Contribution to the ecotoxicological study of cadmium,lead, copper and zinc in the mussel Mytilus edulis

The understanding of natural fluctuations of metal concentrations in mussels used as bio-indicators is indispensable for a good assessment of the disturbances due to pollution. We have studied thoroughly the factors which condition bioaccumulation by using controlled populations of mussels, Mytilus edulis L., sampled monthly over more than two years (March 1982–May 1984) in the Bay of Bourgneuf, France. Seasonal changes in metal levels have been recognized, maximum values being observed in winter and early spring and minimum in later spring and summer. Depending on metal and size group, the ratios between these maximum and minimum values varied between 1.56 and 3.43. The fluctuations in soft-tissue weight appear to be the main explanatory factor of seasonal variations in metal concentrations in mussels. Fluctuations in metal levels related to size of mussels were observed. Except for cadmium in mussels with a mean dry weight of soft tissues >0.2 g, a slight decrease in metal concentrations was observed for growing individuals: the regression coefficient b was -0.10, -0.11, -0.13 and -0.27 for Cd, Cu, Zn and Pb, respectively. The metals examined were rather uniformly distributed among the different groups of organs (visceral mass, gills and palps, remainder) and, consequently, several analyses of metals in different organs do not provide much more information than one analysis on the whole soft tissues. It is concluded that fluctuations related to size or season are reflected by only moderate differences in the maximum and minimum concentrations of metals in the mussels, but that they are nevertheless sufficient to conceal low chronic or short-term pollution, except at those sites where the normal environmental conditions are well-documented.     

Sustainable livelihoods and people’s vulnerability in the face of coastal hazards

The present study investigates into the link between people’s vulnerability in the face of coastal hazards and sustainable livelihoods. It focuses on the town of Borongan in the Philippines and draws on questionnaire-based surveys and focus group discussions. This research shows that local fishermen are often compelled to go out fishing despite pending typhoon or storm surge to sustain the daily needs of their family. Its also demonstrates that the capacity of these people to protect themselves from the threat is constrained by poor and fragile livelihoods. In the event of a crisis, the study argues that people resort to a range of adjustments on their daily life which is rooted in the strength and diversity of their livelihoods. To reduce people’s vulnerability and enhance capacities to face coastal hazards, the study fosters Community-Based Disaster Risk Reduction with special emphasis to sustainable livelihoods.     

Patterns of bioaccumulation of an essential trace element (zinc) and a pollutant metal (cadmium) in larvae of the prawn Palaemon serratus

Palaemon serratus Pennant larvae from females caught near Roscoff (France) or the Bay of Biscay in 1983, were reared in the laboratory. From hatching to the first stage after metamorphosis, the larvae were exposed to zinc and cadmium introduced separately or together into the rearing medium. At the end of experimental contamination, the concentrations of the two metals in the organisms were determined. The level of zinc in organisms was mainly independent of its concentration in the water, suggesting that the bioaccumulation of this essential trace element is controlled by some physiological process. The accumulation of cadmium in the larvae paralleled the overloads of this metal in the water. Increased zinc concentrations in water have little or no effect on the cadmium levels in organisms. The most important interaction between these two metals is an antagonism exerted by cadmium on the biological uptake of zinc.     

Behavioural and biochemical responses of two marine invertebrates Scrobicularia plana and Hediste diversicolor to copper oxide nanoparticles

