The association between rural–urban migration flows and urban air quality in China

In light of the rapid urbanization of the world’s population over the past decades, there is a growing concern about the environmental impacts of urban population growth. Rural–urban migration is a particularly important component of the urbanization process in developing countries and is often considered to be detrimental to urban environmental conditions. However, few studies have explicitly examined the presumed negative impacts of in-migration on the natural environment of cities. The continuously increasing volume of rural–urban labor migration in China since the early 1980s has formed the largest population flow in world history. This study links the existing literature on population–environment and urbanization–environment interactions by empirically assessing the relationship between rural–urban migration and urban air conditions in China. A two-period (2004 and 2010) longitudinal dataset for the 113 key environmental protection cities of China was constructed based on multiple data sources. We applied the STIRPAT equation using conventional and spatial panel regression models to examine whether rural–urban migration flows were associated with air pollution in cities. Results show a strong negative association of in-migration with urban air quality even after controlling for the effects of other population, affluence, and technology factors. Findings from this research can contribute to a better understanding of the environmental consequences of rural–urban migration in China, with broader implications for sustainable development research and policies.     

Connecting Marine Ecosystem Services to Human Well-being: Insights from Participatory Well-being Assessment in Kenya

The linkage between ecosystems and human well-being is a focus of the conceptualization of “ecosystem services” as promoted by the Millennium Ecosystem Assessment. However, the actual nature of connections between ecosystems and the well-being of individuals remains complex and poorly understood. We conducted a series of qualitative focus groups with five different stakeholder groups connected to a small-scale Kenyan coastal fishery to understand (1) how well-being is understood within the community, and what is important for well-being, (2) how people’s well-being has been affected by changes over the recent past, and (3) people’s hopes and aspirations for their future fishery. Our results show that people conceive well-being in a diversity of ways, but that these can clearly map onto the MA framework. In particular, our research unpacks the “freedoms and choices” element of the framework and argues for greater recognition of these aspects of well-being in fisheries management in Kenya through, for example, more participatory governance processes.     

Movements and depth/temperature distribution of the ectothermic Scombrid, Acanthocybium solandri (wahoo), in the western North Atlantic

Pop-up satellite archival tags were deployed onto four wahoo during 2006 in the western North Atlantic (~26.5°N, 79.3°W), providing movement, depth, and temperature data collected over a total of 198?days. Straight-line distances between tag deployment and pop-off positions ranged from 162.5 to 1,960.0?km. Wahoo spent >90?% of their time in water <200?m, and >90?% of their time in water between 17.5 and 27.5?°C. Three fish made regular trips to depths >200?m. All four fish had significantly different depth distributions between the dark and light periods (Kruskal–Wallace test, p?相似文献   

Behavioural switching in a central place forager: patterns of diving behaviour in the macaroni penguin (Eudyptes chrysolophus)

Recording the activity of animals as they migrate or forage has proven hugely advantageous to understanding how animals use their environment. Where animals cannot be directly observed, the problem remains of how to identify distinct behaviours that represent an animal’s decision-making process. An excellent example of this problem is that of foraging penguins, which travel to sea to find prey to provision their young. Without direct sampling of the prey field, we cannot calibrate patterns of movement with prey capture, and therefore we cannot determine how different activities link to decision-making. To overcome this, we use a hidden markov model (HMM), which is a machine-learning technique that seeks to identify the underlying states of a system from observable outputs. We apply HMM to determine classes of behaviour from repetitive dives. We take dive data from 103 breeding macaroni penguins at Bird Island, South Georgia, for which we have measures of weight gain over a trip. We identify two classes of behaviour; those of short-shallow and long-deep dives. Using these two behaviours, we calculate the transition probabilities between these states and analyse these data to determine what predicts variation in the transition probabilities. We found that the stage of reproduction during a season, the sex and year of an individual influenced the probability of transition between long-deep and short-shallow sequential dives. We also found differences in the hourly transition rates between the four reproductive stages (incubation, broodguard, crèche and premoult) over a daily cycle. We conclude that this application of HMMs for behavioural switching is potentially useful for other species and other types of recorded behaviour.     

Seasonal variation in ejaculate traits of male red-winged blackbirds (Agelaius phoeniceus)

Many reproductive traits, including ejaculate characteristics, usually show remarkable seasonal variation, but the potential for such dynamics in sperm morphology has been overlooked. Several studies have revealed high within-male repeatability in sperm morphology, but samples have typically been collected within a few hours or days, and the consistency of sperm morphology over longer periods remains unexplored. Here, we tested whether ejaculate traits, including sperm morphology, sperm number, and sperm velocity, exhibit seasonal phenotypic plasticity in a long-lived seasonal breeder, the red-winged blackbird (Agelaius phoeniceus). We found absolute and/or relative flagellum length and sperm velocity to increase across the season, whereas sperm numbers within ejaculates declined. Sperm morphological traits were further positively associated with harem size or the total number of offspring that fledged in each male’s territory, suggesting that sperm morphology is likely to be linked to male reproductive quality. The underlying mechanisms of these patterns of seasonal variation remain unresolved, but we discuss our results in the context of dynamics of reproductive hormones, testicular structures and function, and reproductive behavior.