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.     

Ablagerung toxischer Chemieabfälle im August 2006 in Abidjan, Republik Côte d’Ivoire: Versuch einer Rekonstruktion

Background

Globally, every year several hundred million tons of problematic, e.g. chemical, wastes are generated stemming to more than 90% from the 25 OECD countries. Due to their partly considerable toxicity special and often expensive measures are required for their disposal. According to the Secretary of the ‘Basel Convention on the Control of Transboundary Movements of Hazardous Waste and Their Disposal’ annually at least 8.5 million tons of wastes are transboundarily traded. Although the ‘Basel Convention’ has set up rules how to handle international waste streams, certain waste amounts are illegally transported from the OECD countries to developing countries — basically for reasons of expenses. Often an environmental safe treatment of toxic waste is not ensured or even not possible in the receiving countries. As set forth in a report of the European Network for the Implementation and Enforcement of Environmental Law (IMPEL) published in 2006, the illegal trade with toxic waste has steadily increased. 3000 shipping documents of 17 European seaports were examined and 258 cargo holds were inspected showing that 68 of 140 waste shippings were illegal. Preventing illegal transports of waste meets with various obstacles. Controlling measures require considerable personal, technical, and logistic resources that are not sufficiently available in each country concerned. Missing or ineffective administrative structures hamper fast actions to stop illegal waste disposal. Partly, the political will to take the necessary steps is lacking. An additional problem is the fact that waste that is obtained from the regular shipping business is not subject to the Basel Convention but to the ‘International Convention for the Prevention of Pollution from Ships’. The implementing statures are summarized in the document MARPOL 73/78; the International Maritime Organization (IMO) is responsible. Identifying the origin of waste and thus defining the responsibility occasionally raises difficulties. This background provides a basis to try to reconstruct the course of events concerning the disposal of chemical waste in Abidjan.

Methods

Several information sources were utilized to reconstruct the course of events at Abidjan in August 2006; e.g. public press, declarations of international governmental organizations, especially of the UN and of its subsidiary organizations, communiqués of the Secretary of the Basel Convention, and statements of several NGOs. Nevertheless a complete reconstruction of the incident is impossible, since a detailed and reliable historical report is not available. Furthermore the responsible politicians have not undertaken significant efforts to shed light upon the incident. Additionally relevant documents of the participating companies are not available to the public.

Conclusions

The analyzed incident makes obvious that the control mechanisms of the Basel Convention can be circumvented. It remains unclear who has to take the political responsibility for the death of 10 people and for the health defects of thousands of humans. Possible civil and criminal consequences are not foreseeable for the actors and company owners involved in the illegal waste dumping. The people of Abidijan are confronted with unresolved questions regarding the occurrence of chronic diseases and possible long-term effects of remaining waste portions.

Recommendations and Perspectives

The incident demonstrates that the control of the transboundary transport and disposal of hazardous waste needs to be enforced and legal grey areas should be eliminated. It should be a task of the OECD countries and of all other economically and technically developed countries and organizations to support the developing countries’ efforts to build up the personal, technical, and infrastructural capacities for an efficient control of waste imports.     

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.     

Voltammetric determination of the herbicide Bifenox in drinking and river water using a silver solid amalgam electrode

A new method for the determination of submicromolar and nanomolar concentrations of herbicide Bifenox using differential pulse voltammetry at a mercury meniscus modified silver solid amalgam electrode is described. This new type of working electrode is non-toxic, environmentally friendly, and compatible with principles of green analytical chemistry, and its surface can be easily electrochemically renewed in the case of passivation. The newly developed direct differential pulse voltammetric determination of Bifenox gives limit of determination 6.7·10^?7 and 6.9·10^?7?M in drinking and river water, respectively. Both the selectivity and the sensitivity can be further increased by preliminary separation and preconcentration using solid phase extraction. This combination enables to reach limit of determination 0.9?×?10^?9 and 1.5?×?10^?9?M for drinking and river water, respectively. Because of lower running and investment costs, this electroanalytical method can be used for large scale monitoring of possible water contamination with tested herbicide.     

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.