Generalists and specialists along a latitudinal transect: patterns of thermal adaptation in six species of damselflies

Tropical organisms colonizing temperate environments face reduced average temperatures and dramatic thermal fluctuations. Theoretical models postulate that thermal specialization should be favored either when little environmental variation is experienced within generations or when among-generation variation is small relative to within-generation variation. To test these predictions, we studied six temperate species of damselflies differing in latitudinal distribution. We developed a computer model simulating how organisms experience environmental variation (accounting for diapause and voltinism) and performed a laboratory experiment assaying thermal sensitivities of growth rates. The computer model showed opposing latitudinal trends in among- and within-generation thermal variability: within-generation thermal variability decreased toward higher latitudes, whereas relative levels of among-generation thermal variability peaked at midlatitudes (where a shift in voltinism occurred). The growth experiment showed that low-latitude species were more thermally generalized than mid- and high-latitude species, supporting the prediction that generalists are favored under high levels of within-generation variation. Northern species had steeper, near-exponential reaction norms suggestive of thermal specialization. However, they had strikingly high thermal optima and grew very slowly over most of the thermal range they are expected to experience in the field. This observation is at present difficult to explain. These results highlight the importance of considering interactions between life history and environmental variation when deriving expectations of thermal adaptation.     

Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics

The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped oaks (dynamic patches). We estimate the age at which trees become suitable patches for different species, which defines their niche breadth (number of suitable trees). We show that the colonization rates were generally low, but increased with increasing connectivity in accordance with metapopulation theory. The rates were related to species traits, and we show, for the first time, that they are higher for species with wide niches and small dispersal propagules than for species with narrow niches or large propagules. We also show frequent long-distance dispersal in epiphytes by quantifying the relative importance of local dispersal and background deposition of dispersal propagules. Local stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the rate of patch destruction (tree fall). These findings mean that epiphyte metapopulations may have slow colonization-extinction dynamics that are explained by connectivity, species traits, and patch dynamics.     

Exaggerated orientation scatter of nocturnal passerine migrants close to breeding grounds: comparisons between seasons and latitudes

Using tracking radars, we investigated the variability of flight directions of long-distance nocturnal passerine migrants across seasons (spring versus autumn migration) and sites at the southern (56° N) and northern (68° N) ends of the Scandinavian Peninsula (Lund versus Abisko). Whilst most migrants at Lund are on passage to and from breeding sites in Fennoscandia, the majority of the migrants at Abisko are close to their breeding sites, and migration at Abisko thus to a large degree reflects initial departure from breeding sites (autumn) or final approach to breeding destinations (spring). The radar data were used to test predictions about differences in orientation and wind drift effects between adult and juvenile birds (a large proportion of autumn migrants consists of juvenile birds on their first journey), between situations far away from or near the goals and between different phases of migration (initial departure, en route passage, final approach to goal). The concentrations (both total and within-night concentrations) of flight directions differed significantly between seasons as well as sites, with the highest concentration at Lund in spring (mean vector length of track directions, r = 0.79) and lowest at Abisko during spring (r = 0.35). Partial wind drift and partial compensation were recorded at Lund, with a similar effect size in spring and autumn, whilst possible wind drift effects at Abisko were obscured by the large directional scatter at this site. The results from Lund support the prediction that the high proportion of juveniles in autumn contributes to increase the directional scatter during this season, whilst there was no support for predictions of differential wind drift effects between seasons and situations with different goal distances. The most striking and surprising result was the exceedingly large scatter of flight directions at Abisko, particularly in spring. We suggest that such an exaggerated scatter may be associated with final approach orientation, where migrants reach their specific goals from all various directions by final navigation within a more wide-ranging goal region. The larger scatter of autumn flight directions at Abisko compared to Lund may be due to exploratory flights in variable directions being more common at initial departure from breeding sites than later during migratory passage. These surprising results highlight the importance of studying and analysing orientation during final approach to (and initial departure from) migratory goals for understanding the orientation systems of migratory birds.     

Occupational Accidents of Finnish-and Swedish-Speaking Workers in Finland: A Mental Model View

This article is based on 2 studies. The aim of the first study was to examine the differences in occupational accident frequency between the 2 main language groups in Finland. Based on 3 independent statistical data sets, it was shown that Swedish-speaking workers had about 40% fewer occupational accidents than Finnish-speaking workers. The aim of the second study was to confirm the difference at company level. A field study in the province of Vaasa with 14 small and medium-sized manufacturing companies revealed that the accident frequency of Swedish-speaking workers was 21% lower than that of Finnish-speaking workers.     

Towards democratic and effective forest governance? The discursive legitimation of forest certification in northern Sweden

Forest certification, particularly that of the Forest Stewardship Council (FSC), is frequently claimed to constitute an effective and democratic private governance arrangement for responsible forestry. It has, however, recently been questioned whether this view holds true for the northernmost countries, which have traditionally been presented as successful examples of forest certification. Yet there is little research on the perceived legitimacy of forest certification at the local level, which is where the standard implementation takes place. This paper examines how the perceived legitimacy of forest certification is created as well as challenged at the local level in Sweden, drawing on Steffek's [2009. Discursive legitimation in environmental governance. Forest Policy and Economics, 11, 313–318] conceptualisation of discursive legitimation and Bernstein's [2011. Legitimacy in intergovernmental and non-state global governance. Review of International Political Economy, 18 (1), 17–51] definition of legitimacy as well as semi-structured interviews with forest companies, reindeer husbandry (indigenous Sámi) and environmental non-governmental organisations (ENGOs). The results reveal that local ENGOs question the FSC's decision-making process and results, while both the ENGOs and reindeer husbandry see few opportunities to influence long-term forest management. These findings highlight the difficulties of managing power asymmetries in certification and the challenges involved when certification standards are translated from policy to practice.     

