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81.
Katja Schmidt Stephan Pflugmacher Georg B. O. Staaks Christian E. W. Steinberg 《Environmental Sciences Europe》2005,17(3):133-145
Objective and Background
PCB (polychlorinated biphenyle) are typical man-made environmental pollutants that cause a broad spectrum of effects in vertebrates. Although a lot has been studied about the toxic effects of xenobiotic substances on aquatic organisms, their subacute effects are not yet well known. Fish occupies a central position in freshwater food webs and therefore, carp was chosen to be our test organism. The aim of our study was the investigation of subacute effects of Aroclor 1254 (22μg l?1) on respiration, swimming activity, and biotransformation, allowing discussion of changed interaction between the available energy resources.Methods
The respiration experiments under controlled laboratory conditions were run for 29 days (5 d before, 16 d with and 8 d after chemical exposure) with exposed carp compared to the non-exposed fish. Furthermore, the BehavioQuant system quantitatively monitors the positions of each individual fish before (8 d) and during (21 d) PCB exposure and swimming activity (number of horizontal turnings s?1) of animals was calculated. Thereafter, liver samples were taken from animals for analysis of the phase 2 enzyme activity (glutathione-S-transferase). In the respiration experiments were 6 exposure, 6 controll, and 3 solubilizer controll groups (12 animals each group); in the behavioral experiments were 9 exposure, 6 controll- und 3 solubilizer controll groups (6 animals each group), and in the enzyme activity measurements were 9 exposure, 6 controll and 3 solubilizer controll groups (6 animals each group) examined.Results and Discussion
A clearly increased (33%) oxygen consumption due to the PCB-exposure is found to be reversible; after the exposure period the respiration of carp shows a level comparable to the oxygen consumption during non-exposure time. By evaluating quantitative behavioral parameters of animals, it becomes evident that the exposure to PCB also causes a reversible change in their swimming behavior. Chemical stress leads to a decrease of mean daily swimming activity combined with an increase of the mean number of turnings during the night. Thereafter, the swimming activity shifts to the circadian swimming behavior under control conditions. Furthermore, our measurement of soluble and microsomal glutathione-S-transferase activity of fish liver shows a significant elevation after exposure period.Conclusion
Our results prove that it was feasible to detect sublethal effects of PCB-mixture on all parameters under these conditions successfully. Our findings imply that fish are able to cope with the chemicals and we purse the hypothesis that the higher physiological energy demand caused by increased activity of enzymes, which are involved in biotransformation of foregin substances, may be related to a higher respiration of fish stressed by xenobiotics.Recommendation and Outlook
Further experiments should investigate the effects of PCB on ecophysiological parameters of carp fed with exposed natural food allowing discussion of ecological consequences. 相似文献82.
Modelling the responses of the Lagoon of Venice ecosystem to variations in physical forcings 总被引:1,自引:0,他引:1
A Finite Element Ecological Model for the Lagoon of Venice (VELFEEM) has been used to test the responses of the Lagoon of Venice ecosystem to variations in physical conditions.The model is obtained by coupling a finite element hydrodynamic model, that computes the velocity fields of water, an energetic model to compute the water temperature fields, and an ecological model that simulates the dynamic of phytoplankton, zooplankton, nutrients (ammonia, nitrate and phosphate) organic detritus (organic nitrogen, organic phosphorous and CBOD) and dissolved oxygen.The transport model is a two-dimensional barotropic finite element model which allows for a better resolution of the lagoon morphology.The ecological model has been developed by starting from the ecological module EUTRO of WASP (Water Analysis Simulation System released by US EPA), and by adapting it to the peculiarity of the Lagoon of Venice.A reference condition has been identified by running a 1-year simulation under climatologic condition. Then, the sensitivity to physical forcing (tide and wind) and to the input of macronutrients has been investigated, by comparing model predictions of spatial and temporal evolution of major state variables and of an aggregate index of Water Quality Trophic Index (TRIX). 相似文献
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