Visualisation of the complexity of EUSES

The interdependencies of parameters applied in the models of EUSES are visualised in a directed connectivity graph. The parameters (inputs, defaults, state variables, outputs) are represented by boxes (nodes) and their relations by lines (edges). The visualisation, on the one hand, clarifies the complexity of the models in EUSES and, on the other hand, creates an overview and transparency. The parameters’ relations to each other can be recognised faster, and the models can be better understood. The complexity was quantified by the number (variety), kind (substance parameter, physico-chemical parameter, concentration, other parameters), and depth (dimension) of the parameter and the number of relations (connectivity). The variety of EUSES (without the modelsSimple Treat andSimple Box whose interior structure is not documented and without the effect and risk characterisation) amounts to 466, the connectivity to 961, and the maximal dimension is 21.     

European scenarios for EUSES regional distribution model

The regional multimedia distribution model incorporated into EUSES 1.0 is used for the estimation of regionally predicted environmental concentrations in different European scenarios: a scenario representing a typical region in the north of Europe (high fraction connected to sewer systems, lower environmental temperature, high fractions of surface water and natural soil and a low fraction for agricultural soil) and another scenario representing a typical region in the south of Europe (low fraction connected to sewer systems, higher environmental temperature, low fractions for surface water and natural soil, and a high fraction for agricultural soil). The two scenarios are based on average data of countries in Northern and Southern Europe, but are not realistic for any specific country located in these regions. Scenario calculations were carried out using these two scenarios in addition to the generic standard region, given in EUSES 1.0 as a default scenario, and the North-Rhine Westphalian region. The substance properties, including emissions, were left unchanged for all scenarios. For a number of substances, the calculated concentrations in both the North and the South of Europe turned out to be higher than those calculated with the standard generic scenario. Thus, the standard scenario cannot be considered as a 'worst case' scenario per se. Uncertainties due to the regional heterogeneity within Europe are high. It is recommended to use these two additional scenarios for an improved estimation of possible concentration ranges in Europe.     

Human influence on California fire regimes.

Periodic wildfire maintains the integrity and species composition of many ecosystems, including the mediterranean-climate shrublands of California. However, human activities alter natural fire regimes, which can lead to cascading ecological effects. Increased human ignitions at the wildland-urban interface (WUI) have recently gained attention, but fire activity and risk are typically estimated using only biophysical variables. Our goal was to determine how humans influence fire in California and to examine whether this influence was linear, by relating contemporary (2000) and historic (1960-2000) fire data to both human and biophysical variables. Data for the human variables included fine-resolution maps of the WUI produced using housing density and land cover data. Interface WUI, where development abuts wildland vegetation, was differentiated from intermix WUI, where development intermingles with wildland vegetation. Additional explanatory variables included distance to WUI, population density, road density, vegetation type, and ecoregion. All data were summarized at the county level and analyzed using bivariate and multiple regression methods. We found highly significant relationships between humans and fire on the contemporary landscape, and our models explained fire frequency (R2 = 0.72) better than area burned (R2 = 0.50). Population density, intermix WUI, and distance to WUI explained the most variability in fire frequency, suggesting that the spatial pattern of development may be an important variable to consider when estimating fire risk. We found nonlinear effects such that fire frequency and area burned were highest at intermediate levels of human activity, but declined beyond certain thresholds. Human activities also explained change in fire frequency and area burned (1960-2000), but our models had greater explanatory power during the years 1960-1980, when there was more dramatic change in fire frequency. Understanding wildfire as a function of the spatial arrangement of ignitions and fuels on the landscape, in addition to nonlinear relationships, will be important to fire managers and conservation planners because fire risk may be related to specific levels of housing density that can be accounted for in land use planning. With more fires occurring in close proximity to human infrastructure, there may also be devastating ecological impacts if development continues to grow farther into wildland vegetation.     