The downfall of mating: the effect of mate-carrying and flight muscle ratio on the escape ability of a pierid butterfly

In many species, the ability to evade predators is known to be periodically impaired by increased weight loads due to feeding and reproduction. Not only may extra weight reduce escape speed, but feeding and mating can also make the prey more noticeable to visually hunting predators. A number of butterfly species mate for hours, and if a mating couple is disturbed, one of the butterflies is responsible for flying, whereas its partner remains still. This study investigated the ability of male Pieris napi butterflies to fly while mating, with the prediction that mate carrying impairs flight ability compared to single flying males and that males with relatively high flight muscle ratios (FMR; male thorax mass/male + female body mass) will have better flight performance in copula. Our results clearly show that whereas single males always take off at steep angles and fly upwards, couples invariably have a negative take-off angle and rarely gain height. Moreover, landing height of the couples is positively associated with higher FMR. Hence, male flight ability when in copula is positively associated with a high relative thorax mass. Butterfly pairs may thus be at greater risk of predation as a consequence of their impaired flight ability, especially couples with critically low FMRs (<16%).     

Hassles on the job: a study of a job intervention with urban bus drivers

Epidemiological, psychophysiological and survey data all converge on the conclusion that driving a bus in an urban area is extremely stressful, posing serious health risks. We show that reductions in job hassles while operating buses largely account for the salutary effects of a job environment intervention designed to lessen traffic congestion, diminish passenger demands on drivers, and generally ease bus operation. This study also makes methodological contributions to the stress and health literature. Independent observers' assessments of changes in job hassles caused by a field intervention predict, in a longitudinal design, multimethodological markers of stress including blood pressure, heart rate, and a standardized self‐report index of stress. The value of utilizing job re‐design studies to more rigorously investigate stress and health is discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

Effective Transboundary Aquifer Areas: An Approach for Transboundary Groundwater Management

The natural complexity, heterogeneity, and extent of transboundary aquifers around the world, have led to controversy over which method or criteria should be used to identify and delineate their boundaries. Currently, there is no standard methodology that aquifer‐sharing countries can use to delineate the area of a transboundary aquifer. In the case of Mexico and Texas, Mexico uses administrative boundaries, whereas Texas uses geological boundaries. This paper proposes a method for delineation and prioritization of aquifers (or aquifer areas) called effective transboundary aquifer areas (ETAAs), which uses a combination of physical criteria (geological boundaries, topography, and hydrography) and the location and density of active water wells in the borderland between Mexico and Texas. This method identifies the area of priority (productivity area) in the aquifer using pumping patterns or hot spots regardless of the aquifer’s surficial geological limits, therefore offering a more effective, local and practical management option at the transboundary level. Different geological features or pumping patterns will have different sizes and locations of ETAAs within the same aquifer. In West Texas, which is dominated by bolsons, the method produces limited options for ETAAs, whereas in South Texas in the easternmost border the identified ETAAs are more significant.     

Herbicides based on 2,4-D: its behavior in agricultural environments and microbial biodegradation aspects. A review

Environmental Science and Pollution Research - One of the main herbicides used in the agricultural environments is 2,4-dichlorophenoxyacetic acid (2,4-D). It is a synthetic plant hormone auxin...     

Matrix effect in case of purification of oily waters by membrane separation combined with pre-ozonation

In the present study, oil in water emulsions (c_oil?=?100 ppm; d_{oil droplets}?<?2 μm) was purified with ozonation followed by microfiltration using polyethersulfone (PES) membrane (d_pore?=?0.2 μm). The effects of pre-ozonation on membrane microfiltration were investigated in detail both in case of ultrapure and model groundwater matrices, applying different durations (0, 5, 10, and 20 min) of pre-ozonation. Simultaneously, the effects of added inorganic water components on the combined method were investigated. Size distribution of oil droplets, zeta potentials, fluxes, and purification efficiencies were measured and fouling mechanisms were described in all cases. It was found that the matrix significantly affected the size distribution and adherence ability of oil droplets onto the membrane surface, therefore fouling mechanisms also were strongly dependent on the matrix. In case of low salt concentration, the total resistance was caused mainly by reversible resistance, which could be significantly reduced (eliminated) by pre-ozonation. In case of model groundwater matrix, nearly twice higher total resistance was measured, and irreversible resistance was dominant, because of the higher adhesion ability of the oil droplets onto the membrane surface. In this case, pre-ozonation resulted in much lower irreversible, but higher reversible resistance. Increased duration of pre-ozonation raised the total resistance and reduced the elimination efficiency (due to fragmented oil droplets and water soluble oxidation by-products) in both cases, therefore short pre-ozonation can be recommended both from economic and performance aspects.