Disentangling the effects of group size and density on shoaling decisions of three-spined sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>)

Many animals live in groups most of their life. One function of this behaviour is an increased predator protection whereas larger groups provide better protection than smaller ones. A causal explanation is that due to a higher number of shoal members the individual risk of being predated will decrease (“dilution effect”). Additionally, shoaling leads to increased predator confusion. This “confusion effect” can be strengthened by an increased group density, which often correlates with group size. Many studies found that individuals prefer the larger of two groups. However, whether this preference is due to a larger group size or because of an increased density of the larger group remained unclear. To disentangle these factors we gave three-spined sticklebacks (Gasterosteus aculeatus) the choice between shoals of (1) different group size and density, (2) different group size, but equal density and (3) equal group sizes, but different densities. As expected, test fish preferred the larger and denser shoal over the smaller, less dense one. This preference was lost when shoal size differed but density was kept constant. When shoal size was equal but density differed, test fish preferred the less dense shoal. However, this was only the case when test fish chose between two relatively dense shoals. On the other hand, when overall density was low, test fish did not discriminate between shoals of different densities. This result may be explained in terms of predator avoidance. The results show that shoaling preferences might not always be influenced by a higher number of group members but also by the density and cohesiveness of the respective groups. An erratum to this article can be found at     

Bakterielle Biotestverfahren zur Bestimmung der Toxizität von Abfällen

For a risk assessment of wastes, fast and sensitive screening methods are required to detect possible toxic effects. In this study, different leachability methods (DIN 38414, part 4; EPA 1310; EPA 1320) were used to prepare aqueous leachates from different wastes; these leachates were rested in different bacterial toxicity test systems for possible toxic effects. As bacterial toxicity tests, the luminescent bacteria test and the growth inhibition test with activated sludge bacteria were used. The test systems showed a good agreement of the results from the different leaching methods, thereby indicating the reliability of the test systems used. The luminescent bacteria inhibition test showed a higher sensitivity than the growth inhibition test which is in good accordance with literature data. We conclude that both test systems are well suited to assess the toxic potential of aqueous waste leachates.     

Pesticide transport pathways from a sloped Litchi orchard to an adjacent tropical stream as identified by hydrograph separation

This study was performed to identify the transport pathways of pesticides from a sloped litchi ( Sonn.) orchard to a nearby stream based on a three-component hydrograph separation (baseflow, interflow, surface runoff). Dissolved silica and electrical conductivity were chosen as representative tracers. During the study period (30 d), 0.4 and 0.01% of the applied mass of atrazine and chlorpyrifos, respectively, were detected in the stream after 151 mm of rainfall. Baseflow (80-96%) was the dominant hydrological flow component, followed by interflow (3-18%) and surface runoff (1-7%). Despite its small contribution to total discharge, surface runoff was the dominant atrazine transport pathway during the first days after application because pesticide concentrations in the surface runoff flow component declined quickly within several days. Preferential transport with interflow became the dominant pathway of atrazine. Because chlorpyrifos was detected in the stream water only twice, it was not included in the hydrograph separation. A feature of the surface runoff pathway was the coincidence of pesticide and discharge peaks. In contrast, peak concentrations of pesticides transported by interflow occurred during the hydrograph recession phases. Stormflow generation and pesticide transport depended on antecedent rainfall. The combination of high-resolution pesticide concentration measurements with a three-component hydrograph separation has been shown to be a suitable method to identify pesticide transport pathways under tropical conditions.     

Transdisciplinary research in support of land and water management in China and Southeast Asia: evaluation of four research projects

Transdisciplinary research (TDR) aims at identifying implementable solutions to difficult sustainability problems and at fostering social learning. It requires a well-managed collaboration among multidisciplinary scientists and multisectoral stakeholders. Performing TDR is challenging, particularly for foreign researchers working in countries with different institutional and socio-cultural conditions. There is a need to synthesize and share experience among researchers as well as practitioners regarding how TDR can be conducted under specific contexts. In this paper, we aim to evaluate and synthesize our unique experience in conducting TDR projects in Asia. We applied guiding principles of TDR to conduct a formative evaluation of four consortium projects on sustainable land and water management in China, the Philippines, and Vietnam. In all projects, local political conditions restricted the set of stakeholders that could be involved in the research processes. The set of involved stakeholders was also affected by the fact that stakeholders in most cases only participate if they belong to the personal network of the project leaders. Language barriers hampered effective communication between foreign researchers and stakeholders in all projects and thus knowledge integration. The TDR approach and its specific methods were adapted to respond to the specific cultural, social, and political conditions in the research areas, also with the aim to promote trust and interest of the stakeholders throughout the project. Additionally, various measures were implemented to promote collaboration among disciplinary scientists. Based on lessons learned, we provide specific recommendations for the design and implementation of TDR projects in particular in Asia.     