The interaction of cannibalism and omnivory: consequences for community dynamics

Although cannibalism is ubiquitous in food webs and frequent in systems where a predator and its prey also share a common resource (intraguild predation, IGP), its impacts on species interactions and the dynamics and structure of communities are still poorly understood. In addition, the few existing studies on cannibalism have generally focused on cannibalism in the top-predator, ignoring that it is frequent at intermediate trophic levels. A set of structured models shows that cannibalism can completely alter the dynamics and structure of three-species IGP systems depending on the trophic position where cannibalism occurs. Contrary to the expectations of simple models, the IG predator can exploit the resources more efficiently when it is cannibalistic, enabling the predator to persist at lower resource densities than the IG prey. Cannibalism in the IG predator can also alter the effect of enrichment, preventing predator-mediated extinction of the IG prey at high productivities predicted by simple models. Cannibalism in the IG prey can reverse the effect of top-down cascades, leading to an increase in the resource with decreasing IG predator density. These predictions are consistent with current data. Overall, cannibalism promotes the coexistence of the IG predator and IG prey. These results indicate that including cannibalism in current models can overcome the discrepancy between theory and empirical data. Thus, we need to measure and account for cannibalistic interactions to reliably predict the structure and dynamics of communities.     

The Characterization of Ozone,Sulfur Dioxide,and Nitrogen Dioxide for Selected Monitoring Sites in the Federal Republic of Germany

Ambient ozone, sulfur dioxide, and nitrogen dioxide data collected at 11 rural gaseous air pollution monitoring stations located throughout the Federal Republic of Germany (FRG) were characterized to provide a basis for investigating the effect these air pollutants may have on forest decline. For any given year, with the exception of the Waldhof site, the ozone monitoring sites did not experience more than 50 occurrences of hourly mean concentrations equal to or above 0.10 ppm. In most cases, the number of occurrences equal to or above 0.10 ppm at the FRG ozone monitoring sites was below the number experienced at a rural forested site located at Whiteface Mountain, New York. Several of the FRG monitoring sites experienced a large number of occurrences of hourly mean ozone concentrations between 0.08 and 0.10 ppm. Hof, Selb, Arzberg, and Waldhof experienced several occurrences of elevated levels of sulfur dioxide concentrations. The nitrogen dioxide 24-h mean concentrations were low for all sites. Because the 24-h mean data may mask the occurrence of a few high concentration events, it is not known if any of the sites that monitored nitrogen dioxide experienced short-term elevated concentrations. To gain further insight into the possible effect of pollutant mixtures on vegetation, future efforts should involve characterizing the timing of multi-pollutant exposures.     

Aromatized arborane/fernane hydrocarbons as biomarkers for cordaites

Previous palaeobotanical and palynological studies on coals from Euramerican Pennsylvanian (≡ Late Carboniferous) coal basins indicate a major change in coal-swamp floras, especially at the Westphalian–Stephanian (≈Kasimovian–Gzhelian, according to Geological Time Scale 2004) boundary. A flora dominated by arborescent lycophytes was replaced by a vegetation dominated by marattialean tree ferns in various Euramerican coal basins. Earlier combined palynological and organic geochemical studies on Westphalian/Stephanian coals and shales from the Saar-Nahe Basin (Germany) revealed that the distribution of aromatized arborane/fernane hydrocarbons in solvent extracts reflects the increasing importance of seed plants, especially cordaites (extinct group of gymnosperms), conifers and pteridosperms. However, the biological source of the precursor molecules could not be specified. To clarify if the arborane/fernane derivatives MATH, MAPH, DAPH 1, and DAPH 2 in Westphalian/Stephanian coals can be assigned to one of the three potential source plant groups, we analyzed coals, sediments and fossil plant remains from different Euramerican locations with respect to their biomarker composition and stable carbon isotopic composition. Thereby, stable carbon isotopic ratios showed only insignificant variations between Westphalian and Stephanian samples and proved to be an unsuitable tool to describe floral changes during the Westphalian/Stephanian of the Saar-Nahe Basin. In contrast, we were able to show for the first time that MATH, MAPH, DAPH 1 and DAPH 2 are prominent constituents only in extracts of cordaitean macrofossils and can therefore be regarded as biomarkers for this group of gymnosperms.     

