieri and its population structure in two different areas with six lagoons, with a different composition and abundance of aquatic macrophytes. At each site of macrophytes banks, 18 prawns sample was collected with a hand net (1mm mesh size) from 1m2.