Contagious cooperation,temptation, and ecosystem collapse

Real world observations suggest that social norms of cooperation can be effective in overcoming social dilemmas such as the joint management of a common pool resource—but also that they can be subject to slow erosion and sudden collapse. We show that these patterns of erosion and collapse emerge endogenously in a model of a closed community harvesting a renewable natural resource in which individual agents face the temptation to overexploit the resource, while a cooperative harvesting norm spreads through the community via interpersonal relations. We analyze under what circumstances small changes in key parameters (including the size of the community, and the rate of technological progress) trigger catastrophic transitions from relatively high levels of cooperation to widespread norm violation—causing the social–ecological system to collapse.     

Farm cooperation to improve sustainability

In this paper, it is demonstrated that partnership arrangements between farmers might be a way to secure the economic viability of their farms as well as to increase profitability. The article discusses empirical analyses of three different forms of collaboration, with an emphasis on the environmental improvements associated with collaboration. Collaboration between a dairy farm and a crop farm is analyzed in the first case. The results show that potential gains from improved diversification and crop rotation are substantial, and even larger when the collaboration also involves machinery. The second analysis considers external integration between farrowing and finishing-pig operations. Gains from collaboration originate from biological and technical factors, such as improved growth rate of the pigs and better utilization of buildings. Finally, an evaluation of a group of collaborating crop farmers is performed. In this case, the benefits that arise are mainly due to reduced machinery costs and/or gains due to other factors, such as improved crop rotation and managerial/marketing strategies.     

Effects of an invasive polychaete on benthic phosphorus cycling at sea basin scale: An ecosystem disservice

Macrofaunal activities in sediments modify nutrient fluxes in different ways including the expression of species-specific functional traits and density-dependent population processes. The invasive polychaete genus Marenzelleria was first observed in the Baltic Sea in the 1980s. It has caused changes in benthic processes and affected the functioning of ecosystem services such as nutrient regulation. The large-scale effects of these changes are not known. We estimated the current Marenzelleria spp. wet weight biomass in the Baltic Sea to be 60–87 kton (95% confidence interval). We assessed the potential impact of Marenzelleria spp. on phosphorus cycling using a spatially explicit model, comparing estimates of expected sediment to water phosphorus fluxes from a biophysical model to ecologically relevant experimental measurements of benthic phosphorus flux. The estimated yearly net increases (95% CI) in phosphorous flux due to Marenzelleria spp. were 4.2–6.1 kton based on the biophysical model and 6.3–9.1 kton based on experimental data. The current biomass densities of Marenzelleria spp. in the Baltic Sea enhance the phosphorus fluxes from sediment to water on a sea basin scale. Although high densities of Marenzelleria spp. can increase phosphorus retention locally, such biomass densities are uncommon. Thus, the major effect of Marenzelleria seems to be a large-scale net decrease in the self-cleaning capacity of the Baltic Sea that counteracts human efforts to mitigate eutrophication in the region.     

Correction to: Documenting lemming population change in the Arctic: Can we detect trends?

Ambio - In the original published article, some of the symbols in figure 1A were modified incorrectly during the typesetting and publication process. The correct version of the figure is provided...     

Statistical matching for conservation science

The awareness of the need for robust impact evaluations in conservation is growing and statistical matching techniques are increasingly being used to assess the impacts of conservation interventions. Used appropriately matching approaches are powerful tools, but they also pose potential pitfalls. We outlined important considerations and best practice when using matching in conservation science. We identified 3 steps in a matching analysis. First, develop a clear theory of change to inform selection of treatment and controls and that accounts for real-world complexities and potential spillover effects. Second, select the appropriate covariates and matching approach. Third, assess the quality of the matching by carrying out a series of checks. The second and third steps can be repeated and should be finalized before outcomes are explored. Future conservation impact evaluations could be improved by increased planning of evaluations alongside the intervention, better integration of qualitative methods, considering spillover effects at larger spatial scales, and more publication of preanalysis plans. Implementing these improvements will require more serious engagement of conservation scientists, practitioners, and funders to mainstream robust impact evaluations into conservation. We hope this article will improve the quality of evaluations and help direct future research to continue to improve the approaches on offer.     

