Effects of pre-exposure to ultraviolet-B radiation on responses of tomato (Lycopersicon esculentum cv. New Yorker) to ozone in ambient and elevated carbon dioxide

Patterns of environmental change in the biosphere include concurrent and sequential combinations of increasing ultraviolet (UV-B) and ozone (O(3)) at increasing carbon dioxide (CO(2)) levels; long-term changes are resulting mainly from stratospheric O(3) depletion, greater tropospheric O(3) photochemical synthesis, and increasing CO(2) emissions. Effects of selected combinations were evaluated in tomato (Lycopersicon esculentum cv. New Yorker) seedlings using sequential exposures to enhanced UV-B radiation and O(3) in differential CO(2) concentrations. Ambient (7.2 kJ m(-2 )day(-1)) or enhanced (13.1 kJ m(-2) day(-1)) UV-B fluences and ambient (380 microl l(-1)) or elevated (600 microl l(-1)) CO(2) were imposed for 19 days before exposure to 3-day simulated O(3) episodes with peak concentrations of 0.00, 0.08, 0.16 or 0.24 microl l(-1) O(3) in ambient or elevated CO(2). CO(2) enrichment increased dry mass, leaf area, specific leaf weight, chlorophyll concentration and UV-absorbing compounds per unit leaf area. Exposure to enhanced UV-B increased leaf chlorophyll and UV-absorbing compounds but decreased leaf area and root/shoot ratio. O(3) exposure generally inhibited growth and leaf photosynthesis and did not affect UV-absorbing compounds. The highest dose of O(3) eliminated the stimulating effect of CO(2) enrichment after ambient UV-B pre-exposure on leaf photosynthesis. Pre-exposure to enhanced UV-B mitigated O(3) damage to leaf photosynthesis at elevated CO(2).     

Rapid assessment of postfire plant invasions in coniferous forests of the western United States.

Fire is a natural part of most forest ecosystems in the western United States, but its effects on nonnative plant invasion have only recently been studied. Also, forest managers are engaging in fuel reduction projects to lessen fire severity, often without considering potential negative ecological consequences such as nonnative plant species introductions. Increased availability of light, nutrients, and bare ground have all been associated with high-severity fires and fuel treatments and are known to aid in the establishment of nonnative plant species. We use vegetation and environmental data collected after wildfires at seven sites in coniferous forests in the western United States to study responses of nonnative plants to wildfire. We compared burned vs. unburned plots and plots treated with mechanical thinning and/or prescribed burning vs. untreated plots for nonnative plant species richness and cover and used correlation analyses to infer the effect of abiotic site conditions on invasibility. Wildfire was responsible for significant increases in nonnative species richness and cover, and a significant decrease in native cover. Mechanical thinning and prescribed fire fuel treatments were associated with significant changes in plant species composition at some sites. Treatment effects across sites were minimal and inconclusive due to significant site and site x treatment interaction effects caused by variation between sites including differences in treatment and fire severities and initial conditions (e.g., nonnative species sources). We used canonical correspondence analysis (CCA) to determine what combinations of environmental variables best explained patterns of nonnative plant species richness and cover. Variables related to fire severity, soil nutrients, and elevation explained most of the variation in species composition. Nonnative species were generally associated with sites with higher fire severity, elevation, percentage of bare ground, and lower soil nutrient levels and lower canopy cover. Early assessments of postfire stand conditions can guide rapid responses to nonnative plant invasions.     

Sometimes less is more: Directed coping with interpersonal stressors at work

Within the coping literature, researchers have long been interested in identifying ways in which individuals can improve their coping efforts, making them more effective and thereby reducing the harmful effects of stressful encounters. Although Lazarus and Folkman's transactional model has greatly advanced understanding of the coping process, there continues to be methodological and conceptual challenges that have hindered understanding of the mechanisms behind effective coping. Addressing these issues in the use of a novel approach of analyzing variation in coping (i.e., directed coping) at both the coping event and person coping levels, the current study examined the process of coping with work stress and the beneficial coping outcomes associated with using a directed coping strategy. A total of 143 nurses completed up to 12 weekly surveys online, reporting on weekly stressful interpersonal conflicts and how they coped with them. Results from multilevel analyses supported predictions that greater directed coping at both the level of the coping event and person is associated with improvements in occupational health outcomes even after controlling for other coping factors. Implications of these results are discussed in relation to future research on coping effectiveness and workplace applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Nutrient cycling by fish supports relatively more primary production as lake productivity increases

Animals can be important in nutrient cycling in particular ecosystems, but few studies have examined how this importance varies along environmental gradients. In this study we quantified the nutrient cycling role of an abundant detritivorous fish species, the gizzard shad (Dorosoma cepedianum), in reservoir ecosystems along a gradient of ecosystem productivity. Gizzard shad feed mostly on sediment detritus and excrete sediment-derived nutrients into the water column, thereby mediating a cross-habitat translocation of nutrients to phytoplankton. We quantified nitrogen and phosphorus cycling (excretion) rates of gizzard shad, as well as nutrient demand by phytoplankton, in seven lakes over a four-year period (16 lake-years). The lakes span a gradient of watershed land use (the relative amounts of land used for agriculture vs. forest) and productivity. As the watersheds of these lakes became increasingly dominated by agricultural land, primary production rates, lake trophic state indicators (total phosphorus and chlorophyll concentrations), and nutrient flux through gizzard shad populations all increased. Nutrient cycling by gizzard shad supported a substantial proportion of primary production in these ecosystems, and this proportion increased as watershed agriculture (and ecosystem productivity) increased. In the four productive lakes with agricultural watersheds (>78% agricultural land), gizzard shad supported on average 51% of phytoplankton primary production (range 27-67%). In contrast, in the three relatively unproductive lakes in forested or mixed-land-use watersheds (>47% forest, <52% agricultural land), gizzard shad supported 18% of primary production (range 14-23%). Thus, along a gradient of forested to agricultural landscapes, both watershed nutrient inputs and nutrient translocation by gizzard shad increase, but our data indicate that the importance of nutrient translocation by gizzard shad increases more rapidly. Our results therefore support the hypothesis that watersheds and gizzard shad jointly regulate primary production in reservoir ecosystems.     

