Patterns of silver eel (Anguilla anguilla L.) sex ratio in a catchment

Changes in the numbers and size-class structure of European silver eels, Anguilla anguilla, in the River Fre´mur (France) were examined over a 9-year period after installation of downstream eel passes. The number of silver eels migrating downstream peaked in 1999, then decreased strongly and steadily after 2000, reaching relatively low levels. At the same time, a gradual shift in the silver eel sex ratio from a dominance of males (size from 270 to 442 mm, age from 3 to 6 years) to females (size from 366 to 1112 mm, age from 4 to 9 years) was recorded. Possible explanations for the escapement patterns observed are environmental sex determination and the installation of eel passes on the main hydraulic engineering structures in 1992 and 1996

Instauration Et Conservation De La Biodiversite Des Espaces Verts Dans L’arrondissement De Lobogo (Commune De BOPA)

Résumé                                                         Les ressources végétales constituent pour la population d’importantes sources de soins médicaux, de repos, de commerce et d’aliments puis ont une valeur esthétique, touristique et écologique dans une ville. Cette recherche est une contribution à une meilleure compréhension de la notion de la foresterie urbaine, de son importance dans une ville et pour ses habitants ; elle ne veut non pas qu’étudiée les espaces verts existants : elle se veut influencer la décision des différents acteurs, excité les autorités à divers niveaux à prendre des décisions écologiques.La collette des données a été fait à travers la recherche documentaire, les enquêtes de terrain auprès des différents acteurs arboricoles, le traitement statistique des données par le tableur Excel 2013 et l’analyse des résultats a aussi été fait à l’aide du modèle EPIR constituent la démarche méthodologique adoptée.  Les résultats obtenus indiquent que l’Arrondissement de Lobogo dispose des potentialités pour l’instaurer et conserver la biodiversité des espaces verts. Le régime pluviométrique (deux saisons avec entre 1200 et 1300 mm), la température varie entre 23°C (valeur minimale) et 32,5°C (valeur maximale), l’humidité qui varie entre 75,9 % (valeur minimale) et 84 % (valeur maximale), le réseau hydrographique, les facettes pédologiques (sols hydromorphes, sols ferrugineux tropicaux etc.), les activités économiques (agriculture et commerce) et la croissance démographique (14385 habitants en 1992 contre 20467 en 2013). De plus, 17,1 % de la population enquêtée estiment qu’ils vont faire des jeux dans les espaces verts, 41,44 % pensent y vont pour se reposer. 35,52 % y vont pour faire de commerce et 5,92 % font des espaces verts de l’espace ornemental, du jardin et d’espace médicinal. Bien que ces espaces verts soient d’une utilité importante, il ressort que 56,52 % pensent que l’entretien des espaces est mauvais ; de même, 36,84 % ont dit que l’entretien est moyen. Cependant, 1,97 % ont estimé que l’entretien est médiocre. Par contre, 2,63 % ont constaté que ces espèces sont bien entretenues. Du reste, face à ces contraintes que font face les espaces verts, il n’y a pas une coordination des actions entre les différents acteurs impliqués dans l’instauration et conservation des espaces dans l’Arrondissement de Lobogo. Aussi, le budget alloué à ceci est insignifiant et le peu est mal géré ou détourné.Mots clés : Les ressources végétales ; biodiversité ; l’Arrondissement de Lobogo ; la foresterie urbaine. AbstractPlant resources are important sources of medical care, rest, commerce and food for the population, and then have esthetic, tourist and ecological value in a city. This research is a contribution to a better understanding of the notion of urban forestry, of its importance in a city and for its inhabitants; it does not want the existing green spaces to be studied: it wants to influence the decisions of the various actors, and to stimulate the authorities at various levels to make ecological decisions.The data was collected schow documentary research, field surveys with the various arboricultural stakeholders, the statistical processing of the data by the Excel 2013 spreadsheet and the analysis of the results was also done using the EPIR model constitute the methodological approach adopted.The results obtained show that Lobogo District has a potential for establishing and conserving the biodiversity of green spaces. The rainfall regime (two seasons with between 1200 and 1300 mm), the temperature varies between 23 ° C (minimum value) and 32.5 ° C (maximum value), the humidity which varies between 75.9 % (minimum value) and 84% (maximum value), the hydrographic network, the pedological facets (hydro-morphic soils, tropical ferruginous soils etc.), economic activities (agriculture and trade) and population growth (14,385 inhabitants in 1992 against 20,467 in 2013). In addition, 17.1 % of the surveyed population believe that they go to play in green spaces, 41.44 % think they go there to rest. 35.52 % go there to trade and 5.92 % make green spaces for ornamental space, the garden and medicinal space. Although these green spaces are of great use, it appears that 56.52 % think that the maintenance of the spaces is bad; similarly, 36.84% said the interview was average. However, 1.97% rated the interview as poor. On the other hand, 2.63% found that these species are well maintained. Moreover, faced with these constraints faced by green spaces, there is no coordination of actions between the different actors involved in the establishment and conservation of spaces in the Lobogo district. Also, the budget allocated to this is insignificant and the little is poorly managed or misappropriated.Keywords: Plant resources; biodiversity; Lobogo District; urban forestry.         

