Armin Peter

Characterization of the estrogenicity of Swiss midland rivers using a recombinant yeast bioassay and plasma vitellogenin concentrations in feral male brown trout

In our study, we aim to characterize the estrogenicity of 18 independent rivers that receive effluent from sewage treatment works. During the winter and summer of 2003, we collected multiple water samples and measured environmental estrogens with an in vitro yeast-based reporter gene assay; estrogenicity was expressed as ng 17beta-estradiol equivalents (EEQ) per L of water. Estradiol equivalents values in winter ranged from 0.3 to 2.0 ng/L and, in summer, from 0.4 to 7.0 ng/L. Winter and summer EEQ values were not correlated with each other or with the dilution factor of the effluent in the river. Variation in EEQ values was large and correlated from winter to summer. Part of this variation in estrogenicity is explained by water flow rates; variation is larger at reduced flow rates. We measured plasma vitellogenin concentrations in immature male brown trout. At five sites, vitellogenin concentrations exceeded 1 microg/ml; however, at the majority of the sites, plasma vitellogenin concentrations were below 0.5 microg/ml. Our data indicate that the exposure of brown trout to environmental estrogens in Swiss midland rivers is low. However, some sites show reoccurring higher EEQ values and, at some sites, plasma vitellogenin concentrations in male fish clearly are elevated.

Stress status of gudgeon (Gobio gobio) from rivers in Switzerland with and without input of sewage treatment plant effluent

To assess the importance of sewage treatment plant effluents on fish health, we studied gudgeon in two rivers in the Swiss midlands (Canton Lucerne). Both rivers receive pollution from diffuse sources, while one also receives the effluent of a sewage treatment plant. Male and female gudgeon during and outside of the spawning season were compared with respect to reproductive parameters and health status across both rivers as well as upstream and downstream of the STP. Several biomarkers were studied, including cytochrome P4501A, 7-ethoxyresorufin-O-deethylase, plasma vitellogenin, ovotestis, lipid, liver histology, condition factor, gonadosomatic index, splenosomatic index, parasites of spleen and liver, population structure, and species diversity. Gudgeons of both rivers exhibited signs of a moderately impaired health status. By a stepwise backward analysis, the cytochrome P4501A content, the splenosomatic index, and the incidence of parasites in the liver were found to provide the best discrimination of the three sampling sites. Evidence of a significant elevation in response to the sewage treatment plant effluent was found neither in vitellogenin concentration nor in the ovotestis rate. While population structure was analyzed upstream and downstream of the sewage treatment plant, only gudgeons of the latter site revealed a disturbed population structure, most probably caused by a former nitrite discharge.

Green Hydropower: The contribution of aquatic science research to the promotion of sustainable electricity

Abstract. Hydropower use is responsible for a wide range of environmental disturbances to river systems. Over the past decades, aquatic science research has been successful in identifying a considerable number of relationships that exist between plant operation and ecosystem quality. This increase in scientific knowledge was, however, not matched by a corresponding reduction in environmental impacts stemming from hydropower. In the present paper, we show how aquatic science projects may be defined and implemented to better link scientific knowledge with the resolution of environmental problems.¶We base our analysis on a major aquatic science research project in which an eco-label for “sustainable hydropower” (Green Hydropower) was developed for Switzerland. We first assess the state of aquatic science research on alpine river systems. The Swiss history of hydropower shows that the limited adoption of this knowledge was due to a severe coordination and action problem. The Green Hydropower project aimed at establishing an environmental product label for hydropower plant operation, which should help overcome these problems. It had to deal with two major challenges: the integration of widely differing knowledge stocks and the management of a network of diverse stakeholders operating in a conflict-laden political environment. By carefully dealing with these two problem areas, the project was finally able to define a scientifically-based and broadly-accepted standard for Green Hydropower operation. We conclude by discussing lessons for the improvement of problem-oriented aquatic science research, in general.

