Effects of excess selenomethionine on selenium status indicators in pregnant long-tailed macaques (Macaca fascicularis)

Forty pregnant long-tailed macaques were treated daily for 30 d with 0, 25, 150 or 300 μg selenium as L-selenomethionine/kg body weight. Erythrocyte and plasma selenium and glutathione peroxidase specific activities, hair and fecal selenium, and urinary selenium excretion were increased by and were linearly related to L-selenomethionine dose. Hair selenium was most sensitive to L-selenomethionine dose, with an 84-fold increase in the 300 μg selenium/(kg-d) group relative to controls (r=0.917). Daily urinary selenium excretion (80-fold,r=0.958), plasma selenium (22-fold,r=0.885), erythrocyte selenium (24-fold,r=0.920), and fecal selenium (18-fold,r=0.911) also responded strongly to L-selenomethionine. Erythrocyte and plasma glutathione peroxidase specific activities increased 154% and 69% over controls, respectively. Toxicity was associated with erythrocyte selenium >2.3 μg/mL, plasma selenium >2.8 μg/mL, and hair selenium >27 μg/g. Plasma, erythrocyte, and hair selenium concentrations may be useful for monitoring and preventing the toxicity of L-selenomethionine administered to humans in cancer chemoprevention trials.     

Introduction into the ecosystem of the North Sea: Hydrography,biota, and food web relationships

The North Sea, one of the most productive of the earth's seas and oceans, is also surrounded by some of earth's most densely populated and heavily industrialized regions. A growing number of signals are being received which indicate that this valuable ecosystem is increasingly under stress. This has generated a corresponding increase in concern over the steps to be taken to protect the North Sea. While there are divergent views on what constitutes an ‘ideal’ North Sea, there is a general recognition that any decisions that are made should be based on a good understanding of this ecosystem. The intention of this paper is to give an overview of what is presently known, and to identify areas where more studies are needed. A brief summary of the hydrography and the biota of the North Sea is given. Biotic and abiotic structure justify partitioning the North Sea into three ecologically different regions: southern, central, and northern. For the most part, neither the top predators,e.g. marine birds and mammals, nor the macroalgae and sea grasses are included in this overview.     

Quercus ilex browse utilization by Caprini in Sierra de Cazorla and Segura (Spain)

The impact of domestic and wild Caprini browsing on Quercus ilex has been examined in an area of the Sierra de Cazorla. Vegetation as a herbivore food supply, herbivore feeding regime and density in the study area during six sampling periods throughout two years, has been quantified. Wild Caprini show diets similar to the available vegetation, whereas domestic Caprini tend more towards the trophic specialities (browsing or grazing) of their genus. Nevertheless, this tendency was more pronounced in domestic goats than in sheep. A hypothetical estimate of Q. ilex intake by each species under the study conditions was carried out. It was found that domestic Caprini have a greater impact on the holm oak than wild Caprini, density and feeding-niche deviations being the main factors responsible for this situation.Abbreviations DM= dry matter     

Sorption of hydrophobic organic contaminants and trace metals on phytoplankton and implications for toxicity assessment

The partitioning of trace metals and hydrophobic organic contaminants to phytoplankton determines their toxicity as well as their fate and transport in aquatic ecosystems. Accurate impact assessments, therefore, depend on a good understanding of the factors regulating the sorption of these compounds to biotic particles. The accumulation of chlorinated organic compounds in phytoplankton is generally considered as being due solely to physical sorption, described by reversible equilibrium models based on Langmuir or Freundlich isotherms. On the other hand, the uptake of trace metals is a two phase process: a fast sorption component viewed as an ionexchange or a covalent bonding process with cell surface ligands, followed by an intracellular transport phase that is dependent on cellular metabolic activity. The uptake of inorganic and hydrophobic organic pollutants and their bioaccumulation are influenced in a complex manner by duration of exposure and cell density, by environmental factors such as pH, the concentration of cations and of dissolved and colloidal organic matter, as well as by phytoplankton physiological condition. High concentrations of H⁺, Ca²⁺, and Mg²⁺ ions will reduce trace metal sorption by directly competing for uptake sites on the cell's surface, whereas the presence of dissolved organic carbon such as natural and synthetic chelators and phytoplankton exudates will reduce the bioavailability of both trace metals and hydrophobic organic contaminants. Thus, the impact of toxic contaminants on phytoplankton may be determined as much by the factors influencing uptake and partitioning as by the potency of the toxicants and interspecies differences in sensitivity. Recommendations for improving toxicity assessments are presented.     