Alveolar Breath Sampling and Analysis to Assess Exposures to Methyl Tertiary Butyl Ether (MTBE) During Motor Vehicle Refueling

Abstract

Methyl tertiary butyl ether (MTBE) is added to gasoline (15% by volume) in many areas of the U.S. to help control carbon monoxide emissions from motor vehicles. In this study we present a sampling and analytical methodology that can be used to assess consumers' exposures to MTBE that may result from routine vehicle refueling operations. The method is based on the collection of alveolar breath samples using evacuated one-liter stainless steel canisters and analysis using a gas chromatograph-mass spectrometer equipped with a patented "valveless" cryogenic preconcentrator.

To demonstrate the utility of this approach, a series of breath samples was collected from two individuals (the person pumping the fuel and a nearby observer) immediately before and for 64 min after a vehicle was refueled with premium grade gasoline. Results demonstrate low levels of MTBE in both subjects' breaths before refueling, and levels that increased by a factor of 35 to 100 after the exposure. Breath elimination models fitted to the post exposure measurements indicate that the half-life of MTBE in the first physiological compartment was between 1.3 and 2.9 min. Analysis of the resulting models suggests that breath elimination of MTBE during the 64 min monitoring period was approximately 115 jug for the refueling subject while it was only 30 ug for the nearby observer. This analysis also shows that the post exposure breath elimination of other gasoline constituents was consistent with previously published observations.

These results demonstrate that this new methodology can be used effectively in studies designed to assess exposures to MTBE. The method can be used to objectively demonstrate recent exposures, the relative magnitude of an exposure, and the approximate duration of the resulting bloodborne dose. Once a blood/breath partition coefficient for MTBE has been firmly established, the bloodborne concentration of the absorbed material can be determined using these techniques as well.     

Coordination through databases can improve prescribed burning as a conservation tool to promote forest biodiversity

Prescribed fires are a common nature conservation practice. They are executed by several parties with limited coordination among them, and little consideration for wildfire occurrences and habitat requirements of fire-dependent species. Here, we gathered data on prescribed fires and wildfires in Sweden during 2011–2015 to (i) evaluate the importance and spatial extent of prescribed fires compared to wildfires and (ii) illustrate how a database can be used as a management tool for prescribed fires. We found that on average only 0.006% (prescribed 65%, wildfires 35%) of the Swedish forest burns per year, with 58% of the prescribed fires occurring on clearcuts. Also, both wildfires and prescribed fires seem to be important for the survival of fire-dependent species. A national fire database would simplify coordination and make planning and evaluation of prescribed fires more efficient. We propose an adaptive management strategy to improve the outcome of prescribed fires.     

Mapping social–ecological vulnerability to inform local decision making

An overarching challenge of natural resource management and biodiversity conservation is that relationships between people and nature are difficult to integrate into tools that can effectively guide decision making. Social–ecological vulnerability offers a valuable framework for identifying and understanding important social–ecological linkages, and the implications of dependencies and other feedback loops in the system. Unfortunately, its implementation at local scales has hitherto been limited due at least in part to the lack of operational tools for spatial representation of social–ecological vulnerability. We developed a method to map social–ecological vulnerability based on information on human–nature dependencies and ecosystem services at local scales. We applied our method to the small‐scale fishery of Moorea, French Polynesia, by combining spatially explicit indicators of exposure, sensitivity, and adaptive capacity of both the resource (i.e., vulnerability of reef fish assemblages to fishing) and resource users (i.e., vulnerability of fishing households to the loss of fishing opportunity). Our results revealed that both social and ecological vulnerabilities varied considerably through space and highlighted areas where sources of vulnerability were high for both social and ecological subsystems (i.e., social–ecological vulnerability hotspots) and thus of high priority for management intervention. Our approach can be used to inform decisions about where biodiversity conservation strategies are likely to be more effective and how social impacts from policy decisions can be minimized. It provides a new perspective on human–nature linkages that can help guide sustainability management at local scales; delivers insights distinct from those provided by emphasis on a single vulnerability component (e.g., exposure); and demonstrates the feasibility and value of operationalizing the social–ecological vulnerability framework for policy, planning, and participatory management decisions.     

Water column use and forage strategies of female southern elephant seals from Marion Island

The at-sea behaviour of marine top predators provides valuable insights into the distribution of prey species and strategies used by predators to exploit patchily distributed resources. We describe the water column usage and dive strategies of female southern elephant seals from Marion Island tracked between 2004 and 2008. Dives representing increases in forage effort were identified using a method that combines dive type analyses and the calculation of relative amounts of time that animals spend in the bottom phases of dives. Results from this analysis indicate that female elephant seals from Marion Island tend to display lower levels of forage effort closer to the island and display intensive opportunistic forage bouts that occur at a minimum distance of approximately 215 km from the island. Females from Marion Island dived deeper and for longer periods of time, compared to females from other populations. Most animals displayed positive diel vertical migration, evidently foraging pelagically on vertically migrating prey. A few animals displayed periods of reverse (negative) diel vertical migration, however, diving to deeper depths at night, compared to daytime. This behaviour is difficult to explain and prey species targeted during such periods unknown. Our results illustrate plasticity in foraging behaviour of southern elephant seals, as well as inter-population differences in forage strategies.