Partitioning of Cd and Pb in the blood of European blackbirds (Turdus merula) from a smelter contaminated site and use for biomonitoring

Blood composition is commonly measured to assess exposure to and effects of metals on birds. In most of passerine species, only small volumes of blood may be sampled safely (<500 μL), which limit the measure of several markers of health status and chemical residues. Here, we documented the partitioning of Cd and Pb in the blood of European Blackbirds Turdus merula in order to propose usable relationships between whole blood concentrations (for which toxicological benchmarks exist) and those measured in the erythrocytes. Sixty-two blackbirds were trapped along a pollution gradient (smelter of Metaleurop Nord, Northern France). Blood was sampled and Cd and Pb concentrations were measured both in whole blood and in the erythrocytes only. Birds coming from the most contaminated sites exhibited high residues for both Cd and Pb. We assessed that 73% and 99% of Cd and Pb, respectively, were associated to erythrocytes. Strong linear relationships, that were not influenced by neither the age nor the sex, were established between whole blood residues and those of erythrocytes for Cd and Pb (adj-R² = 0.78 and 0.93, respectively). Present findings are promising to optimize the use of small blood samples in order to investigate several responses relative to wildlife health status.     

Impact of genetic diversity and inbreeding on the life-history of Chironomus midges over consecutive generations

We report results of a multigenerational experiment with Chironomus riparius. Two strains with a high and a low level of genetic variability were exposed to a low, environmentally relevant TBT concentration of 80 μg Sn kg⁻¹ sediment dw nominally (time weighted mean, based on measured concentrations: 4.5 μg Sn kg⁻¹ sediment dw), and various life history traits as well as genetic diversity were monitored for eleven consecutive generations. While TBT effects are hardly visible in the outbred and genetically diverse strain, the inbred and genetically impoverished strain shows a clearly reduced population growth rate compared to the control. Moreover, the impoverished strain shows an increase in fitness over time. Analyses of variation at five microsatellite loci revealed that the level of genetic variation is strongly reduced in the inbred compared to the outbred strain. Moreover, genetic diversity increases over time in the inbred strain. This finding explains the observed increase in fitness in both inbred lineages (control and TBT exposed). The results document that inbreeding and the level of genetic diversity might be of crucial importance in populations under pollution stress. Furthermore, ecotoxicological bioassays have to consider genetic diversity if results between laboratories should be comparable. Our data provides evidence that genetic diversity strongly contributes to the survival of a population exposed to chemical pollution.     

Kinetic study of γ-hexabromocyclododecane orally given to laying hens (Gallus domesticus)

Introduction  

High concentrations of hexabromocyclododecane (HBCD) sometimes recorded in free-range hens' eggs are thought to be due to soil ingestion. Of the three stereoisomers of HBCD (α-, β-, and γ-HBCD), γ-HBCD is the main component in the commercial mixture, as well as in environmental matrices, whereas the isomer profile is α-dominated in biota. In fish and in mammals, this shift is thought to be due to a rapid elimination of γ-HBCD and to its bioisomerization to the more persistent α-HBCD. The aim of the current controlled study was to better understand the fate of ingested HBCD in laying hens. The isomer profile in soil being γ-dominated, excretion kinetics of γ-HBCD into egg yolk, and accumulation in liver and in abdominal fat were investigated.     

Polycyclic aromatic hydrocarbons: bees, honey and pollen as sentinels for environmental chemical contaminants

Three beehive matrices, sampled in six different apiaries from West France, were analyzed for the presence of four polycyclic aromatic hydrocarbons (PAH4: benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene and chrysene). Samples were collected during four different periods in both 2008 and 2009. Honey samples showed the lowest levels of PAH4 contamination (min = 0.03 μg kg⁻¹; max = 5.80 μg kg⁻¹; mean = 0.82 μg kg⁻¹; Sd = 1.17). Bee samples exhibited higher levels of PAH4 contamination (min = 0.32 μg kg⁻¹; max = 73.83 μg kg⁻¹; mean = 7.03 μg kg⁻¹; Sd = 17.83) with a great dispersion of the concentrations due to four main events of high concentrations. Pollen samples showed only one major episode with the highest PAH4 concentration found (min = 0.33 μg kg⁻¹; max = 129.41 μg kg⁻¹; mean = 7.10 μg kg⁻¹; Sd = 22.28). The PAH4 concentrations found were significantly influenced by the landscape context for all beehive samples.     