Framework for the environmental impact assessment of operational shipping

Shipping is an important source of pollution affecting both atmospheric and aquatic environments. To allow for efficient mitigation of environmental degradation, it is essential to know the extent of the impacts of shipping in relation to other sources of pollution. Here, we give a perspective on a holistic approach to studies of the environmental impacts of operational shipping through presentation of an assessment framework developed and applied on a case of shipping in the Baltic Sea. Through transfer of knowledge and concepts, previously used in assessments of air pollution, now applied to assessments of marine pollution and underwater noise, the horizon of understanding of shipping-related impacts is significantly improved. It identifies the main areas of environmental degradation caused by shipping and potential improvements through legislation and technological development. However, as the vast majority of contaminants discharged into the sea are not routinely monitored and assessed, the links between pressure of contaminants from shipping and environmental state and impacts will not be caught in the current environmental regulatory frameworks.     

Cadmium binding by fractions of dissolved organic matter and humic substances from municipal solid waste compost

The agricultural practice of amending soils with composted municipal solid waste (MSW) adds significant amounts of organic matter and trace metals, including Cd. Under these conditions, soluble organic complexes of Cd formed in the compost may be more significant than previously thought, due to Cd bioavailability and mobility in the soil environment. To study the relative importance of different types of organic ligands in MSW compost for the binding of Cd, six fractions of the dissolved organic matter (DOM) in addition to humic acid (HA) and fulvic acid (FA) were extracted and their complexation of Cd quantified at pH 7 using an ion-selective electrode (ISE). The highest complexing capacities (CC) for Cd were found for the most humified ligands: HA (2386 micromol Cd g(-1) C of ligand), predialyzed FA (2468 micromol Cd g(-1) C), and HoA, a fulvic-type, easily soluble fraction (1042 micromol Cd g(-1) C). The differences in CC for Cd of the various organic ligands were not directly related to total acid-titratable or carboxylic groups, indicating the importance of sterical issues and other functional groups. The strength of association between Cd and the organic ligands was characterized by calculating stability constants for binding at the strongest sites (pK(int)) and modeling the distribution of binding site strengths. The pK(int) values of the DOM fractions ranged between 6.93 (HiN: polysaccharides) and 8.11 (HiB: proteins and aminosugars), compared with 10.05 for HA and 7.98 for FA. Hence, the highly complex and only partially soluble organic molecules from compost such as HA and FA demonstrated the highest capacity to sequester Cd. However, strong Cd binding of organic ligands containing N-functional groups (HiB) in addition to a high CC of soluble, humified ligands like HoA indicated the relevance of these fractions for the organic complexation of Cd in solution.     

Performance level and efficiency of two differing predator-avoidance strategies depend on nutritional state of the prey fish

Animal prey has developed a variety of behavioural strategies to avoid predation. Many fish species form shoals in the open water or seek refuge in structurally complex habitats. Since anti-predator strategies bear costs and are energy-demanding, we hypothesised that the nutritional state of prey should modify the performance level and efficiency of such strategies. In aquaria either containing or lacking a structured refuge habitat, well-fed or food-deprived juvenile roach (Rutilus rutilus) were exposed to an open-water predator (pikeperch, Sander lucioperca). Controls were run without predators. In the presence of the predator, roach enhanced the performance of the anti-predator strategy and increased the use of the refuge habitat whereby food-deprived roach were encountered more often in the structure than well-fed roach. Nonetheless more starved than well-fed roach were fed upon by the predator. In the treatments offering only open-water areas, roach always formed dense shoals in the presence of the predator. The shoal density, however, was lower in starved roach. Starving fish in shoals experienced the highest predation mortality across all experimental treatments. The experiment confirmed the plasticity of the anti-predator behaviour in roach and demonstrated that food deprivation diminished the efficiency of shoaling more strongly than the efficiency of hiding. The findings may be relevant to spatial distribution of prey and predator–prey interactions under natural conditions because when prey are confronted with phases of reduced resource availability, flexible anti-predator strategies may lead to dynamic habitat use patterns.