A chacun ses sciences participatives: les conditions d'un observatoire participatif de la biodiversité sur le Bassin d'Arcachon

This paper considers the social and scientific requirements for a citizen science monitoring programme on biodiversity in Arcachon Bay (France). The sociological study reveals tensions between different conceptions of what a citizen science programme should be: a means for storing oriented-data; a new way to co-create scientific knowledge; a political communication tool; a way to develop citizen stewardship; or a place for expressing activist environmental demands. Citizen science programmes also tend to reveal tensions between participatory governance and classical management of environmental issues. Despite a seeming consensus amongst actors on biodiversity conservation, in practice contests over different citizen science conceptions have the potential to re-define environmental issues, to re-specify relationships between science and society and outline new management priorities

Populations zooplanctioniques dans le Bassin de Marennes-Oleron; dynamique de population, nutrition et production des Copepodes dominants

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Effects of a brief climatic event on zooplankton community structure and distribution in Arcachon Bay (France)

Short-term changes in zooplankton community structure and distribution in relation to changes in hydrological features were studied during summer in two distinct areas of Arcachon Bay (France) from July to September 1986. One sampling site was chosen in the northern part of the bay, influenced by oceanic inputs, and the other one in the south-eastern part of the bay, close to an estuarine zone, influenced by the river Leyre's inputs. Three different zooplankton assemblages were identified according to a temperature-salinity gradient: (i) an estuarine assemblage dominated by Acartia bifilosa and Acartia tonsa, (ii) an autochthonous assemblage composed of Acartia discaudata, and (iii) a coastal neritic one composed of Paracalanus parvus, Oncaea venusta and Penilia avirostris. All these latter assemblages remained stable during most part of the study period. However, a brief climatic event (storm event) occurred in mid-August and gave rise to a sharp decrease in temperatures along with significant changes in zooplankton structure and distributions in the bay. The estuarine community vanished and was replaced by the autochthonous community. In the northern part of the bay, the coastal neritic community succeeded the previously observed autochthonous community

The paradox between the long-term decrease of egg mass size of the calanoid copepod Eurytemora affinis and its long-term constant abundance in a highly turbid estuary (Gironde estuary, France)

Eurytemora affinis egg mass size-a commonly used demographic parameter-was surveyed in the Gironde estuary. Its decrease between 1978 and 2003 contrasted with the stability of population density during this long-term period. Different hypotheses were tested to explain this paradox. (i) Upstream shift of the population: Even though the population of E. affinis shifted upstream due to a greater penetration of marine water, no relationship between the population shift and demographic parameters was observed: the egg mass size exhibited the same evolution upstream. (ii) Water warming: No early egg production and no change of female size that could metabolically limit the egg mass size was observed. (iii) Food limitation: The change in food quality observed did not result in any change in total copepod abundance. (iv) Faster renewal of egg masses: The paradox cannot be explained by this factor and the number of adults observed nowadays is higher than the number of eggs produced by females, whereas fecundity rates strongly increased. The paradox is probably explained by the expulsion of viable subitaneous eggs. This may represent a recent behaviour adaptation of the copepod to environmental changes

To each participatory sciences. Conditions for a participatory biodiversity

This paper considers the social and scientific requirements for a citizen science monitoring programme on biodiversity in Arcachon Bay (France). The sociological study reveals tensions between different conceptions of what a citizen science programme should be: a means for storing oriented-data; a new way to co-create scientific knowledge; a political communication tool; a way to develop citizen stewardship; or a place for expressing activist environmental demands. Citizen science programmes also tend to reveal tensions between participatory governance and classical management of environmental issues. Despite a seeming consensus amongst actors on biodiversity conservation, in practice contests over different citizen science conceptions have the potential to re-define environmental issues, to re-specify relationships between science and society and outline new management priorities

LONG-TERM ENVIRONMENTAL CHANGES IN THE GIRONDE ESTUARY

participantThe Gironde estuary is considered the largest South-Western European estuary and covers an area of 625 km2 at high tide. This transition zone between marine and freshwater environments is formed by the junction of the Garonne and the Dordogne rivers. The Gironde is characterized by a strong spatiotemporal variability of environmental parameters, modulating biological response. While most studies deal with the impact of anthropogenic pressures on estuaries, this research aims at understanding and distinguishing the part of variability that can be explained by human local activities from those that is linked to Climate Change. Using data from the ecological monitoring of the Blayais nuclear power plant, this research contributes to better know the estuarine evolution over the last thirty years. This paper presents the chemical, physical and climatic parameters changes by characterizing global and local trends, interannual variability and an eventual periodicity using different data analyses (i.e. linear regression, moving average, and eigenvectors filtering). Then, correlations between environmental parameters were analyzed and the potential influence of climate variability was evaluated with a standardized Principal Component Analysis

