Les gravières de la plaine alluviale de la Garonne comme milieu d'accueil de la Foulque macroule (Fulica atra)

Dans la région Midi-Pyrénées, la création de plus en plus importante de gravières a permis l'installation et la nidification de plusieurs espèces d'oiseaux d'eau dont la Foulque macroule (Fulica atra) est la plus abondante. Une étude des populations de cette espèce a été réalisée pendant deux ans sur deux sites distincts de la plaine alluviale de la Garonne. L'analyse de la distribution des oiseaux en fonction des paramètres du milieu et au cours du temps a permis de mettre en évidence les facteurs qui régissent le stationnement des foulques. Les macrophytes sont une ressource trophique essentielle, lorsque celles-ci disparaissent en fin d'hivernage les pelouses deviennent de manière transitoire des zones de gagnage importantes. En période de reproduction la surface trop faible d'habitat favorable de type roseaux ou massette limite considérablement le nombre de couples nicheurs. Le dérangement est également préjudiciable pendant cette période et en migration postnuptiale. Dans des plans d'aménagement et de gestion des zones humides, la prise en compte de ces informations permettra une meilleure colonisation de ces milieux par les oiseaux.In the Midi-Pyrénées, the increasing abundance of gravel pits bas allowed several species of waterbirds to colonize the region and breed, the most abundant of these being the Coot (Fulica atra). Populations of this species were studied for two years at two sites in the Garonne floodplain. The analysis of habitat characteristics highlights the factors which control the temporal and spatial distribution of Coots. Macrophyies are an essential food resource and when they disappear at the end of the winter, areas of short-grass become temporarily important as foraging grounds. During the breeding season there is a lack of suitable habitat such as reed-beds which limits the number of coots nesting. Coots are also disturbed during breeding and on migration and these factors should be taken into account in any management plan of these wetlands for waterbirds

Ecology, behaviour and management of the European catfish

The extreme body sizes of ‘megafishes’ associated with their high commercial values and recreational interests have made them highly threatened in their native range worldwide by human-induced impacts such as overexploitation. Meanwhile, and because of the aforementioned interests, some megafishes have been introduced outside of their native range. A notable exampled is the European catfish (Silurus glanis), one of the few siluriforms native from western Europe and among the 10 largest freshwater fish worldwide, attaining a total length over 2.7 m and a documented mass of 130 kg. Its distinct phylogeny and extreme size imply many features rare among other European fish such as peculiar behaviours (massive aggregations, beaching), consumption of large bodied prey, fast growth rate, long lifespan, high fecundity, nest guarding and large eggs. The spread of the species is likely to continue due to illegal introduction coupled with natural range extension due to current and future climate change. Based on these attributes and potential future risks, this introduced giant predator in European fresh waters could provide a novel model species of high utility for testing aspects of ecological and invasion theory and associated hypotheses. Here, we reviewed the most recent knowledge on the current distribution and the ecology of the species to understand how this can help advance our understanding of biological invasions. We also identified key research questions that should help stimulating new research on this intriguing, yet largely unknown, species and, more generally, on the ecology of invasive species

Gravel pits support waterbird diversity in an urban landscape

We assessed the benefit of 11 gravel pits for the settlement of waterbird communities in an urbanized area lacking natural wetlands. Gravel pits captured 57% of the regional species pool of aquatic birds. We identified 39 species, among which five were regionally rare. We used the Self Organizing Map algorithm to calculate the probabilities of presence of species, and to bring out habitat conditions that predict assemblage patterns. The age of the pits did not correlate with assemblage composition and species richness. There was a positive influence of macrophyte cover on waterbird species richness. Larger pits did not support more species, but species richness increased with connectivity. As alternative wetland habitats, gravel pits are attractive to waterbirds, when they act as stepping stones that ensure connectivity between larger natural and/or artificial wetlands separated in space

Assessing the conservation value of waterbodies: the example of the Loire floodplain (France)

In recent decades, two of the main management tools used to stem biodiversity erosion have been biodiversity monitoring and the conservation of natural areas. However, socio-economic pressure means that it is not usually possible to preserve the entire landscape, and so the rational prioritisation of sites has become a crucial issue. In this context, and because floodplains are one of the most threatened ecosystems, we propose a statistical strategy for evaluating conservation value, and used it to prioritise 46 waterbodies in the Loire floodplain (France). We began by determining a synthetic conservation index of fish communities (Q) for each waterbody. This synthetic index includes a conservation status index, an origin index, a rarity index and a richness index. We divided the waterbodies into 6 clusters with distinct structures of the basic indices. One of these clusters, with high Q median value, indicated that 4 waterbodies are important for fish biodiversity conservation. Conversely, two clusters with low Q median values included 11 waterbodies where restoration is called for. The results picked out high connectivity levels and low abundance of aquatic vegetation as the two main environmental characteristics of waterbodies with high conservation value. In addition, assessing the biodiversity and conservation value of territories using our multi-index approach plus an a posteriori hierarchical classification methodology reveals two major interests: (i) a possible geographical extension and (ii) a multi-taxa adaptation