Utilisation de levures sélectionnées et biodiversité

Trata-se de uma tradução do artigo "Selected yeast utilization and biodiversity", que foi publicado na revista "Cahier des Entretiens Scientifiques" da empresa multinacional Lallemand. A correspondente comunicacao foi apresentada no âmbito do encontro científico "XVII Entretiens Scientifiques Lallemand" (Logorno, Espanha, 25.4. – 28.4.2005). Cet article a été adapté d’une récente publication, Valero et al., FEMS Yeast Research, 2005, in press. Cette étude a été soutenue financièrement par la subvention n° 657 C2 de l’accord de coopération entre l’Institut Portugais de la Coopération Scientifique et Technologique (ICCTI) et l’ambassade Française à Lisbonne ainsi que la bourse de recherche Marie Curie du programme de la Communauté Européenne « Qualité de vie et gestion des ressources du vivant », dont le n° de contrat est le QLK4-CT-2001-51873. Les auteurs souhaitent remercier D. Delteil de l’ICV de Montpellier pour l’aide qu’il nous a apportée dans la sélection des sites d’échantillonnage en France, les œnologues des caves Portugaises (R. Cunha, A. Mendes, E. Rodrigues et J. Domingues) et également les oenologues (B Agay, E. Feneuil et E. Bru) et directeurs (J. L. Refle, J. Combette et R. Bruno) des caves Françaises, qui ont facilité les campagnes d’échantillonnage dans les vignobles

Are Amphipod invaders a threat to the regional biodiversity? Conservation prospects for the Loire River

The impact of invasions on local biodiversity is well established, but their impact on regional biodiversity has so far been only sketchily documented. To address this question, we studied the impact at various observation scales (ranging from the microhabitat to the whole catchment) of successive arrivals of non-native amphipods on the amphipod assemblage of the Loire River basin in France. Amphipod assemblages were studied at 225 sites covering the whole Loire catchment. Non-native species were dominant at all sites in the main channel of the Loire River, but native species were still present at most of the sites. We found that the invaders have failed to colonize most of tributaries of the Loire River. At the regional scale, we found that since the invaders first arrived 25 years ago, the global amphipod diversity has increased by 33% (from 8 to 12 species) due to the arrival of non-native species. We discuss the possibility that the lack of any loss of biodiversity may be directly linked to the presence of refuges at the microhabitat scale in the Loire channel and in the tributaries, which invasive species have been unable to colonize. The restoration of river quality could increase the number of refuges for native species, thus reducing the impact of invader

Jumping performance in the highly aquatic frog, Xenopus tropicalis : sex-specific relationships between morphology and performance