Habitat complexity reduces the growth of aggressive and dominant brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) relative to subordinates

Animals often prefer areas containing physical structure, and population density often increases with structural complexity, presumably because physical complexity in habitats may offer protection from predators and aggressive competitors. Consequently, increased habitat complexity often results in reduced territory size, lower aggression levels and reduced resource monopolisation by dominants. If behavioural plasticity is limited at early life stages, increased habitat complexity may reduce the relative fitness of aggressive, dominant strategies. Here we tested this hypothesis in an experiment on newly emerged brown trout (Salmo trutta) fry. We show, for the first time, that increased habitat complexity reduces the fitness (i.e. growth rate) of aggressive dominant individuals in relation to subordinates, and that this relation is reversed in simple habitats. Variation in environmental complexity may thus induce fluctuating selective pressures, maintaining behavioural variation in natural populations and allowing subordinate and dominant strategies to coexist.     

History and Ethics of Keeping Pets: Comparison with Farm Animals

Perhaps the commonest reasons for the keeping of pets are companionship and as a conduit for affection. Pets are, therefore, being “used” for human ends in much the same way as laboratory or farm animals. So shouldn’t the same arguments apply to the use of pets as to those used in other ways? In accepting the “rights” of farm animals to fully express their natural behavior, one must also accept the “right” of pets to express their intrinsic natural behavior. Dogs kept in houses for most of the day are being kept in an unnatural environment. So are rabbits kept in hutches, and guinea-pigs or birds in cages. These conditions infringe the animals’ telos. Dogs are naturally pack animals, so is a dog in isolation being denied its telos? Other actions more deliberately infringe telos and autonomy. Enforced shampooing – or even exercise; hair-cutting of poodles; putting animals in clothes; and tail-docking. If de-beaking of chickens is considered wrong, then the same must be true for tail-docking of dogs. One should also question the ethics of specialist breeding – especially when that results in physiological disadvantages (boxers with breathing troubles). There would appear to be no advantage to the animals in having such health problems and when these are the direct result of the breeders’ desire for specific cosmetic traits, we should question the ethics of the practice at least as much as when animals are bred for specific agricultural traits.     

The Development of Animal Behavior: From Lorenz to Neural Nets

In the study of behavioral development both causal and functional approaches have been used, and they often overlap. The concept of ontogenetic adaptations suggests that each developmental phase involves unique adaptations to the environment of the developing animal. The functional concept of optimal outbreeding has led to further experimental evidence and theoretical models concerning the role of sexual imprinting in the evolutionary process of sexual selection. From a causal perspective it has been proposed that behavioral ontogeny involves the development of various kinds of perceptual, motor, and central mechanisms and the formation of connections among them. This framework has been tested for a number of complex behavior systems such as hunger and dustbathing. Imprinting is often seen as a model system for behavioral development in general. Recent advances in imprinting research have been the result of an interdisciplinary effort involving ethology, neuroscience, and experimental psychology, with a continual interplay between these approaches. The imprinting results are consistent with Lorenz' early intuitive suggestions and are also reflected in the architecture of recent neural net models.     

Data search and environmental hazard assessment for post-seveso chemicals

After the serious accident with a chemical industrial plant at Seveso (Italy) in 1976, the Commission of the European Communities has made a directive on major accidents, usually called the Post-Seveso Guideline. In its annex III, a list of 178 substances is given for which potentially dangerous volumes in case of an accident are defined on the basis of human health criteria. For the implementation of environmental criteria, information on toxicity to aquatic organisms, dilution, and physical behavior in water is needed. A literature search for relevant data on these 178 substances revealed aquatic toxicity data for 116 substances, but only for 87 substances sufficient data were available to make a hazard assessment. As an example, the River Rhine was used to calculate the critical quantities that, after a sudden discharge in the Swiss part, could cause damage at the Dutch part some 800 km downstream. In the absence of a common opinion on the criteria for being a major accident and a serious environmental hazard, the impact of different criteria quantities is discussed. If, for example, in the whole River Rhine a mortality of 5% of the aquatic species is chosen as the criterion for damage to the ecosystem, the critical quantities as mentioned in the EEC directive have to be lowered drastically for the majority of the substances. For 18 substances it could be shown that release of the mentioned quantities would be catastrophic for aquatic life in the whole river.     

Shopping studies for regional planning

This paper is based on a shopping study carried out by the Department of Geography, University of Utrecht, during 1983. It is concerned with retail planning research for larger regions and starts with a state of the art review of retail planning research in the Netherlands. The aim, in developing a new research strategy, was to reduce time and costs through using computer facilit es for both data handling and data collection. There is discussion of methodology and some outcomes to demonstrate the possibilities of the strategy.