The life cycle of Ligula intestinalis, a pseudophyllidean cestode, was studstitute the hosts necessary for complete parasite development. In order to determine the actual species likely to be responsible for the very high level of parasitism observed, a two-year study was carried out. Our results show that the copepod Eudiaptonaus gracilis, the roach (Rutilus rutilus) and the great crested grebe (Podiceps cristatus) were the most favourable hosts for continuation of the parasite life cycle. The study shows how alterations exerted by infective larval stages of L. intestinalis affect the population dynamics of roach.

No abstract

No abstract

The seasonal determination of phytoplankton and zooplankton biochemical! composition indicated a maximal nutritional value in summer. Conversely, a decreasing of available quantity was observed in: autumn what implies an extension of dietary spectrum in the two species. In. summer, the interannual variability of population structure and available plankton biomass should explain the use:of energy reserves in fishes during that season.

El objetivo de este estudio es el análisis estructural, a todas las escalas, de la terminación occidental de la rama Norte de la Falla de Merens. En esta zona, afloran cuarcitas y pizarras pre-caradocienses intruidas por el granito de Soulcem. En su parte septentrional, dominan los pliegues tumbados, vergentes al Norte y con la foliación varisca S1 asociada, desarrollada con metamorfismo de grado medio, Mientras que al sur abundan pliegues variscos E-O, derechos y desarrollados en condiciones metamórficas de grado bajo. Ambos dominios están separados por la Falla de Merens, interpretada como una estructura Varisca con escaso juego alpino.