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We analyze whether ontogenetic diet change in Aegla uruguayana Schmitt, 1942 is related to the morphological changes in chelae and mandibles. We use a combination of scanning electron microscope (SEM) observation, dietary composition analysis (stomach observation, trophic niche amplitude, trophic overlap, and feeding strategy), and geometric morphometric tools (discriminant analysis and two-block partial least squares analysis). The two structures analyzed by SEM show differences between juvenile and adult specimens, both in their cuticle and morphology specializations. In juveniles, the absence of the lobular tooth is the notable feature. However, in adult sizes, it is marked development. Both groups have simple setae with infracuticular articulation and denticles with different arrangements between groups. In the incisive mandible process, the teeth and spines present sharper points in juveniles and considerable wear in adults. Aegla uruguayana presented two trophic strategies: a profile of more predatory traits when younger and mostly detritivorous when adults. The analysis of geometric morphometry substantiates the patterns observed in SEM and stomach contents analysis. The morphology of smaller specimens is associated with the consumption of animal items (ephemeropteran larvae and cladocerans), while the morphology of larger specimens is related to the consumption of plant remains. Key words: ecomorphology, niche breadth, geometric morphometry, ontogeny, anomuran, crab, Aegla uruguayana. Nous tentons d'établir si des modifications ontogénétiques du régime alimentaire chez le crabe d'eau douce Aegla uruguayana Schmitt, 1942 sont reliées à des changements morphologiques des chélipèdes et des mandibules. Nous utilisons une combinaison d'observations au microscope électronique à balayage (MEB), d'analyse de la composition du régime alimentaire (contenu stomacal, amplitude de la niche trophique, chevauchement trophique et stratégie d'alimentation) et d'outils de morphométrie géométrique (analyse discriminante et analyse des moindres carrés partiels à deux blocs). Les deux structures analysées par MEB présentent des différences entre les spécimens juvéniles et adultes, sur le plan des spécialisations tant de leurs cuticules que de leur morphologie. Chez les juvéniles, l'absence de la dent lobulaire est un élément notable, alors que chez les spécimens de taille adulte, son développement est marqué. Les deux groupes ont des soies simples avec une articulation infracuticulaire et des denticules dont la disposition diffère d'un groupe à l'autre. Dans le processus mandibulaire incisif, les dents et épines présentent des pointes plus acérées chez les juvéniles et une usure considérable chez les adultes. Deux stratégies trophiques ont été relevées chez A. uruguayana, à savoir: un profil de caractères plus étroitement associés à la prédation chez les individus plus jeunes et un profil principalement détritivore chez les adultes. L'analyse de la morphométrie géométrique corrobore les motifs observés par MEB et par l'analyse des contenus stomacaux. La morphologie de spécimens plus petits est associée à la consommation d'animaux (larves d'éphéméroptères et cladocères), alors que la morphologie des spécimens plus grands est associée à la consommation de restes de plantes. [Traduit par la Rédaction] Mots-clés: écomorphologie, largeur de niche, morphométrie géométrique, ontogenèse, anomoure, crabe, Aegla uruguayana., Introduction Energy acquisition is essential for individual survival, which is why diet has been a frequent focus of study. In many species, the morphology and behavior of prey capture and [...]

The hydrological regime is the main factor governing the functioning of floodplain rivers. A full comprehension of its dynamic leads to a better understanding of the system's behaviour. We analysed the daily water level of the Paraná River during the last century at three gauge stations using linear and non‐linear tools to characterise the hydrological dynamic and to analyse to what extent chaotic behaviour prevails. The three water level time series were characterised as non‐linear and non‐stationary by power spectrum, autocorrelation function, and surrogate test analyses. A strange attractor was developed when the phase space was reconstructed, having a low dimensional chaos supported by correlation dimension, positive maximum Lyapunov exponents, and recurrence quantification analysis. The sample entropy analysis shows that the system resulted unpredictable beyond a temporal threshold, and with an intermediate hydrological complexity, while Hurst exponent characterised it as persistent and with sensitive dependence on initial conditions. In a general overview, all the evidence obtained indicates that the Paraná River's behaviour is at the edge of chaos. A latitudinal gradient of decreasing chaoticity was observed as the floodplain extent increased, whereas complexity was highest at the intermediate river station due to the inflow of tributaries with different hydrology. This paper attempts to offer some additional insights for understanding the hydrological behaviour of floodplain rivers and the most appropriate methods to understand their complexity. [ABSTRACT FROM AUTHOR]

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

The paper presents an agent-based model reproducing a stylized credit network that evolves endogenously through the individual choices of firms and banks. We introduce in this framework a financial stability authority in order to test the effects of different prudential policy measures designed to improve the resilience of the economic system. Simulations show that a combination of micro- and macroprudential policies reduces systemic risk but at the cost of increasing banks' capital volatility. Moreover, the agent-based methodology allows us to implement an alternative meso regulatory framework that takes into consideration the connections between firms and banks. This policy targets only the more connected banks, increasing their capital requirement in order to reduce the diffusion of local shocks. Our results support the idea that the mesoprudential policy is able to reduce systemic risk without affecting the stability of banks' capital structure. [ABSTRACT FROM AUTHOR]