West African rivers as biogeographic islands : species richness of fish communities

Some factors influencing the species richness of West African fish communities were studied in a sample of 26 rivers using four habitat and hydrologic variables. Analysis of a larger sample of 39 rivers showed that species richness was positively related to area. A power function with an exponent of 0.32 gave the best fit. As the surface area used was that of the catchment area and not that (unknown) of the river, the biological significance of this relationship and the possibilities of comparison were limited. Ridge regression analysis and forward stepwise selection indicated that a model that explained ln (species richness) as a function of ln (mean annual discharge) and ln (catchment surface area) was best, accounting for 90% of the variance of the dependent variable. (D'après résumé d'auteur

Geographic range of West African freshwater fishes : role of biological characteristics and stochastic processes

Une étude de l'amplitude de répartition géographique des poissons d'eau douce de la zone sahélo-soudanienne en Afrique de l'Ouest a été entreprise. L'amplitude de répartition géographique d'une espèce est définie ici comme le nombre de rivières où cette espèce est présente. La distribution de fréquence des amplitudes de répartition géographique est bien décrite par une fonction puissance négative. Un modèle stochastique où toutes les espèces sont supposées avoir les mêmes probabilités d'extinction dans chaque rivière et les mêmes probabilités d'immigration d'une rivière à l'autre est développé afin de tester la possibilité de reconstituer une distribution de fréquence proche de celle observée. Pour certaines valeurs des paramètres on obtient des distributions de fréquence auxquelles il est possible d'ajuster une fonction puissance négative, mais dans tous les cas la dispersion de l'amplitude de répartition du modèle est inférieure à celle observée. (D'après résumé d'auteur

Freshwater fish zoogeography in West Africa : faunal similarities between river basins

Similarities between the freshwater fish faunas of 52 West African rivers have been investigated and three main zoogeographic regions recognized. The Sudanian region includes all rivers from Senegal to the Omo, as well as coastal basins from Ivory Coast to the Cross and the Wouri. The upper Guinean region comprises the coastal basins from Guinea to Liberia and the Lower Guinean one, the coastal rivers of Cameroon and Gaboon. The Sudanian region can be sub-divided into a Sudanian region sensu stricto, including the Sahelo-Sudanese rivers, and the Eburneo-Ghanean region corresponding to coastal basins from the Cess (or Nipoué, Ivory Coast) to the Pra (Ghana). These delimitations give an highly significant within region faunal homogeneity, even if the effect of geographical proximity between rivers is removed. 21 to 71% of the fish species in each regions are endemics. The present patterns of distribution are the result of past climatic and geological events affecting West Africa and, given this framework, the role of alternating wet and dry periods during the early quaternary is emphasized as well as the importance of mountains as dispersal barriers. Role of recent river connections and links via lagoon is emphasized in explaining river faunal similarities within biogeographical regions. (Résumé d'auteur

Biogéographie et structure des peuplements de poissons d'eau douce de l'Afrique de l'ouest : approches quantitatives

SIGLEINIST T 73051 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Молитовний напис Брячислава Святополковича з Софії Київської

У статті висвітлюються результати дослідження молитовного напису, що знаходиться на фресці з образом Св. Анни в центральній наві Софії Київської. Встановлено, що графіті виконане сином київського князя Святополка Брячиславом у 1110–1113 роках. Встановлено, що Павло було християнським ім’ям Брячислава, й цей факт, разом із аналізом інформації літописної статті 6612 р., дозволив визначити вірогідну дату народження князя, окресливши її 15-м січня 1105 р.Статья посвящена публикации результатов исследования молитвенной надписи, находящейся на фреске с образом Св. Анны в центральном нефе Софии Киевской. Установлено, что граффити выполнено сыном киевского князя Святополка Брячиславом в 1110–1113 гг. В процессе анализа текста было определено, что Павел было христианским именем Брячислава, и этот факт, вместе с анализом летописной статьи 6612 г., позволил определить вероятную дату рождения князя, отнеся ее к 15 января 1105 г.The article deals with the results of investigation of prayer inscription located on the fresco with the image of St. Anna Sophia in the central nave of Kyiv St. Sophia Cathedral. It is determined that graffi ti was done by Bryachyslav, the son of the Grand Prince Svyatopolk, in 1110– 1113. The comparison mentioned in graffi ti Bryachyslav’s Christian name – Pavlo (Paul), with chronicles’ information by 6612 shows that the 14th or 15th of January 15 in 1105 is the likely date of Bryachyslav’s birth

