Coupling a Detailed Transport Model to the Integrated Assessment Model REMIND

Environmental Modeling & Assessment - The transport sector is a crucial bottleneck in the decarbonization challenge. To study the sector’s decarbonization potential in the wider systems...     

When rate maximization is impulsive

Although optimal foraging theory predicts that natural selection should favor animal behaviors that maximize long-term rate of gain, behaviors observed in the laboratory tend to be impulsive. In binary-choice experiments, despite the long-term gain of each alternative, animals favor short handling times. Most explanations of this behavior suggest that there is hidden rationality in impulsiveness. Instead, we suggest that simultaneous and mutually exclusive binary-choice encounters are often unnatural and thus immune to the effects of natural selection. Using a simulation of an imperfect forager, we show how a simple strategy (i.e., an intuitive model of animal behavior) that maximizes long-term rate of gain under natural conditions appears to be impulsive under operant laboratory conditions. We then show how the accuracy of this model can be verified in the laboratory by biasing subjects with a short pre-experiment ad libitum high-quality feeding period. We also show a similar behavioral mechanism results in diet preferences that are qualitatively consistent with the digestive rate model of foraging (i.e., foraging under digestive rate constraints).     

Water quality requirements for sustaining aquifer storage and recovery operations in a low permeability fractured rock aquifer

A changing climate and increasing urbanisation has driven interest in the use of aquifer storage and recovery (ASR) schemes as an environmental management tool to supplement conventional water resources. This study focuses on ASR with stormwater in a low permeability fractured rock aquifer and the selection of water treatment methods to prevent well clogging. In this study two different injection and recovery phases were trialed. In the first phase ~1380 m(3) of potable water was injected and recovered over four cycles. In the second phase ~3300 m(3) of treated stormwater was injected and ~2410 m(3) were subsequently recovered over three cycles. Due to the success of the potable water injection cycles, its water quality was used to set pre-treatment targets for harvested urban stormwater of ≤ 0.6 NTU turbidity, ≤ 1.7 mg/L dissolved organic carbon and ≤ 0.2 mg/L biodegradable dissolved organic carbon. A range of potential ASR pre-treatment options were subsequently evaluated resulting in the adoption of an ultrafiltration/granular activated carbon system to remove suspended solids and nutrients which cause physical and biological clogging. ASR cycle testing with potable water and treated stormwater demonstrated that urban stormwater containing variable turbidity (mean 5.5 NTU) and organic carbon (mean 8.3 mg/L) concentrations before treatment could be injected into a low transmissivity fractured rock aquifer and recovered for irrigation supplies. A small decline in permeability of the formation in the vicinity of the injection well was apparent even with high quality water that met turbidity and DOC but could not consistently achieve the BDOC criteria.     

A framework for evaluating biodiversity mitigation metrics

Biodiversity mitigation is a cornerstone of applied conservation. Mitigation encompasses a suite of practices, ranging from planned avoidance of impacts to creation of new natural habitats. Accurate and appropriate metrics quantifying impacts to natural systems and the effectiveness of restoration are necessary to measure the success of different mitigation strategies. Because effective mitigation requires adequate metrics, we developed a Biodiversity Metrics Framework to assist practitioners and policy makers in assessing biodiversity mitigation metrics. Based on Noss’ Hierarchy of Biodiversity, the Scorecard highlights the mismatch between scientifically defined best practices and metrics required by policy. The Framework may serve a vital role in standardizing and validating mitigation projects into the future.

     

BUFFER STRIPS TO PROTECT WATER SUPPLY RESERVOIRS: A MODEL AND RECOMMENDATIONS1

ABSTRACT: Buffer strips are undisturbed, naturally vegetated zones around water supply reservoirs and their tributaries that are a recognized and integral aspect of watershed management. These strips can be very effective in protecting the quality of public potable water supply reservoirs by removing sediment and associated pollutants, reducing bank erosion, and displacing activities from the water's edge that represent potential sources of nonpoint source pollutant generation. As part of a comprehensive watershed management protect for the State of New Jersey, a parameter-based buffer strip model was developed for application to all watersheds above water supply intakes or reservoirs. Input requirements for the model include a combination of slope, width, and time of travel. The application of the model to a watershed in New Jersey with a recommended buffer strip width that ranges from 50 to 300 feet, depending upon a number of assumptions, results in from 6 to 13 percent of the watershed above the reservoir being occupied by the buffer.     