River fragmentation increases localized population genetic structure and enhances asymmetry of dispersal in bullhead (Cottus gobio)

Man-made habitat fragmentation is a major concern in river ecology and is expected to have particularly detrimental effects on aquatic species with limited dispersal abilities, like the bullhead (Cottus gobio). We used ten microsatellite markers to investigate small-scale patterns of gene flow, current dispersal and neutral genetic diversity in a morphologically diverse river where fragmented and unfragmented sections could be compared. We found high genetic differentiation between sampling sites with a maximum FST of 0.32 between sites separated by only 35 km. A significant increase of genetic differentiation with geographical distance was observed in the continuous river section as well as in the full dataset which included headwater populations isolated by anthropogenic barriers. Several lines of evidence are consistent with the hypothesis that such barriers completely block upstream movement while downstream dispersal may be little affected. In the unfragmented habitat, dispersal rates were also higher in the direction of water flow than against it. The resulting asymmetry in gene flow likely contributes to the decrease of genetic variation observed from the lower reaches towards the headwaters, which is particularly pronounced in physically isolated populations. Our findings suggest that headwater populations, due to their isolation and low genetic variation, may be particularly vulnerable to extinction.

Scientific base and modular concept for comprehensive assessment of streams in Switzerland

There is a difficult polarity between reality and ecologically desirable goals of stream ecosystem management in Switzerland. Most streams are exposed to a variety of impacts. Due to a high intensity of anthropogenic activity there is a high pressure on land and water use. Essential water uses have to be guaranteed. On the other hand there is also a strong need to preserve or restore (bring back ecological integrity) or rehabilitate streams (bring back ‘relative ecological integrity’). Stream assessment should, therefore, produce sound data suitable for characterizing the ecological condition of streams and for supporting their sustainable management. The methods should include a system approach as the basic unit and sound scientific principles of ecological integrity emphasizing habitat connectivities. The methods should allow: • the condition of streams to be rationally described and judged, • identification of different kind of impacts on a stream, • verification of the effects of water protection measures, • identification of suitable future actions in the context of a whole stream system. In order to cover the various requirements a modular concept for stream system-oriented analysis was developed. Altogether nine modules are elaborated. Each module deals with specific stream features (two hydrodynamic and ecomorphological modules, five biological modules, two chemical and ecotoxicological modules). Single modules, several modules, or all of them may be applied, depending on the purpose of the analysis. For each module a cost-effective survey procedure (rapid method) and a progressively more rigorous method providing more detailed information is suggested. Based on the result of the analysis, stream rehabilitation concepts can then be elaborated in cooperation with managers, river engineers and biologists.

Sensitivity of brown trout reproduction to long-term estrogenic exposure

A decline in brown trout (Salmo trutta fario) catches has been reported in Switzerland, but at present the causative factors have not been clearly identified. Estrogen-active endocrine disrupters (EEDs) have been suggested as one possible explanation, since they are widespread in the aquatic environment and often found at elevated concentrations. In the present study the effects of long-term estrogenic exposure on the reproductive capability of brown trout were investigated. Adult fish were continuously exposed to an environmentally relevant mixture of the natural estrogens estrone (E1), 17beta-estradiol (E2) and the xenoestrogen 4-nonylphenol (NP); the average measured concentrations over the entire exposure time (n=9) were 14.0 ng/l (Min 8.1 and Max 20.6) for E1, 2.1 ng/l (Min 1.3 and Max 4.1) for E2 and 111.0 ng/l (Min 106.7 and Max 115.9) for NP. A solvent control served as negative control, and up to 10-fold higher mixture concentration than the environmentally relevant concentration served as positive control. The fish were exposed for 150 days from the onset of gonadal recrudescence until sexual maturation. Plasma vitellogenin (Vtg) was significantly induced by both concentrations of the estrogenic mixture, whereas effects on growth and fertility were only observed in fish exposed to the high mixture treatment. Fertilization success and offspring hatchability in brown trout exposed to the high mixture treatment were significantly reduced to 9% and 6%, respectively. Developmental time from fertilization until hatching, the percentage of larvae with malformations and survival of larvae, however, were not affected. The results suggest that a combination of estrogen-active compounds at environmentally relevant concentrations would not adversely affect those parameters of brown trout reproductive capability measured in this study. Plasma Vtg in male brown trout appeared to be more sensitive to (xeno)estrogen exposure than the measured reproductive effects.