Levels and trends of brominated flame retardants in the Arctic

Polybrominated diphenyl ethers (PBDEs) containing two to seven bromines are ubiquitous in Arctic biotic and abiotic samples (from zooplankton to polar bears (Ursus maritimus) and humans; air, soil, sediments). The fully brominated decabromodiphenyl ether (BDE-209), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA) and polybrominated biphenyls (PBBs) are also present in biotic and abiotic samples. Spatial trends of PBDEs and HBCD in top predators are similar to those seen for polychlorinated biphenyls (PCBs) and indicate western Europe and eastern North America as source regions. Concentrations of tetra- to heptaBDEs have increased significantly in North American and Greenlandic Arctic biota and in Greenland freshwater sediments paralleling trends seen further south. For BDE-209, increasing concentrations in Greenlandic peregrine falcons (Falco peregrinus) and in dated lake sediment cores in the Canadian Arctic have been seen during the 1990s. BDE-47, -99, -100 and -153 are observed to biomagnify in Arctic food webs. summation operatorPBDE concentrations in Arctic samples are lower than in similar sample types from more southerly regions and are one or more orders of magnitude lower than summation operatorPCB concentrations except for some levels for air. Air and harbor sediment results for PBDEs indicate that there are local sources near highly populated areas within the Arctic. Findings of PBBs on moss and TBBPA on an air filter, and that both are found in biota at high trophic levels indicates that these compounds may also reach the Arctic by long-range atmospheric transport. Based on the evidence of their presence in the Arctic and indications that most if not all are undergoing long-range transport, these brominated flame retardants (BFRs) have characteristics that qualify them as POPs according to the Stockholm Convention.     

Antimicrobial potential of the ionophore monensin on freshwater biofilm bacteria

Microorganisms play key roles in stream ecosystems, but comparatively little is known about the resilience of freshwater bacterial communities and their susceptibility to the chemical by-products of agricultural land use. Antibiotics used in the agricultural sector are of particular concern and have been detected in waterways associated with agricultural land. Despite widespread agricultural intensification globally and the sector's high antibiotic use, the effects of agricultural antibiotic by-products on stream microbial communities have yet to be characterised. We investigated the impacts of the antibiotic monensin on microbial biofilm communities in a simulated contamination event using streamside-replicated channels. A 24-h pulse experiment in flow channels precolonised by stream biofilm microbial communities contrasted the effects of monensin concentrations ranging from realistic to extreme toxicity levels (1–550 ug L^?1). Biofilm community composition was characterised immediately before and after the pulse for several weeks using automated ribosomal intergenic spacer analysis. Despite applying acutely toxic levels of monensin, only limited effects to biofilm community composition were detected immediately after antibiotic application, and these disappeared within 4 days. Rather, temporal factors drove biofilm differences, highlighting the overriding importance of wider, catchment-level, physiochemical hydrological influences on structuring freshwater biofilm communities, as opposed to localised and sporadic agricultural surface runoff contamination events containing antibiotics.     

Wetlands mitigation: Partnership between an electric power company and a federal wildlife refuge

Nine hectares (23 acres) of a degraded section of Patuxent Research Refuge in Laurel, Maryland, USA, were converted to wetland habitat by the Baltimore Gas and Electric Company in 1994. The wetlands were created as mitigation for 5.7 ha (14 acres) of wetlands that were impacted as part of the construction of an 8.5-km (5.3-mile) 500-kV overhead transmission line on the refuge. The area consists of a created forested wetland of 5.5 ha (13.5 acres), a seasonally inundated green-tree reservoir of 7.6 ha (6.5 acres), and an impounded pond wetland of 1.2 ha (3 acres). Construction included the planting of 6131 trees, 4276 shrubs, and 15,102 emergent plants. Part of the site has been studied intensively since completion and survival of trees and shrubs after two years was 88%. Measurements of these transplants have shown growth greater than on other created sites in Maryland. Grasses and other herbaceous vegetation were dominant plants in the meter-square plots in the first two years of sampling of the created forested wetland. Wildlife surveys for birds, mammals, amphibians, and reptiles have revealed diverse communities. Although these communities represent species consistent with open habitat, more typical forest species should colonize the area as it undergoes succession into a more mature forested wetland. The creation, management, and research of this mitigation site represents an excellent example of a partnership between a private electric power company and a federal wildlife refuge. This partnership has increased local biodiversity and improved regional water quality of the Patuxent River and the Chesapeake Bay.     

The effects of type A behavior dimensions and optimism on coping strategy,health, and performance

Type A behavior dimensions and optimism were examined as predictors of health and performance. In addition, this research also explored the ways that Type As and optimists cope with stressful situations. The achievement striving dimension of the Type A behavior pattern and optimism were positively related to class performance, while the anger/hostility dimension was positively related to the health symptom of anxiety. Optimism, on the other hand, was negatively related to anxiety. The interaction of achievement striving and optimism was negatively related to anxiety. Additionally, while achievement striving was positively related to problem-focused coping, irritability showed a negative association with problem-focused coping strategy. The results of this study provide insights for both individuals and organizations regarding how to cope with daily stresses in order to lower health risks and improve performance.