A one year study of the seasonal variations of sDDT and PCB levels in fish from heated and unheated areas near a nuclear power plant

An investigation of the influence of excess heat discharge from a nuclear power plant on the residual levels of the sDOT and PCB in roach and perch has been made during a period of one year. A seasonal variation of the residual concentrations was observed, with the highest levels during spring and early summer and lower more stable levels in the autumn. Significantly higher levels of the sDDT and PCB was observed in perch from the cooling water recipient as compared to values in perch from the intake area. No significant differences could however be verified for roach. The result stress the importance that, in a monitoring program, a sampling period with stable ecological conditions is selected.     

Responses to projected changes in climate and UV-B at the species level

Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO2 and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO2 enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and "new" species of insects and birds previously associated with areas south of the treeline have been recorded. In contrast, almost all Arctic breeding bird species are declining and models predict further quite dramatic reductions of the populations of tundra birds due to warming. Species-climate response surface models predict potential future ranges of current Arctic species that are often markedly reduced and displaced northwards in response to warming. In contrast, invertebrates and microorganisms are very likely to quickly expand their ranges northwards into the Arctic.     

Reverse quantitative structure-activity relationship for modelling the sorption of esfenvalerate to dissolved organic matter. A multivariate approach

The sorption of the pyrethroid, esfenvalerate, to the dissolved and/or dispersed fraction of eight different natural humic compounds has been investigated. The dissolved organic matters (DOMs) included in this study originate from ground water, soil pore water, and surface waters. Sorption was modelled at DOM concentration levels where equilibrium partitioning of esfenvalerate between DOM and the aqueous bulk phase prevails. The inherent characteristics of the eight different humic materials, quantified in the preceding paper by Thomsen et al. (2002, this issue (PII: S0045-6535(02)00335-1)), have been used as explanatory variables for modelling this equilibrium partitioning. Using a reverse QSAR approach based on by projection-into-latent-structure regression (PLS-R) inherent sorbent properties determining for the sorption affinity of esfenvalerate to DOM were analysed. For all humic substances a decrease in the DOM-normalised equilibrium-partitioning coefficient, K_DOM, with increasing concentration of DOM was observed. Significant variations in K_DOM values, as function of the inherent characteristics of the individual humic substances, were found at DOM concentrations of 75 and 100 ppm, respectively. The latter is a strong indication of variations in sorption mechanisms of esfenvalerate to DOM of varying inherent properties. Groupings in the principal property space quantifying DOMs may indicate that separate models are needed for quantifying the equilibrium partitioning to different classes of DOM.     

Quantifying male attractiveness and mating behaviour through phenotypic size manipulation in the Trinidadian guppy, Poecilia reticulata

Although many studies have examined the effects of male size on attractiveness and mating behaviour, few have taken genetic background into consideration. Phenotypic manipulation permits the experimental adjustment of morphological traits while keeping genetic background constant. Here, male guppies, Poecilia reticulata, an ideal model for this type of manipulation, were raised at different temperatures to produce sibling pairs that differed in size. These were then used to investigate male mating behaviour and male attractiveness, assessed through female mate choice, in relation to this size dimorphism. Further, male–male competition, which is intrinsic to male mating behaviour, is also likely to be affected by their size. Through the use of repeated measures analyses we demonstrate that females significantly prefer larger males and male size and competition significantly affect several aspects of male mating behaviour. Larger siblings perform more sneaky mating attempts and spend more time chasing females. The frequencies of both these behaviours increase with competition. While display frequency is unaffected by male size and competition, display duration and the amount of time spent attending females are reduced in the presence of competitors. This study highlights the use of phenotypic manipulation as a valuable tool for investigating behavioural interactions and confirms that both male size and competition are significant factors in the guppy mating system.     

Sex ratio dynamics and fluctuating selection pressures in natural populations of the Trinidadian guppy,<Emphasis Type="Italic"> Poecilia reticulata</Emphasis>