Frogs are characterized by a morphology that has been suggested to be related to their unique jumping specialization. Yet, the functional demands associated with jumping and swimming may not be that different as suggested by studies with semi-aquatic frogs. Here, we explore whether features previously identified as indicative of good burst swimming performance also predict jumping performance in a highly aquatic frog, Xenopus tropicalis. Moreover, we test whether the morphological determinants of jumping performance are similar in the two sexes and whether jumping performance differs in the two sexes. Finally we test whether jumping capacity is positively associated with burst swimming and terrestrial endurance capacity in both sexes. Our results show sex-specific differences in jumping performance when correcting for differences in body size. Moreover, the features determining jumping performance are different in the two sexes. Finally, the relationships between different performance traits are sex-dependent as well with females, but not males, showing a trade-off between peak jumping force and the time jumped to exhaustion. This suggests that different selective pressures operate on the two sexes, with females being subjected to constraints on locomotion due to their greater body mass and investment in reproductive capacity. In contrast, males appear to invest more in locomotor capacity giving them higher performance for a given body size compared to females

Migration pattern of silver eel (Anguilla anguilla, L.) in an obstructed river system.

The downstream migration of European silver eels in the River Frémur was examined to determine the potential effects of the numerous migration barriers that exist on waterways in western France. The Frémur has a 14 m high dam which creates a 3 · 106 m3 water supply reservoir, 6 km from tidal limit. Based on 8-year records (1996–2004) of migrant silver eels captured in a Wolf trap located about 1 km below the dam, the influence of this dam on the migration was examined. These records indicate that 91% of silver eels were captured when the dam was overtopped (i.e. when the water reservoir was full). The timings of the overflow periods varied greatly between years mainly because they are function of the duration of the filling period which in turn is dependent on the level of summer water abstraction and annual hydrological conditions. Consequently, migration periods occurred at variable dates (between November and April) which is late in comparison with nonobstructed European river systems (generally between August and December). During overflow periods the migration of silver eels increased markedly during rain events (increasing river flow). This indicates that flow flushes, are essential so that settled silver eels can orientate themselves and pass over the dam. The hypothesis of a ‘dam effect’ that could stop temporarily or permanently some of silver eels in the reservoir is discussed. Finally, the influence of the migration delays on the condition of silver eels is considered

Does the invasive plant Elymus athericus modify fish diet in tidal salt marshes?

The invasion of Mont-Saint-Michel Bay salt marshes (France) by a grass species (Elymus athericus) has led to important changes in vegetation cover, which is likely to modify the habitat for many invertebrates. Some of them constitute the main food items for several fish species, such as young sea bass (Dicentrarchus labrax) and sand goby (Pomatoschistus minutus), that feed in salt marsh creeks during high tides. As a result, fish nursery functions of salt marshes could be modified by the E. athericus invasion. In order to test this hypothesis, gut contents of the two most abundant fish species (sea bass and sand goby) were compared before and after E. athericus invasion in the same salt marsh creek and using the same methodology. The accessibility and availability of the main food item, the semi-terrestrial amphipod Orchestia gammarella, were estimated and compared between invaded (dominated by E. athericus) and original areas (dominated by Atriplex portulacoides). Gut content analysis showed a significantly greater percentage of fish leaving with empty guts from E. athericus areas than from A. portulacoides areas. The sea bass diet composition study showed a major shift in the relative importance of the main food items: before E. athericus invasion, diets were dominated by the semi-terrestrial species O. gammarella, whereas after the E. athericus invasion they were dominated by a marine mysid Neomysis integer. The same trend was found for sand gobies, with a shift of the main food item from O. gammarella before invasion to the polychaete Hediste diversicolor after invasion. These trophic changes may be explained by the lower accessibility and availability of O. gammarella in invaded communities than in natural ones. The E. athericus invasion, observed throughout northern Europe, is thus likely to disturb trophic function of natural salt marshes for fish. This preliminary study of the E. athericus invasion is also an illustration that invasive species are an urgent problem in conservation biology