Identifying the relative importance of predation and resources in population dynamics has a long tradition in ecology, while interactions between them have been studied less intensively. In order to disentangle the effects of predation by juvenile fish, algal resource availability and their interactive effects on zooplankton population dynamics, we conducted an enclosure experiment where zooplankton were exposed to a gradient of predation of roach (<I>Rutilus rutilus</I>) at different algal concentrations. We show that zooplankton populations collapse under high predation pressure irrespective of resource availability, confirming that juvenile fish are able to severely reduce zooplankton prey when occurring in high densities. At lower predation pressure, however, the effect of predation depended on algal resource availability since high algal resource supply buffered against predation. Hence, we suggest that interactions between mass-hatching of fish, and the strong fluctuations in algal resources in spring have the potential to regulate zooplankton population dynamics. In a broader perspective, increasing spring temperatures due to global warming will most likely affect the timing of these processes and have consequences for the spring and summer zooplankton dynamics.

Sampling is a key step in the analysis of chemical compounds. It is particularly important in the environmental field, for example for wastewater effluents, wet-weather discharges or streams in which the flows and concentrations vary greatly over time. In contrast to the improvements that have occurred in analytical measurement, developments in the field of sampling are less active. However, sampling errors may exceed by an order of magnitude those related to analytical processes. We proposed an Internet-based application based on a sampling theory to identify and quantify the errors in the process of taking samples. This general theory of sampling, already applied to different areas, helps to answer questions related to the number of samples, their volume, their representativeness, etc. The use of the internet to host this application facilitates use of theoretical tools and raise awareness of the uncertainties related to sampling. An example is presented, which highlights the importance of the sampling step in the quality of analytical results.

Women are often regarded as counting amongst the most vulnerable social groups. Especially in developing countries, women continue to have fewer rights and access to assets than men. As a con-sequence, women have less access to decent work and are overrepresented in informal work that can weaken the benefits earned through employment. However, for many impoverished women informality offers the only opportunity to make ends meet.<br /> Accordingly, in Côte d’Ivoire women are most present in informal employment. In the city of Abidjan some women make a means of living through extracting valuable waste materials from streets, drains and dumps. These so-called waste pickers rely on waste as the basis of their livelihoods. The-reby, waste picking not only enables the making of livelihoods but also compensates for the failures of the public waste services. As many other rapidly urbanizing areas in developing countries, Abidjan faces the challenges of managing its increasing amount of waste.<br /> This master thesis concerns female waste pickers who work on the waste dump of Akouédo in Abid-jan. It aims to deepen the understanding of women’s livelihoods as informal waste pickers and sheds light on their roles, needs and priorities in the thematic area of waste management in developing countries. [...]<br /><br /> Les femmes sont souvent considérées comme le groupe social le plus vulnérable. Surtout dans les pays en développement, les femmes ont moins de droits et d'accès aux biens que les hommes. En conséquence, les femmes ont des difficultés à trouver un travail décent et sont surreprésentées dans le travail informel, qui peut limiter les avantages sociaux gagnés par l'emploi. Ainsi, en Côte d'Ivoire, les femmes sont les plus présentes dans l'emploi informel. Dans la ville d’Abidjan, certaines femmes gagnent leur vie grâce à la collecte des déchets précieux dans les rues, les caniveaux et notamment les décharges. Ainsi, le ramassage de déchet permet non seulement de créer des moyens d’existence mais aussi de compenser les défaillances des services publics de traitement des déchets. Comme d’autres villes dans les pays en développement qui s'urbanisent rapidement, Abidjan est confronté à gérer la quantité croissante des déchets.<br /> Ce travail de master concerne des ramasseuses de déchets qui travaillent à la décharge d'Akouédo à Abidjan. Il a pour objet l’approfondissement de la compréhension des moyens d’existence de ces femmes et le renseignement de leurs rôles, besoins et priorités liés au thème de la gestion des dé-chets aux pays en développement. [...]