Engineered nano-sized Cu oxide particles are extensively used in diverse applications. Because aquatic environments are the ultimate “sink” for all contaminants, it is expected that nanoparticles (NP) will follow the same fate. In this study, two marine invertebrates Scrobicularia plana and Hediste diversicolor were chosen as ecotoxicological models. The aim was to evaluate behavioural (burrowing kinetics, feeding rate) and biochemical (biomarkers) responses of S. plana and H. diversicolor exposed in the laboratory to Cu (10 μg L⁻¹) added in natural seawater either in the form of engineered nanoparticles (NPs) of CuO or as dissolved Cu in 2% HNO₃. Exposure was characterized by considering (i) the physico-chemical fate of NP (ii) the fraction of labile Cu in experimental media and (iii) Cu bioaccumulation. Results showed high aggregation of CuO NPs in seawater and no additional bioavailable Cu concentrations. Behavioural impairments were observed in S. plana exposed to CuO NPs or soluble Cu whereas in H. diversicolor, only the exposure to soluble Cu led to a burrowing decrease. No obvious neurotoxicity effects were revealed since in both species, no changes in cholinesterasic activity occurred in response to both forms of Cu exposure. Biomarkers of oxidative-stress catalase and glutathione-S-transferase were enhanced in both species whereas superoxide dismutase was increased only in S. plana exposed to CuO NPs. Metallothionein-like protein was increased in bivalves exposed to both forms of Cu. Since, no detectable release of soluble Cu from CuO NPs occurred during the time of experiment, ecotoxicity effects seem to be related to CuO NPs themselves.     

Potential influence of confounding factors (size,salinity) on biomarkers in the sentinel species <Emphasis Type="Italic">Scrobicularia plana</Emphasis> used in programmes monitoring estuarine quality

Introduction  

To use biomarkers in monitoring programmes, potential confounding factors must be considered. In the clam Scrobicularia plana, the influence of size and salinity on biomarkers at different levels of biological organisation has been examined.     

Trace-metal detoxification and tolerance of the estuarine worm<Emphasis Type="Italic"> Hediste diversicolor</Emphasis> chronically exposed in their environment

Polychaete worms (Hediste diversicolor) originating from a strongly metal-contaminated area (Restronguet Creek) and a relatively clean site (Blackwater estuary) were exposed to a range of experimental doses of Ag, Cd, Cu and Zn. Specimens from both populations were compared to assess their relative sensitivity to metal stress and the physiological mechanisms involved in their respective adaptive strategies for coping with increased metal exposures. Taking into account the LC₅₀ values, increased tolerance to Cd, Cu and Zn of the Restronguet Creek worms over that of the Blackwater was demonstrated, whereas the opposite was shown for Ag. An abundant secretion of mucus in response to toxicants was observed, possibly reducing metal availability for uptake, at least under laboratory conditions. This mechanism was particularly active in specimens from Restronguet Creek exposed to Ag and Cu. Unexpectedly, of the two worm populations, Blackwater worms contained significantly higher concentrations of cytosolic heat-stable compounds (CHSTC), a category of cytosolic components that includes metallothioneins, the detoxificatory role of which is well documented, and other compounds binding trace metals via sulphur bonds. However, the concentration of such compounds is not totally representative in itself of their involvement in metal detoxification, because a high rate of their turnover in metal-exposed worms might be responsible for (at least) the Cu storage associated with S in lysosomes as a consequence of the breakdown of Cu-thionein. Cu-containing lysosomes were abundant in epidermal cells of Restronguet Creek worms, but were lacking in Blackwater worms. Extracellular granules present in the epicuticle also contained S and Cu, their number and size being much more important in Restronguet Creek worms, and they appear to be a major detoxificatory store for accumulated Cu. Spherocrystals in cells of the gut wall seem to be the major detoxified store of Zn in Restronguet Creek worms, whereas in specimens from the Blackwater they were also present but contained only S and Ca at detectable levels. Evidence was also found for the presence of detoxificatory intracellular structures containing other metals and metalloids in the tegument and gut epithelium of Restronguet Creek worms.Communicated by S.A. Poulet, Roscoff     

Academic publishing in disaster risk reduction: past,present, and future

Nowadays there are approximately 80 Anglophone journals that deal primarily with disaster risk reduction (DRR) and allied fields. This large array signals a sustained, if uneven, growth in DRR scholarship but also competition between the offerings of different publishers and institutions. The purpose of this article is first to summarise the development of academic publishing on DRR from its early beginnings to the present day. The paper then evaluates the current state of publishing in this field and discusses possible future trends. Next, it identifies some possible opportunities, challenges, expectations, and commitments for journal editors both within DRR and academia more broadly, including those that refer to changes in the use of terminology, the relentless increase in the number of papers submitted, the expansion and dangers of predatory journals, different peer review models, open access versus paywalls, citations and bibliography metrics, academic social networks, and copyright and distribution issues.     

