Organochlorverbindungen in Eiern von Wanderfalken und anderen wild lebenden Vogelarten in Baden-Württemberg

Goal and Scope

Organochlorine pollutants such as some pesticides and polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/F) are highly persistent compounds in the environment. As synthetic, man-made products they are not encountered in natural ecosystems. Due to their high lipid solubility these compounds can accumulate in animals and humans, where they may exert chronically toxic and carcinogenic effects or disrupt endocrine functions and/or interfere with reproduction. Sound environmental stewardship demands continuous monitoring of such substances, assessment of their ecotoxicological risk, and reduction of excessive risk by setting appropriate standards.

Methods

The analysis of birds’ eggs is one method for the detection of organochlorine pollutants in ecosystems. In the German state of Baden-Wuerttemberg eggs of some bird species, especially Peregrine falcons, have been collected and analysed for selected persistent organic pollutants [total DDT (dichlorodiphenyl-trichloroethane), HCB (hexachlorobenzene), HCEP (heptachloroepoxide), HCH (hexachlorocyclohexane), PCBs] since the 1970s. Long-term continuous investigations yield data concerning temporal changes and regional differences in the pollution of the bio-indicators.

Results and Conclusion

Dioxin-like PCBs and total DDT were the most prominent pollutants. The Peregrine falcon (Falco peregrinus) was the most polluted bird species within the project. During the 1970s and 1980s all of the mentioned substances showed an encouraging decrease, undoubtedly because their use was banned in Germany. Analyses for PCDD/F in a small number of Peregrine falcon eggs from the period of 2000 to 2003 revealed the high level of pollution of these samples with dioxin toxicity equivalents (WHO-TEQ) from PCB and PCDD/F, which in all eggs reached the no observed effect level (NOEL) determined in osprey chicks and surpassed this threshold fivefold in the most polluted one.. Because of their great variability the pollutant concentrations in the eggs were difficult to interprete in some cases. Based on the results for the Peregrine falcon eggs of the years 2001 to 2003 a statement concerning the regional distribution of DDT and PCBs in Baden-Wuerttemberg could be made and depicted on the map. Because of their high lipid content, birds’ eggs are generally well suited as bio-indicators for the accumulation of persistent and lipophilic compounds.

Recommendations and Perspective

In spite of the significant decline of the organochlorine concentrations in the eggs of the birds investigated, the present situation is still alarming. Too many of the analytical data continue to exceed the respective national and EU-wide limit values for food and feed, and in the case of dioxin equivalents even lie above the assumed action threshold in the indicator organism. Therefore it is necessary to continue the bio-monitoring in Baden-Wuerttemberg in order to be able to recommend reduction measures where appropriate.     

Species recognition and species isolation in wandering spiders (Cupiennius spp.; Ctenidae)

Summary One of the roles ascribed to spider courtship is that of mate recognition and reproductive isolation. We describe behavioral mechanisms underlying these functions in three species of wandering spiders of the genus Cupiennius (Ctenidae). C. salei and the two sympatric species C. getazi and C. coccineus discriminate conspecifics and heterospecifics in a multistage process which covers three principal phases of courtship: (1) Chemical phase: male spiders initiate vibratory courtship communication less often upon contact with heterospecific than with conspecific female silk. (2) Vibratory phase: females respond with their own vibration less often and with increased delay to the vibratory courtship signals of heterospecific males than to those of conspecific males. (3) Tactile phase: in heterospecific pairings males and females interrupt the contact phase if their courtship has progressed thus far. The product of the probabilities of passing through each of the different stages of courtship is between 0.44 and 0.88 for conspecific pairings, but zero for most heterospecific pairings. This is to a greater extent due to the behavioral barriers of the vibratory and the tactile phase than to that of the chemical phase. Male taxis on tracks of female silk does not depend on the species-specificity of the silk. Female vibrations are not essential for species recognition: males increase their signal rates, orient toward and approach responding females in both con- and heterospecific pairings. Female attacks on males are similar to attacks on prey; males defend themselves with outstretched front legs and are caught and killed by the female in only 5% of the cases. In all phases of courtship, female C. salei are least and female C. getazi most selective. When female C. coccineus and C. getazi are involved in heterospecific pairings no copulation is attempted. In contrast, 13 copulations of C. salei with males of the other two species were observed; egg sacs never resulted from these copulations. Among males, those of C. getazi were least selective. The likelihood of heterospecific pairs passing through all phases of courtship is higher in case of the allopatric than in that of the sympatric species. This finding applies to the courtship as a whole, but not necessarily to each of its phases.Offprint requests to: F.G. Barth     

