Der Fischrückgang in der oberen Donau

Background During the last years, a decrease in fish populations has been documented for several river systems in Europe and North America. Since more than 20 years, similar developments have been documented for the upper Danube River between Sigmaringen and Ulm. The grayling (Thymallus thymallus) represents one of the most affected fish species in the upper Danube, and notable decrease has also been recorded for other species such as the European barbel (Barbus barbus). Despite intensive and continuous stocking and improvement of water quality along the Danube since the 1970s, this negative development of fish populations could not be stopped. Aim This article has been designed to give an overview on various investigations into the decline of fish in the upper Danube River. The major focus of this paper is on the presentation of a weight-of-evidence study carried out since 2003 at the Department of Zoology at the University of Heidelberg. Results and discussion During the 1920s, major parts of the upper Danube River were corrected, thus causing dramatic changes in the hydromorphology of the river. The macrozoobenthos, which represents an important source of nutrition for several fish species, depends on the morphological conditions of a river; recent investigations, however, could not show any dramatic changes in macrozoobenthos composition. Earlier investigations of the Danube River primarily focused on water quality, which has, indeed, been continuously improved by extensive modernization of wastewater treatment plants. Contamination by priority organic pollutants in sediments was not given any attention until the mid 1990s, when a clear decline of, e.?g., PAH concentrations were documented. However, results of more recent analyses showed very high PAH concentrations in two sediment samples (Schwarzach Σ 16 PAHs = 26 mg/kg; Öpfingen Σ 16 PAHs = 5 mg/kg). In 2002, the first ecotoxicological investigations were performed at the upper Danube River. The results of a pilot study showed a high ecotoxicological burden for selected sampling sites. As a conclusion of this study, a weight-of-evidence investigation was initiated to make an attempt to identify major pollutants and possible causes for the fish decline. In addition to, e.?g., liver ultrastructure analyses in barbel, the micronucleus test was used as a definite mutagenicity test using erythrocytes and liver samples. The results of the different in vitro tests showed very good correlation well with in situ parameters. Outlook The investigations within this weight-of-evidence study showed that the pollution situation of the Danube is, indeed, significant enough to potentially affect fish populations. However, further investigations are needed to clarify the specific causes for the fish decline. A bioassay-directed fractionation study is underway to identify specific pollutants as well as their sources. This study will also assess the endocrine disrupting potential of Danube sediments via histopathological analyses of gonads of field fish in combination with different in vitro tests. Furthermore, in the planned joint project COMPSEARCH, comparative investigations will evaluate the ecotoxicological hazard potential of different pollution sources and consequences of changes in land use.     

Fischpopulationen unter Stress – das Beispiel des Unteren Neckars

Background, aim, and scope Reports about declines or unusual structures of fish populations in native aquatic systems in Central Europe and North America are in sharp contrast to an obvious improvement of general water quality. The Neckar River may serve as an example of a formerly severely contaminated freshwater system in Southern Germany, the ecological situation of which could be substantially improved over the last three decades. Nevertheless, there are still deficits in the composition of the fish fauna, which cannot be explained by conventional chemical-analytical, hydromorphological and limnological methodologies. Therefore, in search of explanations for ecological deficits, ecotoxicological investigations with an increasing focus on sediment contamination have been performed along the Lower Neckar River over a period of 10 years. In addition to sediment tests, fish populations were screened for genotoxic and embryotoxic effects as well as alterations in the structure of central metabolic organs such as the liver. Materials and methods Roach (Rutilus rutilus) and gudgeon (Gobio gobio) from the Lower Neckar River were studied with respect to histo- and cytological alterations of the liver as well as the induction of genotoxicity in liver, gut, gills and blood cells by means of the comet and micronucleus assays. At the same time, both native sediments and acetonic sediment extracts were tested for toxicity to zebrafish (Danio rerio) embryos and permanent fish cell cultures. Results Massive disturbances of the liver ultrastructure indicate severe stress in the fish from the Lower Neckar River despite good supply of nutrition. Both cyto- and embryotoxicity tests document a considerable toxic potential of sediments from the Lower Neckar River, and results of both the comet assay and the micronucleus test provide evidence of the presence of genotoxic agents in the sediments and their effects in fish. There has been no decrease of genotoxicity over the last 10 years. Discussion Cytopathology in conjunction with general cyto- and embryotoxicity in fish from the Lower Neckar River contribute to a syndrome which cannot be neglected in the interpretation of abnormal compositions of fish populations. In comparison to weight-of-evidence studies at other river systems in Southern Germany, the Neckar is characterized by an elevated embryotoxic but by a relatively moderate genotoxic potential. Conclusions The ecotoxicological burden of sediments at the Lower Neckar River is mirrored in the condition of native fish populations. A potential contribution of chemical contamination to the phenomenon of fish declines in aquatic ecosystems cannot be ignored. Recommendations and perspectives The improvement of the ecological status of freshwater systems may not be abused as an argument to discontinue biological monitoring programs. Rather, continuous surveillance of the environment and in-depth investigations into the consequences of chemical contamination are indispensible. For an adequate appreciation of the ecological relevance of sublethal and/or specific biological effects, their impact on population structure and function remains to be elucidated further. For the identification of the chemical basis of biological effects, methodologies such as effect-directed analysis appear to be promising approaches.     