Non-interactive fish communities in the coastal streams of North-western France

1. Spatial patterns of freshwater fish species at regional and local scales were investigated to explore the possible role of interspecific interactions in influencing distribution and abundance within communities occupying coastal streams of North-Western France. 2. Nine sites from nine streams situated in the same biogeographical region were sampled annually over the 6-year period from 1990 to 1995. 3. Similar habitats (sites) with richer regional colonization pools exhibited proportionally richer local communities in terms of number of species, total density and total biomass of individuals. Furthermore, no negative relationships were found between density and biomass of each of the most common species and local species richness. 4. Results of dynamic regression models (applied to the above-mentioned species) suggest an absence of strong competition between all pairs of species. 5. The evidence on lack of density compensation for species-poor communities and absence of perceptible interspecific competition between species suggest that the communities studied are non-interactive. 6. Two main explanations can be advanced. First, the local abundance of species in the communities studied could be determined through differential responses to unpredictable environmental changes, rather than through biological interactions. Second, as a result of historical events, the communities studied are reduced in congeneric species which can limit, in turn, the influence of interspecific competition in structuring these communities. 7. These results underline the strong influence of regional processes in shaping local riverine fish communities and minimize the possible influence of species interactions in governing these communities

Non-interactive fish communities in the coastal streams of North-western France

1. Spatial patterns of freshwater fish species at regional and local scales were investigated to explore the possible role of interspecific interactions in influencing distribution and abundance within communities occupying coastal streams of North-Western France. 2. Nine sites from nine streams situated in the same biogeographical region were sampled annually over the 6-year period from 1990 to 1995. 3. Similar habitats (sites) with richer regional colonization pools exhibited proportionally richer local communities in terms of number of species, total density and total biomass of individuals. Furthermore, no negative relationships were found between density and biomass of each of the most common species and local species richness. 4. Results of dynamic regression models (applied to the above-mentioned species) suggest an absence of strong competition between all pairs of species. 5. The evidence on lack of density compensation for species-poor communities and absence of perceptible interspecific competition between species suggest that the communities studied are non-interactive. 6. Two main explanations can be advanced. First, the local abundance of species in the communities studied could be determined through differential responses to unpredictable environmental changes, rather than through biological interactions. Second, as a result of historical events, the communities studied are reduced in congeneric species which can limit, in turn, the influence of interspecific competition in structuring these communities. 7. These results underline the strong influence of regional processes in shaping local riverine fish communities and minimize the possible influence of species interactions in governing these communities

Applying an index of biotic integrity based on fish assemblages in a west african river

A multivariate measure of river quality, the Index of Biotic Integrity (IBI), was adapted to a West African river, the Konkoure (Republic of Guinea). Fish assemblages were sampled using gill-nets during the dry season to provide data for the IBI. Ten metrics were subsequently defined. The capacity of the modified IBI to assess the impact of a bauxite treatment plant was tested. The IBI decreased as expected at the impacted station. Detailed examination of the data revealed that one family, the #Mormyridae$, was almost eliminated from the impacted station, suggesting that members of this family can be considered as intolerant species in future uses of the IBI in other African rivers. (Résumé d'auteur

Patterns in species richness and endemismof European freshwater fish

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent. Methods After gathering native fish faunistic lists of 406 hydrographical networks, we defined large biogeographical regions with homogenous fish fauna, based on a hierarchical cluster analysis. Then we analysed and compared the patterns in species richness and endemism among these regions, as well as species–area relationships. Results Among the 233 native species present in the data set, the Cyprinidae family was strongly dominant (> 50% of the total number of species). Seven biogeographical regions were defined: Western Peri-Mediterranea, Central Peri-Mediterranea, Eastern Peri-Mediterranea, Ponto-Caspian Europe, Northern Europe, Central Europe and Western Europe. The highest regional species richness was observed for Central Peri-Mediterranea and Ponto-Caspian Europe. The highest endemic richness was found in Central Peri-Mediterranea. Species–area relationships were characterized by high slope values for Peri-Mediterranean Europe and low values for Central and Western Europe. Main conclusions The results were in agreement with the ‘Lago Mare’ hypothesis explaining the specificity of Peri-Mediterranean fish fauna, as well as with the history of recolonization of Central and Western Europe from Ponto-Caspian Europe following the LGM. The results also agreed with the mechanisms of speciation and extinction influencing fish diversity in hydrographical networks. We advise the use of the seven biogeographical regions for further studies, and suggest considering Peri-Mediterranean Europe and Ponto-Caspian Europe as ‘biodiversity hotspots’ for European riverine fish