Idiothetic orientation of a wandering spider: Compensation of detours and estimates of goal distance

Summary The wandering spider Cupiennius salei Keys uses idiothetic orientation, i.e., memorized information about its own previous movements, to retrieve lost prey. Spiders, having been chased away from a prey fly, return to the capture site (the goal) over a distance of more than 75 cm even though all external orientation cues were precluded. This behavior and its sensory basis were examined by varying the proprioceptive and motor command inputs to the memory and by ablating particular lyriform slit sense organs on the legs of the spider.The success rate of returns to the goal after rectilinear chases over 6 discrete distances ranging from 20 cm to>41 cm declines with increasing distances. At distances>41 cm, more than 50% of the performances of intact spiders are nevertheless successful, in that the animals approach the capture site as close as 5 cm (or less).Animals that have been operated on (lyriform organs on all femora destroyed) are much less successful even at short distances. The mean starting angles of the returns by intact spiders and by those operated on do not differ signficantly. Walking error e _n for each segment of the entire return path shows that intact animals deviate little from the ideal return route and correctly estimate the distance to the goal. The operated spiders tend to drift off the ideal return route, while their distance estimates remain largely accurate.Returns after curvilinear chases through a semicircular corridor do not retrace the curved path; instead the spiders take a shortcut. Of all performances by intact and by control spiders (with sham operations) 85% are successful. By contrast, most of the 8 groups with sensory ablations have a success rate of less than 50%.Compensation for the semicircular detours is not quite complete: the mean starting directions of returns are biased, pointing to the corridor, and the shape of many return paths reflects the curved corridor shape. Spiders with unilateral ablations of their femoral lyriform organs show low success rates only if the operated legs are on the inner curve perimeter during the chase, while their return parameters resemble those of the intact group in the reverse situation (operated legs on outer perimeter). These side-specific ablation effects, which are correlated with the geometrical situation existing while idiothetic information is gathered and memorized, suggest that the idiothetic memory depends at least partly on input from proprioceptors.     

Simulation of aquatic food web and species interactions by adaptive agents embodied with evolutionary computation: a conceptual framework

Individual-based and state variable-based adaptive agents (AA) are discussed regarding their relevance to different types of ecosystems. Individual-based AA proved applicable to a spatially explicit simulation of highly simplified terrestrial food webs. State variable-based AA with evolutionary computation (EC) embodied are suggested for the simulation of aquatic food webs and plankton species interactions. Embodiment of EC in AA can be achieved by evolving predictive rules (ER), differential equations (EDE) or artificial neural networks (ANN) derived from a diverse lake database. In order to provide ecosystem simulation with resilience to environmental change, agent banks can be created containing alternative agents for same species or functional groups from different lakes. State variable-based AA are currently tested for aquatic ecosytem simulation by means of a diverse lake database. It promises to overcome constraints by the rigidity of traditional lake ecosystem models.     

Rationale Suche nach Ersatzmethoden für Tierversuche

Naturwissenschaften Aktuell

Rationale Suche nach Ersatzmethoden für Tierversuche     

Prenatal diagnosis of a 46,XX/47,XX, +12 mosaic

A case of true mosaicism 46,XX/47,XX,+ 12 was diagnosed prenatally. The pregnancy was terminated in the 21st week of gestation and the aberrant cell line was rediscovered in cultured fetal tissue. However, a detailed examination of the fetus did not disclose any significant physical malformation.