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Patrick Berrebi Pascal Rodriguez Jean-Antoine Tomasini Ghislaine Cattaneo-Berrebi Alain J. Crivelli 《Estuarine, Coastal and Shelf Science》2005,65(4):708-716
The presence and the distribution of two cryptic sedentary gobies, Pomatoschistus microps and Pomatoschistus marmoratus, were investigated in several lagoons stretching along the Golfe du Lion, southern France Mediterranean coast, and Corsica. Pomatoschistus microps is the only sedentary Pomatoschistus species in two shallow lagoons with large variations of salinity and temperature. In contrast, P. marmoratus, another sedentary species, can be found preferentially in a deep salty lagoon with small salinity variations. Both species occur sympatrically in the Rhone Delta and hybridise, producing fertile offspring. Using allozymes, competition, linked to fitness, is invoked to explain the distribution pattern of these sibling species. 相似文献
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ML Camara B Mérigot F Leprieur JA Tomasini I Diallo M Diallo 《African Journal of Marine Science》2016,38(2):189-206
In a context of growing fishing pressures and recommendations for an ecosystem approach to fisheries, there is a need to monitor changes in fish communities over time. In this study, we analysed data from scientific trawl surveys carried out on the continental shelf off Guinea between 1985 and 2012. We performed factorial analyses and calculated biodiversity indices to characterise the changes in the structure and composition of fish communities that occurred over the 28-year period in this area, particularly given intensive fishing activities. We show that, over the study period, fish communities on the Guinean shelf were structured primarily according to spatial factors, with temporal changes being less pronounced than expected. However, a temporal analysis of biodiversity indices and species dominance showed that the intensification of fishing had significant effects on the general ecological features of the fish assemblages under study. There was a decrease in fish density and in mean trophic level. In addition, there were changes in species dominance, whereby large, slow-growing species with high commercial value were gradually replaced by smaller, fast-growing species of lesser commercial interest. These results from field observations are in line with some conclusions from previous modelling studies in the same geographical area, and provide further support for the hypothesis of a progressive ‘ecosystem effect of fishing’ occurring in Guinean waters. 相似文献
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David Mouillot Olivier Dumay Jean Antoine Tomasini 《Estuarine, Coastal and Shelf Science》2007,71(3-4):443-456
The fundamental idea behind the study of biodiversity patterns is the presumed connection between the shape of species assemblages and the functional ways in which they are organized, this functional organization referring to how species are related to one another, as competitors or members of a web of interactions and to how species are facing similar environmental constraints. Amongst the different facets of biodiversity, functional diversity is certainly a key for ecosystem processes in coastal areas. However, surprisingly, patterns of functional diversity have received little attention until now. After presenting a common framework linking functional diversity patterns to species coexistence theories, the aim of our study was twofold: (1) to seek assembly rules in brackish lagoon fish communities drove by functional traits. To this aim we used null models to examine the influence of two opposing forces acting on community structure: interspecific competition that might prevent the coexistence of the most similar species, and environmental filters that might result in the most similar species to coexist. (2) To seek relationships between fish functional diversity and environmental gradients, if any. Fish sampling was carried out in two coastal lagoons where stations differ considerably in terms of physicochemical parameters. Using morphological functional traits, functional diversity of fish communities was estimated using two recently published indices as well as a new proposed index. Firstly our study was not able to demonstrate a limitation of similarity in coexisting lagoon fishes due to interspecific competition. Conversely our results support the niche filtering hypothesis preventing species too dissimilar from one another to co-occur at the same station. Secondly, salinity was positively related to the functional diversity of fishes in both lagoons suggesting that within species assemblages near the channel species are less redundant than at stations far from the channel where species tend to be functionally similar (benthic and eating zooplankton). 相似文献
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David Mouillot Jean-Michel Culioli Alain Lepretre Jean-Antoine Tomasini 《Marine Ecology》1999,20(1):19-34
For the correct management of the future International Marine Park of Bonifacio, a sampling strategy must be adopted to follow the population fluctuations of certain species of fish. This sampling will be carried out by SCUBA visual census using the fixed point method. The information to be gleaned using this method will include estimates of biomass. These data will subsequently be used to perform both spatial comparisons between sites and temporal comparisons over periods of several years. In order to reveal the existence of statistically significant differences, the sampling strategy adopted must allow accurate means to be obtained which possess relatively low coefficients of variability. The calculation of this optimum sampling depends on the spatial distribution of the species examined. The Taylor law (s2 = a ×x b), which represents a much utilized mean-variance relationship, will be used to compare the aggregation of three species of fish (Symphodus ocellatus,Serranus scriba and Diplodus annularis) on two different substrate types (Posidonia oceanica meadows and rocks) and for four sites in the Lavezzi Islands. The goodness of fit of this law to the biomass data will allow an optimum sampling strategy to be determined for each species with coefficients of variability of 10 and 25%. 相似文献
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