Evaluation of coastal perturbations: A new mathematical procedure to detect changes in the reference state of coastal systems

International audiencehe pressure exerted by human activities on living systems has become so intense that it is inspiring the inception of a global network of monitoring of the biosphere and the use of robust statistical procedures to detect potential changes. Here, we propose a new multivariate non-parametric procedure, based on the Mahalanobis generalised distance and a simplification of the multiple response permutation procedure to identify rapidly changes in any natural systems. The procedure can be virtually coupled on all monitoring programmes and is not influenced by missing data, a common feature found in many ecological databases. In France, physical, chemical and biological variability of coastal waters have been monitored since 1997 by the SOMLIT Network. Applied to this data set, this technique enabled a first quantification of the impacts of human disturbance through changes in the concentration of nutrients. Our results revealed how climate may interact with anthropogenic pressure to alter coastal marine systems and suggest a synergism between nutrient enrichment, human activities and local climatic conditions. Indeed some effects of climate (e.g. insolation duration - increase in duration of daylight) may attenuate the fertility of coastal systems, while some others (e.g. precipitation) amplify the human signals

Local changes in copepod composition and diversity in two coastal systems of Western Europe

International audienceWhile long-term monitoring is essential to improve our knowledge of marine ecosystems health, it remains challenging to summarise complex ecological data in order to characterise and understand biodiversity trends. To compile monitoring data across large numbers of species, scientists and policymakers mainly rely on diversity and species richness indices. This task may prove complicated however, as many indices exist and no individual metric undoubtedly emerges as the best overall. Here, using data from zooplankton surveys from 1998 to 2014, we examined year-to-year changes in copepod communities in two littoral ecosystems of Western Europe - the Arcachon Bay and the Gironde estuary - that share similar climate, but with different local ecological processes, especially hydrological conditions. We tested the ability of commonly used α and β-diversity metrics, such as species richness, Pielou's evenness or Jaccard's index, to mirror year-to-year changes in species abundances and we detected a synchronous change in both copepod abundances and α-diversity that took place circa 2005 in the two sites. In response to changes in environmental conditions such as nutrients, salinity, river discharge or particulate matter, two opposite biodiversity trends were observed, with a decrease in copepod diversity in the Arcachon Bay but an increase in the downstream part of the Gironde estuary. Although diversity metrics allowed us to well detect trends, the use of multivariate approaches such as principal component analysis provided important information on how and why diversity fluctuates. Our study provides evidence that long-term monitoring programmes must be encouraged for optimising management and conservation actions such as the Marine Strategy Framework Directive and that more local comparative studies need to be initiated for better characterising diversity trajectories at very fine scales at which ecologists often work

Phytoplankton spring bloom of the Gironde plume waters in the Bay of Biscay: early phosphorus limitation and food-web consequences

During the spring 1995 (2-25 May), a cruise was carried on the RV Poseidon (Germany) on the continental shelf of the south Bay of Biscay. The objective was a comprehensive study of the planktonic food web within the Gironde plume waters. In these waters phosphate was present at very low concentrations (undetectable to < 0.1 mu mol.L(-1)), whereas nitrate, silicate and ammonium concentrations were much higher (several mu mol.L(-1) for nitrate and silicate and 0.5 to 1.0 mu mol.L(-1) for ammonium). The size distribution of the phytoplankton biomass (estimated from chlorophyll a measurements by high performance liquid chromatography) and primary production (measured by (14)C in situ method) showed a great proportion of small (40 to 70 % < 3 mu m) and active autotrophic cells (growth rates estimated from 0.4 to 0.8 d(-1) for the entire euphotic layer). Considering the very high values of NO(3)-N:PO(4)-P ratios and the high C:P and N:P ratios for the particulate organic matter, it is suggested that an early phosphorus depletion limits the spring bloom phytoplankton and particularly the new production (nitrate uptake coming from the Gironde waters). From these results and other simultaneous observations on the heterotrophic processes (such as grazing of microzooplankton), we can conclude that the planktonic food web would be close to a maintenance system as defined by Platt et al. The possible generalisation of these results for each spring is discussed with respect to the scarcity of previous and reliable phosphate data