Water quality assessment by means of HFNI valvometry and high-frequency data modeling

The high-frequency measurements of valve activity in bivalves (e.g., valvometry) over a long period of time and in various environmental conditions allow a very accurate study of their behaviors as well as a global analysis of possible perturbations due to the environment. Valvometry uses the bivalve's ability to close its shell when exposed to a contaminant or other abnormal environmental conditions as an alarm to indicate possible perturbations in the environment. The modeling of such high-frequency serial valvometry data is statistically challenging, and here, a nonparametric approach based on kernel estimation is proposed. This method has the advantage of summarizing complex data into a simple density profile obtained from each animal at every 24-h period to ultimately make inference about time effect and external conditions on this profile. The statistical properties of the estimator are presented. Through an application to a sample of 16 oysters living in the Bay of Arcachon (France), we demonstrate that this method can be used to first estimate the normal biological rhythms of permanently immersed oysters and second to detect perturbations of these rhythms due to changes in their environment. We anticipate that this approach could have an important contribution to the survey of aquatic systems.     

Pesticide and agro-ecological transition: assessing the environmental and human impacts of pesticides and limiting their use

Environmental Science and Pollution Research -     

Intraguild predation by <Emphasis Type="Italic">Harmonia axyridis</Emphasis> on coccinellids revealed by exogenous alkaloid sequestration

Summary.  Under laboratory conditions, the multicolored Asian lady beetle, Harmonia axyridis is well known as an intraguild predator of other ladybirds. However the real impact of this exotic species on native species was poorly investigated in the field. Because many ladybird species produce alkaloids as defensive compounds, we propose here a new method of intraguild predation monitoring in coccinellids based on alkaloid quantification by GC-MS. In laboratory experiments, adaline was unambiguously detected in fourth instar larvae of H. axyridis having ingested one egg or one first instar larva of Adalia bipunctata. Although prey alkaloids in the predator decreased with time, traces were still detected in pupae, exuviae and imagines of H. axyridis having ingested one prey when they were fourth instar larvae. Analysis of H. axyridis larvae collected in two potato fields shows for the first time in Europe the presence of exogenous alkaloids in 9 out of 28 individuals tested. This new method of intraguild predation detection could be used more widely to follow the interactions between predators and potential chemically defended insect preys.     

Biological and ecophysiological reactions of white wall rocket (Diplotaxis erucoides L.) grown on sewage sludge compost

We studied the effects of sewage sludge compost on white wall rocket (Diplotaxis erucoides L.) compared with mineral fertilization and control (without any fertilizer) in a greenhouse experiment. The plants grown on the compost-amended soil showed a different growth dynamic: a significant delay in flowering and a bigger root system. Both the compost and the fertilization treatments increased biomass and seed yield. Heavy metal (Cu, Cd, Zn, Ni) distribution within the plant was in the following order: roots > leaves > stems, except for zinc which was homogeneously distributed. The balance of mineral nutrition was not affected by treatments. Zinc was the trace element which was most taken up. Unlike many species of Brassicaceae, white wall rocket is not a hyperaccumulator. Although sewage sludge compost improved plant growth, delay in flowering shows that it is necessary to take precautions when spreading sewage sludge in natural areas.     

Screening of high production volume chemicals for estrogen receptor binding activity (II) by the MultiCASE expert system

A structurally and functionally diverse and cross-validated quantitative structure-activity knowledge database generated by the MultiCASE expert system was used to screen 2526 high production volume chemicals (HPVCs) for their estrogen receptor binding activity. 73 HPVCs were found to contain structural features or biophores that have been documented as having the ability to bind to the estrogen receptor. Potential chemicals were ranked according to their quantitatively predicted ER binding potential and the details of the biophores found in them are discussed.     

Irrigation canals as tools for climate change adaptation and fish biodiversity management in Southern France

This paper is based on the interdisciplinary research conducted in the south of France that analyses the different economic, social and environmental roles played by agricultural irrigation canals. We argue that beyond their productive role, which is to supply farmers with water, they fulfil other environmental services and play an important role in the context of future climate change to face challenges of adaptation. We point up several ecosystem services provided by such canals, e.g. replenishing the groundwater table, the development of riparian vegetation and wet areas in the Mediterranean zone, tools for regulating flooding and drought, the bases for new cultural approaches to nature. Moreover, they play an important role in the maintenance of an ichthyological biodiversity that is indispensable for the persistence of natural ecosystem. Functioning as an ecological corridor, they display interesting capacities as refuges for certain fish species under stress. Indeed, they can potentially connect upstream and downstream zones over a continuum of more than 300 km and thus covering very contrasted climatic zones (alpine versus Mediterranean). For now, most of these services remain largely unknown and underestimated. However, they serve as assets for territorial development since they combine economic, ecological and social factors whose remodelling is becoming increasingly necessary in the face of climate change.