Influence of fish on habitat choice of water birds: a whole system experiment

It is notoriously difficult to study population interactions among highly mobile animals that cannot be meaningfully confined to experimental plots of limited size. For example, migratory water birds are believed to suffer from competition with resident fish populations for shared food resources. While observational evidence in support of this hypothesis is accumulating, replicated experiments addressing this issue at the proper spatial scale are lacking. Here, we report from a replicated whole-system experiment in which we stocked large (0.07 km2), shallow (< or =2.5 m deep), highly eutrophic ponds in the bird protection area "Ismaninger Speichersee mit Fischteichen" with different densities of carp and assessed the responses of water birds and their food resources during summer over several years. In all years, the biomasses of benthic macroinvertebrates, macroalgae, and macrophytes as well as the densities of herbivorous, carnivorous, and omnivorous water birds were reduced in carp ponds compared to fishless ponds. The negative effects of carp on food resources and on the numbers of water birds feeding in carp ponds increased over the season (May-September) and were stronger at high than at low stocking densities of carp. Consequently, differences in resource densities between ponds with and without carp increased, and the ranking of ponds with respect to resource densities became more predictable over the season. These factors may have contributed to a seasonal improvement of the birds' abilities to track resource densities across ponds, as suggested by tight correlations of bird numbers on ponds with resource densities late, but not early, in the season.     

A Bayesian approach for understanding the role of ship speed in whale-ship encounters

Mandatory or voluntary reductions in ship speed are a common management strategy for reducing deleterious encounters between large ships and large whales. This has produced strong resistance from shipping and marine transportation entities, in part because very few studies have empirically demonstrated whether or to what degree ship speed influences ship-whale encounters. Here we present the results of four years of humpback whale sightings made by observers aboard cruise ships in Alaska, representing 380 cruises and 891 ship-whale encounters. Encounters occurred at distances from 21 m to 1000 m (x = 567 m) with 61 encounters (7%) occurring between 200 m and 100 m, and 19 encounters (2%) within 100 m. Encounters were spatially aggregated and highly variable across all ship speeds. Nevertheless a Bayesian change-point model found that the relationship between whale distance and ship speed changed at 11.8 knots (6.1 m/s) with whales encountering ships, on average, 114 m closer when ship speeds were above 11.8 knots. Binning encounter distances by 1-knot speed increments revealed a clear decrease in encounter distance with increasing ship speed over the range of 7-17 knots (3.6-8.7 m/s). Our results are the first to demonstrate that speed influences the encounter distance between large ships and large whales. Assuming that the closer ships come to whales the more likely they are to be struck, our results suggest that reduced ship speed may be an effective management action in reducing the probability of a collision.     

The deep city: cultural heritage as a resource for sustainable local transformation

ABSTRACT

The sustainable city of the future is typically envisioned as smart, creative and disruptive, assuming that urban and local sustainability is achieved through new technology and innovation. However, considering that the built environments of our cities and surroundings are highly durable, there is also a need to focus on how resources brought from the past – histories, artefacts and places – may be used for promoting urban sustainability. We label this a “deep city” perspective on urban and local transformation. By looking at Røros, a World Heritage Site in central Norway with a dense and historic wooden urban centre, we investigate how its heritage protection facilitates the maintenance of a compact urban centre. We hold that a shared sense of place – the deepness– may serve as a resource against unsustainable sprawl and mall-oriented development.     

Climate Change in Southern and Eastern Africa During the Past Millennium and its Implications for Societal Development

Climatic records from equatorial eastern Africa and subtropical southern Africa have shown that both temperature and the amount of rainfall have varied over the past millennium. Moreover, the rainfall pattern in these regions varied inversely over long periods of time. Droughts started abruptly, were of multi-decadal to multi-centennial length and the changes in the hydrological budget were of large amplitude. Changing water resources in semi-arid regions clearly must have regional influences on both ecological and socio-economic processes. Through a detailed analysis of the historical and paleoclimatic evidence from southern and eastern Africa covering the past millennium it is shown that, depending on the vulnerability of a society, climatic variability can have an immense impact on societies, sometimes positive and sometimes disastrous. Therefore, the interconnected issue of world ecosystem and social resilience is the challenge for decision-makers if sustainable development is to be reached on global and local levels.     

Unintentional injuries among infants age 0-12 months

Each year an estimated 328,500 infants age 0-12 months are treated for unintentional injuries in emergency departments (EDs): one infant every minute and a half. The leading cause, overall and by month of age, was fall-related injury. The second leading cause was 'struck by or against.' The majority of patients were injured at home. Younger infants were more likely to be hospitalized than older ones and more males than females were injured. Gender differences suggest that parenting practices may play a role, but ecological approaches should be considered in an effort to understand the connection between injuries and an infant's developmental stage.     

发展一种估算石油工业温室气体排放的一致的方法

要获得有意义的温室气体清单,重要的是清单中包括的内容的方法论和定义应该是一致的.国际石油工业环境保护协会(IPIECA)、国际石油和天然气生产者协会(OGP)以及美国石油学会(API)已经制定了温室气体排放计算和报告的准则.国际石油工业环境保护协会(IPITCA)报告温室气体排放的石油工业指南的重点是放在石油工业温室气体排放的计算和报告上.为了提供排放估算一致的方法论,美国石油工业协会制定了石油和天然气工业温室气体排放估算方法论概要.从美国石油学会可以得到一个估算排放的工具--SANGEATM能源和排放估算系统.     

Wildfire, landscape diversity and the Drossel-Schwabl model

How simple can a model be that still captures essential aspects of wildfire ecosystems at large spatial and temporal scales? The Drossel-Schwabl model (DSM) is a metaphorical forest-fire model developed to reproduce only one pattern of real systems: a frequency distribution of fire sizes resembling a power law. Consequently, and because it appears oversimplified, it remains unclear what bearings the DSM has in reality. Here, we test whether the DSM is capable of reproducing a pattern that was not considered in its design, the hump-shaped relation between the diversity of succession stages and average annual area burnt. We found that the model, once reformulated to represent succession, produces realistic landscape diversity patterns. We investigated four succession scenarios of forest-fire ecosystems in the USA and Canada. In all scenarios, landscape diversity is highest at an intermediate average annual area burnt as predicted by the intermediate disturbance hypothesis. These results show that a model based solely on the dynamics of the fuel mosaic has surprisingly high predictive power with regard to observed statistical properties of wildfire systems at large spatial scales. Parsimonious models, such as the DSM can be used as starting points for systematic development of more structurally realistic but tractable wildfire models. Due to their simplicity they allow analytical approaches that further our understanding under increasing complexity.     

Managing Swedish forestry’s impact on mercury in fish: Defining the impact and mitigation measures

Inputs of anthropogenic mercury (Hg) to the environment have led to accumulation of Hg in terrestrial and aquatic ecosystems, contributing to fish Hg concentrations well above the European Union standards in large parts of Fennoscandia. Forestry operations have been reported to increase the concentrations and loads of Hg to surface waters by mobilizing Hg from the soil. This summary of available forestry effect studies reveals considerable variation in treatment effects on total Hg (THg) and methylmercury (MeHg) at different sites, varying from no effect up to manifold concentration increases, especially for the bioavailable MeHg fraction. Since Hg biomagnification depends on trophic structures, forestry impacts on nutrient flows will also influence the Hg in fish. From this, we conclude that recommendations for best management practices in Swedish forestry operations are appropriate from the perspective of mercury contamination. However, the complexity of defining effective policies needs to be recognized.