The effect of trophic/contaminant interactions on chironomid community structure and succession (Diptera: Chironomidae)

The effects of contaminants and organic pollution on the chironomid communities of two basins in Lac St. Louis, a river-lake on the St. Lawrence River above Montreal, Quebec, were assessed and compared using lake classification theory techniques and morphological deformity indices based on the ligulae and antennae ofProcladius, the dominant surviving component of the south-shore communities. Contaminants from the industrial complex around Beauharnois, Quebec, have seriously degraded communities along the south-shore gradient while the introduction of untreated domestic wastes from Laprairie, Quebec, has seriously affected the communities of the Laprairie basin. The interaction between trophic and contaminant effects constitutes a classic example of the setback or deflection in the trajectory of ecological succession in biological communities hypothesized by ODUM (1981, 1985).     

Response of cabbage head weight to simulated Lepidoptera defoliation

Studies were conducted to determine the effects of continuous constant amounts of artificial defoliation through the preheading and heading growth stages on head weight of cabbage. High levels of continuous artificial defoliation caused a reduction in head weight in all three years of the study, but the highest yield was always attained at some low level of preheading or heading defoliation. These results demonstrate that cabbage is tolerant to some levels of continuous defoliation before and after head formation. Results from this study are incorporated into a cost-benefit analysis to estimate an economic threshold.

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Résumé L'étude a porté sur le poids des pommes de choux (Brassica oleracea) soumis à différentes intensités de défoliations répétées avant et pendant la formation des pommes. Pendant les trois années de l'étude, huit intensités de défoliation continue ont réduit le poids des pommes, mais le poids le plus élevé a toujours été obtenu avec une faible défoliation avant et pendant la formation des pommes. Ceci montre que le chou tolère une certaine défoliation avant et pendant la formation des pommes. Les résultats de cette étude ont été utilisés dans une analyse coût-bénéfice pour estimer le seuil économique de défoliation.

     

Pond Acoustic Sampling Scheme: A draft protocol for rapid acoustic data collection in small waterbodies

1. Freshwater conservation is vital to the maintenance of global biodiversity. Ponds are a critical, yet often under‐recognized, part of this, contributing to overall ecosystem functioning and diversity. They provide habitats for a range of aquatic, terrestrial, and amphibious life, often including rare and declining species.
2. Effective, rapid, and accessible survey methods are needed to enable evidence‐based conservation action, but freshwater taxa are often viewed as “difficult”—and few specialist surveyors are available. Datasets on ponds are therefore limited in their spatiotemporal coverage.
3. With the advent of new recording technologies, acoustic survey methods are becoming increasingly available to researchers, citizen scientists, and conservation practitioners. They can be an effective and noninvasive approach for gathering data on target species, assemblages, and environmental variables. However, freshwater applications are lagging behind those in terrestrial and marine spheres, and as an emergent method, research studies have employed a multitude of different sampling protocols.
4. We propose the Pond Acoustic Sampling Scheme (PASS), a simple protocol to allow a standardized minimal sample to be collected rapidly from small waterbodies, alongside environmental and methodological metadata. This sampling scheme can be incorporated into a variety of survey designs and is intended to allow access to a wide range of participants, without requiring complicated or prohibitively expensive equipment.
5. Adoption of this sampling protocol would enable consistent sound recordings to be gathered by researchers and conservation organizations, and allow the development of landscape‐scale surveys, data sharing, and collaboration within an expanding freshwater ecoacoustic community—rather than individual approaches that produce incompatible datasets. The compilation of standardized data would improve the prospects for effective research into the soundscapes of small waterbodies and aid freshwater conservation efforts.

     

Human Health Risk Assessment of Soils Contaminated with Metal(loid)s by Using DGT Uptake: A Case Study of a Former Korean Metal Refinery Site

The human health risk of soils contaminated with As, Pb, Cu, and Zn was evaluated based on pseudo-total concentrations of metal(loid)s, the physiologically based extraction test (PBET), and diffusive gradients in thin films (DGT). Non-carcinogenic (NCR) and carcinogenic (CR) risks exceeded the U.S. Environmental Protection Agency criteria under both the residential and non-residential scenarios. Human bioavailable concentrations (PBET) were much lower than pseudo-total concentrations. The Hazardous Index of NCR (HI (NCR)) for the PBET in the studied soils was 67% and 94% less than that for pseudo-total concentration, respectively, under the non-residential and residential scenarios. Similarly, CR for the PBET was also 65% and 93% less for the two soils. The concentration of metal(loid)s accumulated in the DGT resin was highly correlated with the PBET-extractable concentration (R² > 0.649). Therefore, for both the CR and HI (NCR), the DGT-calculated risk was linearly related to the PBET-calculated risk for the studied soils under both scenarios. The results suggest that DGT uptake and PBET-extracted concentrations are good surrogates for risk estimation and that both J1 and J2 soils require remediation before their use for residential or non-residential purposes.