Status of young-of-the-year brown trout (Salmo trutta fario) in Swiss streams: factors influencing YOY trout recruitment

Abstract.As part of the Swiss Fischnetz project (network for declining fish yields in Switzerland) studies were carried out to investigate the decline in catches of brown trout. Insufficient YOY (young-of-the-year) recruitment of brown trout due to different abiotic and/or biotic factors was hypothesized as a potential cause of this decline. Quantitative assessments of fish ecology parameters and habitat measurements were carried out at 97 river sites over a two-year period. The main objectives of this study were to document the occurrence and abundance of naturally reproduced YOY trout and to develop an understanding of environmental factors responsible for the observed YOY density. A general linear model (GLM) was used to analyse the influence of selected environmental abiotic and biotic parameters on YOY density.Successful recruitment of YOY trout was observed in all but three of the sites studied. Abundance was correlated with abiotic and biotic factors, such as river width, slope, altitude, substratum condition, and the occurrence of proliferative kidney disease (PKD). The results highlight the importance of small streams for natural YOY recruitment of brown trout and their function as a source of individuals for downstream river sections.

Fish community responses and the temporal dynamics of recovery following river habitat restorations in Europe

Considerable uncertainty exists regarding the ability of reach-scale habitat restorations to promote ecological integrity and affect community composition in degraded streams and rivers and the time scales at which these effects take place. Restoration of habitats on the reach scale (hundreds of meters to a few kilometers) is expected to support threatened species because many of them are habitat specialists. In contrast, generalist species are predicted to be replaced in restored reaches. We used a large data set for 62 reach-scale restoration projects in 51 stream systems in Germany, Switzerland, and Liechtenstein and analyzed the changes in fish community composition induced by the restorations in terms of species richness, species turnover, Brillouin diversity index, total fish abundance, and proportion of alien and endangered species. We further analyzed the temporal dynamics of the fish community recovery over a period of 19 y postrestoration. Species richness and Brillouin diversity index increased in most of the restoration projects (66 and 57%, respectively), but recovery to historical reference conditions was not achieved. Total abundance was enhanced by most of the projects. Species composition in restored reaches underwent directed shifts for at least 10 y, with high and variable species turnover in the first years that decreased over time. The effects of restoration on Brillouin diversity index were highly variable in the first few years after restoration, but tended to increase over time. These dynamics must be considered more carefully in future protocols for evaluating restoration results, and final evaluation of restoration outcomes on fish communities should not be made too early. Our results indicate that reach-scale habitat restorations may be a suitable tool for increasing local fish abundance and slightly enhancing species diversity. However, more targeted approaches are needed to support threatened species and repress alien species.

Moving targets, long-lived infrastructure, and increasing needs for integration and adaptation in water management: an illustration from Switzerland.

Switzerland provides an example of successful management of water infrastructure and water resources that was accomplished largely without integration across sectors. Limitations in this approach have become apparent; decisions that were formerly based only on technical and economic feasibility must now incorporate broader objectives such as ecological impact. In addition, current and emerging challenges relate to increasingly complex problems that are likely to demand more integrated approaches. If such integration is to be of benefit, it must be possible to redirect resources across sectors, and the synergies derived from integration must outweigh the additional cost of increased complexity.

Success or Failure? : Do Indicator Selection and Reference Setting Influence River Rehabilitation Outcome?

Abstract Recovery indicators play a crucial role in the evaluation of river rehabilitation projects. Various types of biological indicators are used to address different ecosystem attributes (structure, composition, and function) at different levels of the biological hierarchy (population, guild, and community). Indicator values are evaluated against reference information from various sources, representing the conditions to be achieved (near-natural references) or to avoid (degraded references). We studied the extent to which investigators’ conclusions on project outcome were influenced by the indicator and reference types used. We analyzed 40 selected studies dealing with the recovery of riverine fish assemblages after active rehabilitation of physical habitat and lateral connectivity. In 32 (80%) of the 40 studies, fish response was measured at the population level. Structural and compositional indicators dominated (31 and 24 studies, respectively), while functional indicators were underrepresented (5 s...