Is scuba sampling a relevant method to study microhabitat in lakes? Examples and comparisons for three European species

We compared fish microhabitat use patterns in the littoral zone of a lake using a new direct method (i.e. Point Abundance Sampling by Scuba, PASS) and the widely used Point Abundance Sampling by Electrofishing technique (PASE). We collected microhabitat data for age 0+ roach (Rutilus rutilus L.), perch (Perca fluviatilis L.), and pike (Esox lucius L.). The two methods yelded different results for fish assemblage structure and microhabitat patterns. Using PASE, fish were mainly found in "shelter habitats" such as shallow waters and dense vegetation. It is likely that this behaviour is caused by the disturbance of the observer stamping around. Using PASS, fish escapement behaviour was rarely observed. Therefore, we concluded that this direct and non-destructive sampling technique is able to provide an accurate microhabitat estimation of a fish community and is assumed to be more suitable than PASE for fish habitat studies

Role of fish communities in particulate organic matter fluxes between salt marshes and coastal marine waters in the Mont Saint-Michel bay.

Among the 90 fishspecies censused in the Mont Saint-Michel Bay (France), 23 colonise and forage in the salt marshes during flood. Therefore, this environmentmay play an important trophic and nursery role for these species. This community is largely dominated by mullets (81% of the biomass), Liza ramada and secondarily L. aurata. But gobies (mainly Pomatoschistus minutus and P. lozanoï) and sea bass (Dicentrarchus labrax) are also present; they represent respectively 11% and 4% of the biomass. During the tide cycles, mullets export from salt marshes about 7% of their body weight (FW) containing a mixture of sediment (43%), organic matter (24%) and water (33%). Gobies and sea bass mainly feed on dwelling macro-invertebrates, and they export respectively 4.5% and 10% of their body weight during a tide cycle. Thus, we estimated that 50 tonnes year−1 of particulate organic matter (dry weight POM) are exported from the 4000 ha of salt marshes to the marine coastal waters. These fish communities appear to be POM transporters and could play a significant role in the global energy budgets of coastal environments such as Mont Saint-Michel Bay. According to the seasons and the years, the energy exported by fish communities is assumed to range between 0 and 10% of the total POM output

Fish Invasions in the World's River Systems: When Natural Processes Are Blurred by Human Activities

Because species invasions are a principal driver of the human-induced biodiversity crisis, the identification of the major determinants of global invasions is a prerequisite for adopting sound conservation policies. Three major hypotheses, which are not necessarily mutually exclusive, have been proposed to explain the establishment of non-native species: the “human activity” hypothesis, which argues that human activities facilitate the establishment of non-native species by disturbing natural landscapes and by increasing propagule pressure; the “biotic resistance” hypothesis, predicting that species-rich communities will readily impede the establishment of non-native species; and the “biotic acceptance” hypothesis, predicting that environmentally suitable habitats for native species are also suitable for non-native species. We tested these hypotheses and report here a global map of fish invasions (i.e., the number of non-native fish species established per river basin) using an original worldwide dataset of freshwater fish occurrences, environmental variables, and human activity indicators for 1,055 river basins covering more than 80% of Earth's surface. First, we identified six major invasion hotspots where non-native species represent more than a quarter of the total number of species. According to the World Conservation Union, these areas are also characterised by the highest proportion of threatened fish species. Second, we show that the human activity indicators account for most of the global variation in non-native species richness, which is highly consistent with the “human activity” hypothesis. In contrast, our results do not provide support for either the “biotic acceptance” or the “biotic resistance” hypothesis. We show that the biogeography of fish invasions matches the geography of human impact at the global scale, which means that natural processes are blurred by human activities in driving fish invasions in the world's river systems. In view of our findings, we fear massive invasions in developing countries with a growing economy as already experienced in developed countries. Anticipating such potential biodiversity threats should therefore be a priority

Analyse des teneurs en nitrates d'une parcelle agricole en culture maraichere

* INRA, Centre de Recherche d'Avignon, Unite Regionale de Documentation, Montfavet (FRA) Diffusion du document : INRA, Centre de Recherche d'Avignon, Unite Regionale de Documentation, Montfavet (FRA

Prédiction du potentiel d'invasion des espèces non natives par des modèles de niche (approches méthodologiques et applications aux poissons d'eau douce sur le territoire français)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Fishes of the Mitaraka Mountains (French Guiana)

Sébastien Brosse, Fréderic Melki, Régis Vigouroux (2019): Fishes of the Mitaraka Mountains (French Guiana). Zoosystema 41 (8): 131-151, DOI: 10.5252/zoosystema2019v41a

FIG. 22 in Fishes of the Mitaraka Mountains (French Guiana)

FIG. 22. — Laimosemion geayi (Vaillant, 1889). Photograph: F. Melki.Published as part of <i>Sébastien Brosse, Fréderic Melki & Régis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8)</i> on page 149, DOI: 10.5252/zoosystema2019v41a8, <a href="http://zenodo.org/record/2639414">http://zenodo.org/record/2639414</a&gt

Data publication: Contemporary environment and historical legacy explain functional diversity of freshwater fishes in the world rivers

Script and data used for the analysis and figures plotting in paper "Contemporary environment and historical legacy explain functional diversity of freshwater fishes in the world rivers

FIG. 23 in Fishes of the Mitaraka Mountains (French Guiana)

FIG. 23. — Crenicichla albopunctata Pellegrin, 1904. Photograph: F. Melki