A geometrical model for the effect of interference on food intake

Interference competition is often due to kleptoparasitism (food stealing). In which case, the attack distance, the distance over which one animal attacks another in an attempt to steal food, determines to a large extent the competitor density range over which interference significantly affects the intake rate of foraging animals.We develop a simple model of kleptoparasitism containing three parameters: attack distance, the density of foraging animals and a single dimensionless parameter α which summarizes the non-geometrical aspects of the interference process. Dominant and subdominant animals are not considered separately. The model predicts that the average intake rate will decrease exponentially with animal density and that a measure of the strength of interference depends on attack distance squared.The simple model is compared with a much more detailed individual-based foraging model from the literature. Simulated average intake rates are indeed well approximated by an exponential decrease with competitor density. Also the measure of interference behaves in the way expected from the simple model. By explaining the shape of the relationship between intake rate and animal density, the simple model provides insight into the behaviour of the detailed behavioural model.Insight into the role of geometry is important in the interpretation of field results and in the further development of detailed foraging models.     

Proximity to competitors changes secondary metabolites of non-indigenous cup corals, Tubastraea spp., in the southwest Atlantic

Competition for space changes species’ distributions and community organization on tropical rocky shores, and the presence of secondary metabolites in the tissues of non-indigenous species may aid them in establishing and expanding their range through negative competitive interactions. The aim of this study was to describe the range of chemical substances produced by the non-indigenous cup corals Tubastraea coccinea and T. tagusensis and to test whether they varied in the field when the corals were placed in proximity to two local competitors. Cholest-5-en-3β-ol and 9-octadecanoic acid were two common secondary metabolites found in the tissues of Tubastraea. In the competition interaction experiment, necrosis was detected on the tissues of the coral Mussismilia hispida, and this species induced variation in sterol, alkaloid, and fatty acid production in Tubastraea tissues. In contrast, a sponge overgrew Tubastraea colonies. These results indicate that chemical defense may contribute to the ability of these non-indigenous corals to invade native communities.     

Contaminant-induced irreversible changes in properties of the soil-vadose-aquifer zone: an overview

Most studies on contaminant interactions with the subsurface environment focus on contaminant transport, retention and persistence, and on potential remediation of polluted soils, vadose zones and aquifers. Changes in the soil-vadose-aquifer zone (SVAZ) matrix and properties, caused by human activities, are thus usually considered to be deviations from a normal geochemical environment, which will disappear by natural processes or by specific remediation procedures. However, contaminants may also cause, under specific conditions, irreversible changes in SVAZ properties. In this critical overview, we discuss a different aspect of contaminant-SVAZ interactions: irreversible changes in natural SVAZ properties as a result of anthropogenically-induced chemical contamination. We survey selected research results that illustrate various aspects of such phenomena, in soils, aquifers and the vadose zone. Grouping contaminants according to major and trace elements, we observe that major elements can irreversibly affect water transmission and other physical and chemical properties of the SVAZ, mainly in the liquid phase, while trace elements affect mostly the solid phase matrix.     

Runoff of pesticides from rice fields in the Ile de Camargue (Rhône river delta, France): field study and modeling

A field study on the runoff of pesticides was conducted during the cultivation period in 2004 on a hydraulically isolated rice farm of 120 ha surface with one central water outlet. Four pesticides were studied: Alphamethrin, MCPA, Oxadiazon, and Pretilachlor. Alphamethrin concentrations in runoff never exceeded 0.001 microg L(-1). The three other pesticides were found in concentrations between 5.2 and 28.2 microg L(-1) in the runoff water shortly after the application and decreased thereafter. The data for MCPA compared reasonably well with predictions by an analytical runoff model, accounting for volatilization, degradation, leaching to groundwater, and sorption to soil. The runoff model estimated that runoff accounted for as much as 18-42% of mass loss for MCPA. Less runoff is observed and predicted for Oxadiazon and Pretilachlor. It was concluded that runoff from rice paddies carries important loads of dissolved pesticides to the wetlands in the Ile de Camargue, and that the model can be used to predict this runoff.