In many species, population sex ratios have far-reaching consequences for a wide variety of population-level and behavioural processes and can directly influence sexual selection through differential effects on male and female mating behaviour. Although sex ratios are often treated as more or less stable population characteristics, recent theoretical evidence suggests that sex ratios fluctuate under many conditions, and that the amplitude of these fluctuations can be considerable. Few studies have attempted to quantify this variation in systems with prominent, sex ratio-dependent sexual conflict. One of the species with the greatest potential to integrate these factors in the wild is the Trinidadian guppy, Poecilia reticulata. In this study, we quantified natural sex ratio variation both as detailed longitudinal studies of focal guppy populations and as snapshot estimates across a range of freshwater habitats. In line with theoretical predictions, we expected to detect significant sex ratio variation over time. We also investigated the association between juvenile and adult sex ratios to quantify a possible compensatory feedback implied in standard models of sex ratio evolution. Our results confirm that population-level sex ratios in wild guppy populations have a range of dynamic features, with all four focal populations showing significant variation in sex ratio over time. The survey showed that juveniles were generally close to equal (50:50) sex ratios whereas 7 out of 11 adult sex ratios differed significantly from equality. We found no evidence that a surplus of juveniles of the locally rarer sex had been produced. The results indicate that sex ratios and hence the balance between sexual selection and sexual coercion is normally fluctuating in nature, despite juvenile ratios being close to equality.Communicated by J. Krause     

Severity of accidents with hazardous materials A comparison between transportation and fixed installations

A review of accident case histories relevant to hazardous materials has been performed. From the literature, 1793 accident case histories involving hazardous materials were identified, most of them from the period 1960–1988. Of these 1793 accidents, 39% happened during transportation. In 682 accidents the consequences included fatalities, and of these 27% involved the transportation of hazardous materials. The accumulated frequency-fatality curves (so-called fN curves) have been constructed and are close to straight lines with a slope of –1, indicating that the probability of having an accident with, for instance, more than one hundred fatalities is approximately ten times lower than the probability of having an accident with more than ten fatalities. The accidents were grouped according to transportation type, and the difference between the various groups was tested using a standard χ² approach. No significant difference between fixed installations and transportation was found for accidents having consequences above three fatalities. Differences were found between Western Europe and North America and the rest of the world. Once an accident has happened, it seems to have more severe effects outside Western Europe and North America, both for transportation accidents and fixed installations. Comparison of fN curves for Western Europe and North America from different time periods did not show significant differences, indicating that once an accident has happened, it has the same probability of escalating now, as it had 20 years ago.     

An intergrated waste survey and environmental effects of COGIDO, a bleached pulp and paper mill in Vietnam, on the receiving waterbody

An integrated investigation on wastewater characterization and the environmental effects from the COGIDO pulp and paper mill in Bien Hoa Industrial Estate, Vietnam, a chlorine bleached soda integrated pulp and paper mill operating without a chemical recovery system, on the receiving water body was conducted during the rainy and dry seasons in 1993 and 1995. The pollution load from the mill was very high in terms of BOD, COD and SS (COD_m: 58.7 t/d; BOD: 33.3 t/d and SS: 25.1 t/d). The effluent toxicity was determined using four toxicity tests: the green micro-alga, Selenastrum capricornutum, Microtox (marine bacteria: Photobacterium phosphoreum), the duckweed, Lemna aequinoctialis, and fish (silver barb: Puntius gonionotus, and Tilapia: Tilapia nilotica). Selenastrum capricornutum was the most sensitive among the tested organisms. The mill toxicity emission rate (TER) was as high as 338 610 (Selenastrum test). The bleaching-pulp and semi-chemical pulp plants which contributed the largest pollution load to the total COGIDO effluent, therefore, were targeted for abatement measures. Physico-chemical parameters as well as qualitative and quantitative aquatic organism composition for the river water were established. The BOD₅ and COD values exceeded the potable surface water standard by a factor of 2 to 4. The species diversity and abundance of the phytoplankton, zooplankton and zoobenthos were found to be lower (20–40%) than that of unpolluted rivers in Vietnam, whereas pollution-indicator species increased up to four times during the dry season 1995.     

Tourism in the high north: Management challenges and recreation opportunity spectrum planning in Svalbard,Norway

The Arctic is subject to considerable pressure from a rapidly expanding world tourism industry and increasing demands for oil and gas resources. The archipelago of Svalbard in the Norwegian high arctic contains the most accessible islands in the entire Arctic, but despite extensive use of the resources, they still contain some of the last true wilderness lands in Europe. The growth in tourism with visitors from all parts of the world combined with coal mining and oil and gas exploration call for a coordinated environmental policy. A research-based management plan for tourism and recreation has now been developed. Some management problems were encountered in designing a recreation opportunity spectrum plan for this extremely vulnerable environment. Although Svalbard in many ways is a unique area, the challenges to management are comparable to those found in regions further south.