Contribution to the ecotoxicological study of cadmium,copper and zinc in the mussel Mytilus edulis

A regulation of internal levels of some essential metals has been observed in various animals, whereas the bioaccumulation of several non-essential metals parallels their overloads in water. In the mussel Mytilus edulis L., we have attempted to determine if such a phenomenon exists by comparing the patterns of accumulation of copper and zinc vs cadmium. With this aim, mussels collected in the Bay of Bourgneuf (France) in November 1983 were exposed to these metals for 16 d. At external levels of zinc as high as 100 gl^-1, mussels were able to maintain a normal concentration in all groups of organs for 4 d. The ability of mussels to limit the bioaccumulation of copper and zinc varied from organ to organ, and decreased with higher levels of contamination and longer periods of exposure. In contrast, at the lowest experimental concentration and the lowest period of exposure, a significant increase of cadmium in mussel tissues was generally observed. Even at the highest sub-lethal doses, the levels of copper and zinc in mussel tissues were not much higher than the natural levels (contaminated:background ratios= 2.3 to 6.1), whereas the bioaccumulation of cadmium was less well restricted (contaminated:background ratios=136 to 192). The use of mussels as a bioindicator of pollution seems doubtful for essential metals, particularly as regards short-term pollution, since the levels of these trace elements in the organisms are largely independent of their concentration in the ambient seawater.     

Les variations de la phototaxie des larves de crustacés sous l'action de divers polluants métalliques: mise au point d'un test de toxicité subléthale

Variations in orientation and photokinesis of Carcinus maenas and Palaemon serratus Zoeas I were studied in the presence of excess cobalt and strontium chlorides or silver nitrate. The speed of movement of larvae toward light (phototaxis) appears to constitute a good parameter for testing sublethal toxicity. The salts are toxic to crab larvae in the following decreasing order of toxicity: silver nitrate, cobalt chloride, strontium chloride. Within 4 days, orientation of C. maenas Zoea I was disturbed by excess CoCl₂ and AgNO₃ in the range 0.01 to 0.1 mg/l, and by excess SrCl₂ in the order of 100 mg/l. For P. serratus Zoea I, the corresponding values were 100 to 500 mg/l CoCl₂, 100 mg/l AgNO₃, and above 500 mg/l SrCl₂. C. maenas photokinesis was decreased by amounts of 0.001 mg/l of CoCl₂ or AgNO₃ within a period of only 2 to 3 days.     

Subcellular distribution of zinc and cadmium in the hepatopancreas and gills of the decapod crustacean Penaeus indicus

The decapod crustacean Penaeus indicus accumulated Cd and Zn in different subcellular compartments of hepatopancreas and gill cells. Most of the Cd and part of the Zn accumulates within the soluble fraction of the cells, while the remainder of the Zn is found in insoluble inclusions, associated with P, Ca, Mg and Si in B-, F- and R-cells in the hepatopancreas, and haemocytes, nephrocytes and epithelial cells in the gills. No presence of Cd was observed in metal-rich inclusions in any cell analysed. Metallothionein-like proteins (MTLP), analysed by differential pulse polarography, were present in the hepatopancreas (12–18 mg g⁻¹) and gills (7–8 mg g⁻¹) of metal-exposed prawns. Binding to MTLP is the detoxification mechanism for cadmium, while the detoxification of zinc involves both binding to MTLP and incorporation into insoluble metal-rich inclusions.