Schwermetalle und organische Umweltchemikalien in Rehwild (Capreolus capreolus L.) aus Forst- und Agrarstandorten

The roe deer indicates the contamination of ecosystems with environmental chemicals. The influence of land use on the contamination of five different forest and agricultural ecosystems in Rheinland Pfalz was proven. The cadmium and lead content was measured in renal tissue of the roe deer. The organic chemicals PCB, α-HCH, Lindan, DDT, and DDE were investigated in kidneys and liver and correlated to adipose tissue. The following results have been obtained: Lead: The Pb-contamination was generally low in all ecosystems investigated. Cadmium: The Cd-values showed an area-dependend contamination of the organs. The data of the test organs from the forest sites and the semi-agricultural area were 2–4 times higher than the ZEBS-limit. The contamination of the animals corresponded to the wet deposition of Cd in the regions. σPCB: The PCB-results indicated a relativly high contamination of the ecosystems. The PCB-ZEBS-limit for the interior organs was surpassed in all areas.α-HCH, γ-HCH (Lindan): The uniformly low values of the HCH-group indicated that these compounds were probably not of ecotoxicological significance in the agricultural and forest regions.DDT, DDE: The results obtained showed a low background contamination in all ecosystems investigated. Areas with former high DDT-applications revealed higher values of DDE in the tissues. ZEBS: Central institution for the evaluation of chemicals in the environment (Bundesgesundheitsamt)     

The metabolization of lindane in a culture of mould and the degradation scheme of lindane

The metabolism of Lindane, gamma-Pentachlorcyclohexene and isomeric Tetrachlorobenzenes in a culture of Mould was investigated in this work. 1,2-, 1,4-Dichlorobenzene, 1,2,3-, 1,2,4-, 1,3,5-Trichlorobenzene, 1,2,3,4-, 1,2,4,5- and/or 1,2,3,5-Tetrachlorobenzene, Pentachlorobenzene, gamma-Pentachlorocyclohexene, Hexachlorobenzene, Tetrachlorocyclohexenol, 2,3,4-, 2,4,6-Trichlorophenol, 2,3,4,5-, 2,3,4,6- and/or 2,3,5,6-Tetrachlorophenol and Pentachlorophenol could be identified as metabolites of Lindane. A degradation scheme is proposed. It includes gamma-Pentachlorocyclohexene, Hexachlorocyclohexene, Pentachlorocyclohexenol, Tetrachlorocyclohexenol and Polychlorophenols as main metabolites. The pathway based on many earlier published experimental results of these and other authors so far as possible.In former papers we have already reported about the known literature concerning the metabolism of Lindane (1 – 4).Comprehensive studies about the metabolism of Lindane in cultures of mould (1, 5, 6), in rats (7 – 9), and in men (2, 3) are to contribute in explaining away any uncertainties about the degradation of Lindane. Many investigations contributed to work out degradation schemes of Lindane (10 – 21).     

Dioxine in Lagerstätten-Tonen

In dominantly kaolinite-type, natural clay minerals, we found PCDDs at considerable levels (TEQ-values up to several hundred ng/kg). Contrary to expectations, PCDFs were not detected at all. The PCDD-contamination is most likely “natural” and not of anthropogenic origin.     

Impact of cannibalism on predator-prey dynamics: size-structured interactions and apparent mutualism

Direct and indirect interactions between two prey species can strongly alter the dynamics of predator-prey systems. Most predators are cannibalistic, and as a consequence, even systems with only one predator and one prey include two prey types: conspecifics and heterospecifics. The effects of the complex direct and indirect interactions that emerge in such cannibalistic systems are still poorly understood. This study examined how the indirect interaction between conspecific and heterospecific prey affects cannibalism and predation rates and how the direct interactions between both species indirectly alter the effect of the cannibalistic predator. I tested for these effects using larvae of the stream salamanders Eurycea cirrigera (prey) and Pseudotriton ruber (cannibalistic predator) by manipulating the relative densities of the conspecific and heterospecific prey in the presence and absence of the predator in experimental streams. The rates of cannibalism and heterospecific predation were proportional to the respective densities and negatively correlated, indicating a positive indirect interaction between conspecific and heterospecific prey, similar to "apparent mutualism." Direct interactions between prey species did not alter the effect of the predator. Although both types of prey showed a similar 30% reduction in night activity and switch in microhabitat use in response to the presence of the predator, cannibalism rates were three times higher than heterospecific predation rates irrespective of the relative densities of the two types of prey. Cumulative predation risks differed even more due to the 48% lower growth rate of conspecific prey. Detailed laboratory experiments suggest that the 3:1 difference in cannibalism and predation rate was due to the higher efficiency of heterospecific prey in escaping immediate attacks. However, no difference was observed when the predator was a closely related salamander species, Gyrinophilus porphyriticus, indicating that this difference is species specific. This demonstrates that cannibalism can result in the coupling of predator and prey mortality rates that strongly determines the dynamics of predator-prey systems.     

Framing environmental indicators: moving from causal chains to causal networks

In recent years, there has been a boom in environmental assessment reports utilizing environmental indicators. Most of these publications are based on the casual chain frameworks (e.g., Pressure–State–Response (PSR), Driving force–State–Response (DSR), and Driving force–Pressure–State–Impact–Response (DPSIR)). These frameworks have made an important contribution by emphasising the importance of causality. However, the reliance on simple uni-directional chains is at the same time not very conducive to a good understanding of the complexity of the processes behind environmental indicators. This limits the usefulness of these frameworks for environmental (impact) assessments. In this paper we propose an enhanced DPSIR (eDPSIR) framework for environmental indicators that takes inter-relations of indicators into account by relying on the use of causal networks rather than causal chains. It will be shown how the concept of causal networks can increase insight into the inter-relation of environmental issues and associated indicators, can facilitate the identification of key indicators for particular kinds of questions, and can provide a useful first step to the establishment of dose–response functions. Working with causal networks can contribute to more appropriate environmental policies and better management decisions.