Life cycle assessment and sustainable engineering in the context of near net shape grown components: striving towards a sustainable way of future production

Technical product harvesting (TEPHA) is a newly developing interdisciplinary approach in which bio-based production is investigated from a technical and ecological perspective. Society‘s demand for ecologically produced and sustainably operable goods is a key driver for the substitution of conventional materials like metals or plastics through bio-based alternatives. Technical product harvesting of near net shape grown components describes the use of suitable biomass for the production of technical products through influencing the natural shape of plants during their growth period. The use of natural materials may show positive effects on the amount of non-renewable resource consumption. This also increases the product recyclability at the end of its life cycle. Furthermore, through the near net shape growth of biomass, production steps can be reduced. As a consequence such approaches may save energy and the needed resources like crude oil, coal or gas. The derived near net shape grown components are not only considered beneficial from an environmental point of view. They can also have mechanical advantages through an intrinsic topology optimization in contrast to common natural materials, which are influenced in their shape after harvesting. In order to prove these benefits a comprehensive, interdisciplinary scientific strategy is needed. Here, both mechanical investigations and life cycle assessment as a method of environmental evaluation are used.     

Comparison of sewage sludge toxicity to plants and invertebrates in three different soils

Understanding the effect of soil type on the overall toxicity of sewage sludge is one of the most important issues concerning environmental risks associated with the sewage sludge land application. The aim of the study was to determine the influence of different soils (sandy, loamy and OECD soil) on sewage sludges toxicity in relation to plants (Lepidium sativum, Sorghum saccharatum, Sinapis alba) and an invertebrate species (Heterocypris incongruens). The most evident negative influence of sewage sludges on root growth was observed in the case of OECD soil. The EC(50) values determined on the basis of the root growth inhibition of all tested plants were in the range 0.1-6.4%, 0.03-9.4% and 6.6-22.1% (% of sewage sludgekg(-1) soil) for OECD, sandy and loamy soil, respectively. Soil type also affects the sewage sludge toxicity in relation to H. incongruens. The LC(50) (mortality) values ranged from 0.26% to 11.5% depending on the sludge tested. For EC(50) (growth inhibition) values ranged from 10.7% to 36.2%.     

The OECD validation program of the H295R steroidogenesis assay: Phase 3. Final inter-laboratory validation study

Background, goals, and scope

In response to increasing concerns regarding the potential of chemicals to interact with the endocrine system of humans and wildlife, various national and international programs have been initiated with the aim to develop new guidelines for the screening and testing of these chemicals in vertebrates. Here, we report on the validation of an in vitro assay, the H295R steroidogenesis assay, to detect chemicals with the potential to inhibit or induce the production of the sex steroid hormones testosterone (T) and 17??-estradiol (E2) in preparation for the development of an Organization for Economic Cooperation and Development (OECD) test guideline.

Methods

A previously optimized and pre-validated protocol was used to assess the potential of 28 chemicals of diverse structures and properties to validate the H295R steroidogenesis assay. These chemicals are comprised of known endocrine-active chemicals and ??negative?? chemicals that were not expected to have effects on the targeted endpoints, as well as a number of test chemicals with unknown modes of action at the level of the steroidogenic pathway. A total of seven laboratories from seven countries participated in this effort. In addition to effects on hormone production, confounding factors, such as cell viability and possible direct interference of test substances with antibody-based hormone detection assays, were assessed. Prior to and during the conduct of exposure experiments, each laboratory had to demonstrate that they were able to conduct the assay within the margin of predefined performance criteria.

Results

With a few exceptions, all laboratories met the key quality performance parameters, and only 2% and 7% of all experiments for T and E2, respectively, were excluded due to exceedance of these parameters. Of the 28 chemicals analyzed, 13 and 14 tested affected production of T and E2, respectively, while 11 and 8 did not result in significant effects on T and E2 production, respectively. Four and six chemicals produced ambiguous results for effects on T and E2 production, respectively. However, four of these cases each for T and E2 were associated with only one laboratory after a personnel change occurred. Significant interference of test chemicals with some of the antibody-based hormone detection systems occurred for four chemicals. Only one of these chemicals, however, significantly affected the ability of the detection system to categorize the chemical as affecting E2 or T production.

Discussion and conclusions

With one exception, the H295R steroidogenesis assay protocol successfully identified the majority of chemicals with known and unknown modes of interaction as inducers or inhibitors of T and E2 production. Thus it can be considered a reliable screen for chemicals that can alter the production of sex steroid hormones. One of the remaining limitations associated with the H295R steroidogenesis assay protocol is the relatively small basal production of E2 and its effect on quantifying the decreased production of this hormone with regard to the identification of weak inhibitors. An initial comparison of the data produced in this study with those from in vivo studies from the literature demonstrated the potential of the H295R steroidogenesis assay to identify chemicals affecting hormone homeostasis in whole organisms. Particularly promising was the lack of any false negatives during the validation and the very low number of false positives (1 out of 28 chemicals for each T and E2).

Perspectives

Based on the results obtained during this validation study and the accordingly revised test protocols, an OECD draft test guideline was developed and submitted to the OECD working group of the national coordinators of the test guidelines program (WNT) for comments in December 2009.     

Verantwortungsvoller Umgang mit der Ressource Boden – Workshop zur Erarbeitung eines Aachener Modells für ein nachhaltiges Landmanagement am Niederrhein

Ohne Zusammenfassung