Biological traits of European pond macroinvertebrates

Whilst biological traits of river macroinvertebrates show unimodal responses to geographic changes in habitat conditions in Europe, we still do not know whether spatial turnover of species result in distinct combinations of biological traits for pond macroinvertebrates. Here, we used data on the occurrence of 204 macroinvertebrate taxa in 120 ponds from four biogeographic regions of Europe, to compare their biological traits. The Mediterranean, Atlantic, Alpine, and Continental regions have specific climate, vegetation and geology. Only two taxa were exclusively found in the Alpine and Continental regions, while 28 and 34 taxa were exclusively recorded in the Atlantic and Mediterranean regions, respectively. Invertebrates in the Mediterranean region allocated much energy to reproduction and resistance forms. Most Mediterranean invertebrate species had narrow thermal ranges. In Continental areas, invertebrates allocated lesser energy to reproduction and dispersal, and organisms were short lived with high diversity of feeding groups. These characteristics suggest higher resilience. The main difference between ponds in the Alpine and Atlantic regions was their elevation. Alpine conditions necessitate specific adaptations related to rapid temperature fluctuations, and low nutrient concentrations. Even if our samples did not cover the full range of pond conditions across Europe, our analyses suggest that changes in community composition have important impacts on pond ecosystem functions. Consistent information on a larger set of ponds across Europe would be much needed, but their low accessibility (unpublished data and/or not disclosed by authors) remains problematic. There is still, therefore, a pressing need for the incorporation of high quality data sets into a standardized database so that they can be further analyzed in an integrated European-wide manner

Do native brown trout and non-native brook trout interact reproductively?

Reproductive interactions between native and non-native species of fish have received little attention compared to other types of interactions such as predation or competition for food and habitat. We studied the reproductive interactions between non-native brook trout (Salvelinus fontinalis) and native brown trout (Salmo trutta) in a Pyrenees Mountain stream (SW France). We found evidence of significant interspecific interactions owing to consistent spatial and temporal overlap in redd localizations and spawning periods. We observed mixed spawning groups composed of the two species, interspecific subordinate males, and presence of natural hybrids (tiger trout). These reproductive interactions could be detrimental to the reproduction success of both species. Our study shows that non-native species might have detrimental effects on native species via subtle hybridization behavior

Capacité d'accueil des gravières de la plaine alluviale de la Garonne vis-à-vis du Grèbe huppé (

Les activités humaines, à l'origine de la disparition de nombreuses zones humides naturelles, permettent la création de milieux aquatiques artificiels comme les lacs de barrage, les rizières ou les gravières. Dans la région Midi-Pyrénées, la création de plus en plus importante de gravières a permis l'installation et la nidification de plusieurs espèces d'oiseaux d'eau dont le Grèbe huppé (Podiceps cristatus L.). Cependant, après une phase de colonisation rapide, les effectifs stagnent à un niveau assez faible. Une étude des populations de Grèbe huppé a été réalisée pendant deux ans sur deux sites distincts de la plaine alluviale de la Garonne. L'analyse de la distribution des oiseaux en fonction des paramètres du milieu et au cours du temps a permis de mettre en évidence les facteurs qui régissent le stationnement des grèbes. En période de nidification, la présence d'îles et de végétation aquatique et riveraine sont des éléments très favorables. Les zones de pleine eau, en milieu suffisamment ouvert, sont aussi des lieux d'accueil favorables, notamment en période de mue. Un dérangement humain trop important est toujours préjudiciable. Dans des plans d'aménagement et de gestion des zones humides, la prise en compte de ces informations permettra une meilleure colonisation de ces milieux par les oiseaux

Les gravières de la plaine alluviale de la Garonne comme milieu d’accueil de la Foulque macroule (Fulica atra)

In the Midi-Pyrénées, the increasing abundance of gravel pits has allowed several species of waterbirds to colonize the region and breed, the most abundant of these being the Coot (Fulica atra). Populations of this species were studied for two years at two sites in the Garonne floodplain. The analysis of habitat characteristics highlights the factors which control the temporal and spatial distribution of Coots. Macrophytes are an essential food resource and when they disappear at the end of the winter, areas of short-grass become temporarily important as foraging grounds. During the breeding season there is a lack of suitable habitat such as reed-beds which limits the number of coots nesting. Coots are also disturbed during breeding and on migration and these factors should be taken into account in any management plan of these wetlands for waterbirds.Dans la région Midi-Pyrénées, la création de plus en plus importante de gravières a permis l’installation et la nidification de plusieurs espèces d’oiseaux d’eau dont la Foulque macroule (Fulica atra) est la plus abondante. Une étude des populations de cette espèce a été réalisée pendant deux ans sur deux sites distincts de la plaine alluviale de la Garonne. L’analyse de la distribution des oiseaux en fonction des paramètres du milieu et au cours du temps a permis de mettre en évidence les facteurs qui régissent le stationnement des foulques. Les macrophytes sont une ressource trophique essentielle, lorsque celles-ci disparaissent en fin d’hivernage les pelouses deviennent de manière transitoire des zones de gagnage importantes. En période de reproduction la surface trop faible d’habitat favorable de type roseaux ou massette limite considérablement le nombre de couples nicheurs. Le dérangement est également préjudiciable pendant cette période et en migration postnuptiale. Dans des plans d’aménagement et de gestion des zones humides, la prise en compte de ces informations permettra une meilleure colonisation de ces milieux par les oiseaux.Santoul F., Tourenq J.-N. Les gravières de la plaine alluviale de la Garonne comme milieu d’accueil de la Foulque macroule (Fulica atra). In: Revue d'Écologie (La Terre et La Vie), tome 57, n°2, 2002. pp. 165-180

Spatial patterns of the biological traits of freshwater fish communities in south-west France

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