Levels of behavioral organization and the evolution of division of labor

The major features of insect societies that fascinate biologists are the self-sacrificing altruism expressed by colony members, the complex division of labor, and the tremendous plasticity demonstrated in the face of changing environments. The social behavior of insects is a result of complex interactions at different levels of biological organization. Genes give rise to proteins and peptides that build the nervous and muscular systems, regulate their own synthesis, interact with each other, and affect the behavior of individuals. Social behavior emerges from the complex interactions of individuals that are themselves far removed from the direct effects of the genes. In order to understand how social organization evolves, we must understand the mechanisms that link the different levels of organization. In this review, we discuss how behavior is influenced by genes and the neural system and how social behavior emerges from the behavioral activities of individuals. We show how different levels of organization share common features and are linked through common mechanisms. We focus on the behavior of the honey bee, the best studied of all social insects.     

Resource Depletion and Sustainability in Small Open Economies

Exogenous price changes affect the amount that a small country exporting natural resource commodities must invest to sustain its consumption level. The necessary amount is given by the difference between Hotelling rent and the discounted sum of future terms-of-trade effects (capital gains). The latter term is found to be large relative to the former in the case of petroleum depletion in Indonesia. This suggests that resource-rich countries will need to invest more than previously expected to sustain their consumption levels, if natural resource prices continue their long-term historical decline.     

Effects of worker genotypic diversity on honey bee colony development and behavior (Apis mellifera L.)

There have been numerous reports of genetic influences on division of labor in honey bee colonies, but the effects of worker genotypic diversity on colony behavior are unclear. We analyzed the effects of worker genotypic diversity on the phenotypes of honey bee colonies during a critical phase of colony development, the nest initiation phase. Five groups of colonies were studied (n = 5–11 per group); four groups had relatively low genotypic diversity compared to the fifth group. Colonies were derived from queens that were instrumentally inseminated with the semen of four different drones according to one of the following mating schemes: group A, 4 A-source drones; group B, 4 B-source drones; group C, 4 C-source drones; group D, 4 D-source drones; and group E, 1 drone of each of the A-D drone sources. There were significant differences between colonies in groups A-D for 8 out of 19 colony traits. Because the queens in all of these colonies were super sisters, the observed differences between groups were primarily a consequence of differences in worker genotypes. There were very few differences (2 out of 19 traits) between colonies with high worker genotypic diversity (group E) and those with low diversity (groups A-D combined). This is because colonies with greater diversity tended to have phenotypes that were average relative to colonies with low genotypic diversity. We hypothesize that the averaging effect of genotypic variability on colony phenotypes may have selective advantages, making colonies less likely to fail because of inappropriate colony responses to changing environmental conditions.     

Effects of interactions among genotypically diverse nestmates on task specialization by foraging honey bees (Apis mellifera)

Summary Recent studies have shown that differences in patterns of task specialization among nestmate honeybee workers (Apis mellifera) can be explained, in part, as a consequence of genotypic variability. Here, we present evidence supporting the hypothesis that an individual's pattern of task specialization is affected not only by her own genotype, but, indirectly, by the genotypes of her nestmates. Workers from two strains of honey bees, one selected for high pollen hoarding, the other for low pollen hoarding, were observed in colonies of their respective parent strains and in colonies of the other strain. Worker genotype and host-colony type affected foraging activity. Workers from the high strain fostered in low-strain colonies returned with pollen on 75.6% of total foraging trips, while workers from the high strain fostered in high-strain colonies returned with pollen on 53.5% of total trips. Workers from the low strain fostered in low-strain colonies returned with pollen on 34.8% of total foraging trips while workers from the low strain fostered in high-strain colonies returned with pollen on 2.6% of total trips. Similar results were obtained in a second experiment. We suggest that workers influence the behavior of their nestmates indirectly through their effects on the shared colony environment. The asymmetry seen in the response of workers from these strains to the two types of colony environments also suggests that these genotypes exhibit different norms of reaction. Offprint requests to: N.W. Calderone