Thermodynamique des systèmes micellaires : Partie II - Volumes molaires apparent et partiel des alcanoates de sodium selon la méthode de la pseudo-phase (MPP)

Thermodynamics of micellar systems : Part II - Apparent and partial molar volumes of sodium alkanoates according to the pseudo-phase model (MPP)Volumetric measurements were carried out to obtain the apparent and partial molar volume of the aqueous solutions of the homologous series of sodium alkanoates from formate (n=0) to undecanoate (n=10). The results are analysed according to the pseudophase method (MPP). Three areas are defined corresponding to “the authentic solutions, micro-heterogeneity and pseudo-phase”. Then the critical micellar concentrations of products were obtained and the variations of the apparent and partial molar volumes during the micellization were determined. This method permits also to evaluate different micellar properties.  

Thermodynamique des systèmes micellaires Partie 1 : Volumes molaires apparent et partiel des alcanoates de sodium selon le modèle d’action de masse (MAM)a

Thermodynamics of micellar systems Part I : Apparent and partial molar volumes of sodium alkanoates according to the mass-action model (MAM)Densities of the homologous sodium caboxylates were measured with a flow densimeter. Results were analysed according to the mass-action model. The first and some times the second micellar critical concentrations were determined. The apparent and partial molar volumes were calculated as well as the excess volumes. The solute-solute and solute solvent interactions were discussed

Diet and feeding habitats of camargue dabbling ducks: What has changed since the 1960s?

In the Camargue (southern France), drastic changes in wetlands have occurred (notably extension of agriculture and salt extraction) since the 1960s, which affect the resources available to migratory waterbirds. Winter diets of Mallard (Anas platyrhynchos) and Teal (A. crecca) in 2006-2008 were assessed by analyses of gullet contents. Using PCA-based methods, duck diets were described and the main feeding habitats used by each duck species were then determined with a typology analysis. The same four food items were most important (in terms of occurrence and average dry weight) in the diet of Mallard and Teal: Oryza sativa (rice), Echinochloa sp., Scirpus maritimus and Potamogeton pusillus seeds. However, Teal diet was more diversified, with eleven feeding habitat types, compared to only five in Mallard. Both species were found to be dependent on ricefields and ricefield-like habitats. Compared to previous studies in the same area between 1964 and 1981, permanent freshwater habitats now appear to be used more intensively by Mallard and Teal, while temporary marshes are used to a lesser extent. Since the 1960s, temporary marshes have been partially replaced by permanent freshwater in order to attract more ducks, mostly for hunting. The flexibility of duck diet in response to changing food availability may explain why duck populations have not decreased in the Camargue or in Europe despite changes in land use.Peer Reviewe

The Apparently Relentless Spread of the Major Decapod Alien Species in the Mediterranean Basin and European Inland Waters

Among the many alien crustacean species so far recorded in the Mediterranean basin are numerous decapods\u2014crayfish, crabs and prawns\u2014that have in common the reputation of being both aggressive and adaptable to various environments. Their entrance to the Mediterranean basin has often been fostered by human actions, such as the transfer of new species for commercial purposes or accidentally, as bycatch or because they were present in discarded ships\u2019 ballast water. Marine alien species enter the Mediterranean basin from two main directions: from the Atlantic and beyond, and from the Indian Ocean via the Suez Canal. For freshwaters, the extensive European canal network is an important aid to migration, but human discards are also significant. Protection of native fauna and ecosystems is at best partial. Freshwater ecosystems particularly at risk include lagoons, river estuaries, ponds and marshes, while comparable marine systems are shallow muddy coastal regions, rocky reefs, estuaries/bays and salt marshes. Local communities, principally anglers and people working with aquatic resources, usually are curious at the appearance of a new species and the possibility of establishing a new business is often the first thought. However, freshwater decapod alien species cause major damage to agriculture production, infrastructures, riverbanks, irrigation systems and fish production, leading to consistent economic losses. In particular, they are known to be injurious to plant production, causing increasing losses to agriculture, consuming young seedlings and seeds and causing substantial water losses from field areas. Less information is available for seawater species to date, but their increasing number and growing size of populations requires the attention of the scientific community to evaluate and predict their influence on the marine environment and/or on local fish and bivalve production. Both freshwater and marine alien decapods thus represent a serious threat to native European species and have a negative impact on species richness and habitats. The economic losses caused by these species require reliable and cost-effective options for managing their abundance and if possible for their eradication