The delta smelt (<I>Hypomesus transpacificus</I>) is an endangered pelagic fish species endemic to the Sacramento?San Joaquin estuary (CA, USA), and considered an indicator of ecosystem health. Copper is a contaminant of concern in Californian waterways that may affect the development and survival of this endangered species. The experimental combination of molecular biomarkers with higher level effects may allow for interpretation of responses in a functional context that can be used to predict detrimental outcomes caused by exposure. A delta smelt microarray was developed and applied to screen for candidate molecular biomarkers that may be used in monitoring programs. Functional classifications of microarray responses were used along with quantitative polymerase chain reaction determining effects upon neuromuscular, digestive, and immune responses in Cu-exposed delta smelt. Differences in sensitivity were measured between juveniles and larvae (median lethal concentration?=?25.2 and 80.4?µg/L Cu<SUP>2+</SUP>, respectively). Swimming velocity declined with higher exposure concentrations in a dose-dependent manner (<I>r</I>=-0.911, <I>p</I><0.05), though was not statistically significant to controls. Genes encoding for aspartoacylase, hemopexin, α-actin, and calcium regulation proteins were significantly affected by exposure and were functionally interpreted with measured swimming responses. Effects on digestion were measured by upregulation of chitinase and downregulation of amylase, whereas downregulation of tumor necrosis factor indicated a probable compromised immune system. Results from this study, and many others, support the use of functionally characterized molecular biomarkers to assess effects of contaminants in field scenarios. We thus propose that to attribute environmental relevance to molecular biomarkers, research should concentrate on their application in field studies with the aim of assisting monitoring programs.

A new method was developed for the analysis of natural and synthetic androgenic steroids and their selected metabolites in aquatic environmental matrixes using direct large-volume injection (LVI) high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). Method accuracy ranged from 87.6 to 108% for analytes with well-matched internal standards. Precision, quantified by relative standard deviation (RSD), was less than 12%. Detection limits for the method ranged from 1.2 to 360 ng/L. The method was demonstrated on a series of 1 h composite wastewater influent samples collected over a day with the purpose of assessing temporal profiles of androgen loads in wastewater. Testosterone, androstenedione, boldenone, and nandrolone were detected in the sample series at concentrations up to 290 ng/L and loads up to 535 mg/h. Boldenone, a synthetic androgen, had a temporal profile that was strongly correlated to testosterone, a natural human androgen, suggesting its source may be endogenous. An analysis of the sample particulate fraction revealed detectable amounts of sorbed testosterone and androstenedione. Androstenedione sorbed to the particulate fraction accounted for an estimated 5 to 7% of the total androstenedione mass.

Vorwort zur Sondernummer "Wasser" der Ciba Hauszeitschrift.

Drains can be installed to reduce saturated soil condi-tions and improve crop growth. This article evaluates the extent to which these systems may cause losses of plant protection products (PPP). To that end, we esti-mated the drained fraction of Swiss arable land using both existing drainage maps and machine learning. Our drainage map suggests that 25% of Swiss agricultural land has a moderate to high potential of being drained. We further evaluated the risk for PPP losses via drainage and the potential of selected mitigation measures based on a conceptual model summarising the relevant scientific literature. Although drainage losses are highly variable, they are strongly influenced by the extent of preferential flow (PF) in soils and are an important transport pathway to surface waters. Most agricultural soils in Switzerland are prone to PF, given their loamy texture, suggesting that PPP losses via tile drains are an important phenomenon in Swit-zerland’s drained arable fields. The most common mitigation measures for drainage are those recommend-ed for runoff, erosion and leaching. However, given the uncertainty of the local PPP losses and driving factors, no site-or PPP-specific measures can currently be proposed to reduce PPP drainage losses. This study also examines the effectiveness of the regulatory model EXPOSIT in predicting total PPP losses and peak concentrations in watercourses. When compared with experimental data from Agroscope at Zurich-Affoltern, our findings suggest that EXPOSIT does not yield the worst-case estimates for Swiss conditions.