Air quality management in Portugal: example of needs and available tools

The Framework Directive (FWD) and the proposed Daughter Directives are the newest legislative instruments concerning a new political strategy and air quality management approach for Europe. Additionally, the member countries of the United Nations Economic Commission for Europe have included the concepts of critical load and level for planning air pollution abatement strategies and as a base of international agreements concerning limitation of the emissions of air pollutants. These concepts imply an accurate knowledge about pollutants deposition fluxes. The paper describes the main needs and the tools available to define a strategy of air quality management in Portugal. Two study cases are presented: (1) extensive monitoring plan to assess the impact of an urban incinerator plant; and (2) contribution to a methodology to estimate critical levels for a coastal region in Portugal. These different approaches allowed illustrating the complexity of the implementation of an air pollution management strategy.     

Biodegradable Blends with Potential Use in Packaging: A Comparison of PLA/Chitosan and PLA/Cellulose Acetate Films

Poly(lactic acid) (PLA) is a biodegradable polymer that exhibits high elastic modulus, high mechanical strength, and feasible processability. However, high cost and fragility hinder the application of PLA in food packaging. Therefore, this study aimed to develop flexible PLA/acetate and PLA/chitosan films with improved thermal and mechanical properties without the addition of a plasticizer and additive to yield extruder compositions with melt temperatures above those of acetate and chitosan. PLA blends with 10, 20, and 30 wt% of chitosan or cellulose acetate were processed in a twin-screw extruder, and grain pellets were then pressed to form films. PLA/acetate films showed an increase of 30 °C in initial degradation temperature and an increase of 3.9 % in elongation at break. On the other hand, PLA/chitosan films showed improvements in mechanical properties as an increase of 4.7 % in elongation at break. PLA/chitosan film which presented the greatest increase in elongation at break proved to be the best candidate for application in packaging.     

Life history strategy of a southern European population of brown shrimp (Crangon crangon L.): evidence for latitudinal changes in growth phenology and population dynamics

This study provides a comprehensive examination of the life cycle dynamics of the brown shrimp (Crangon crangon L.) in the Mondego estuary, Portugal, a habitat located near the southern edge of the range of this species in European waters. The phenology of all life stages was documented (from the occurrence of ovigerous females, developing embryos, planktonic larvae and benthic post-larvae), and migration patterns of larvae into and out of the estuary were examined. Temperature-dependent functions of egg and larval development were combined with data on field abundance to predict the timing and magnitude of occurrence of larvae and recruits. Compared to brown shrimp at higher latitudes, southern conspecifics grow slower, mature earlier and have smaller brood sizes, and larvae have a more protracted settlement period. The Mondego estuary, besides acting as nursery area, is a dynamic platform for C. crangon to use in different stages, sizes and seasons.     

Species diversity reduces parasite infection through cross-generational effects on host abundance

With growing interest in the effects of biodiversity on disease, there is a critical need for studies that empirically identify the mechanisms underlying the diversity-disease relationship. Here, we combined wetland surveys of host community structure with mechanistic experiments involving a multi-host parasite to evaluate competing explanations for the dilution effect. Sampling of 320 wetlands in California indicated that snail host communities were strongly nested, with competent hosts for the trematode Ribeiroia ondatrae predominating in low-richness assemblages and unsuitable hosts increasingly present in more diverse communities. Moreover, competent host density was negatively associated with increases in snail species richness. These patterns in host community assembly support a key prerequisite underlying the dilution effect. Results of multigenerational mesocosm experiments designed to mimic field-observed community assemblages allowed us to evaluate the relative importance of host density and diversity in influencing parasite infection success. Increases in snail species richness (from one to four species) had sharply negative effects on the density of infected hosts (-90% reduction). However, this effect was indirect; competition associated with non-host species led to a 95% reduction in host density (susceptible host regulation), owing primarily to a reduction in host reproduction. Among susceptible hosts, there were no differences in infection prevalence as a function of community structure, indicating a lack of support for a direct effect of diversity on infection (encounter reduction). In monospecific conditions, higher initial host densities increased infection among adult hosts; however, compensatory reproduction in the low-density treatments equalized the final number of infected hosts by the next generation, underscoring the relevance of multigenerational studies in understanding the dilution effect. These findings highlight the role of interspecific competition in mediating the relationship between species richness and parasite infection and emphasize the importance of field-informed experimental research in understanding mechanisms underlying the diversity-disease relationship.     

Effects on larval crabs of exposure to algal toxin via ingestion of heterotrophic prey

We tested whether ingesting toxic algae by heterotrophic prey affected their nutritional value to crab larval predators, using toxic algal strains that are either ingested directly by larval crabs or rejected by them. Ingestion of toxic strains of the dinoflagellates Alexandrium andersoni and A. fundyense by the rotifer Brachionus plicatilis was confirmed. Rotifers having ingested either algal type for five days were fed to freshly hatched larvae of three crab species, with larval survival and stage durations determined. For both algal/rotifer treatments in all three crab species, larvae fed algae directly died during the first zoeal stage, while those fed rotifers that had been fed either algal strain survived to the experiment’s end (zoeal stage 3). Survival was lower, and stage duration longer, for larvae fed rotifers cultured on toxic algae when compared to those fed non-toxic algae. The role of toxic algae in the planktonic food web may be influenced by its direct or indirect ingestion by larval crabs.     

Artificial light at night (ALAN) causes variable dose-responses in a sandy beach isopod

Artificial Light at Night (ALAN) is expanding worldwide, and the study of its influence remains limited mainly to documenting impacts, overlooking the variation in key characteristics of the artificial light such as its intensity. The potential dose–response of fitness-related traits to different light intensities has not been assessed in sandy beach organisms. Hence, this study explored dose-responses to ALAN by exposing the intertidal sandy beach isopod Tylos spinulosus to a range of light intensities at night: 0 (control), 20, 40, 60, 80 and 100 lx. We quantified the response of this species at the molecular (RNA:DNA ratios), physiological (absorption efficiency) and organismal (growth rate) levels. Linear and non-linear regressions were used to explore the relationship between light intensity and the isopod response. The regressions showed that increasing light intensity caused an overall?~?threefold decline in RNA:DNA ratios and a?~?threefold increase in absorption efficiency, with strong dose-dependent effects. For both response variables, non-linear regressions also identified likely thresholds at 80 lx (RNA:DNA) and 40 lx (absorption efficiency). By contrast, isopod growth rates were unrelated (unaltered) by the increase in light intensity at night. We suggest that ALAN is detrimental for the condition of the isopods, likely by reducing the activity and feeding of these nocturnal organisms, and that the isopods compensate this by absorbing nutrients more efficiently in order to maintain growth levels.

     

Simulating dynamic and mixed-severity fire regimes: A process-based fire extension for LANDIS-II

Fire regimes result from reciprocal interactions between vegetation and fire that may be further affected by other disturbances, including climate, landform, and terrain. In this paper, we describe fire and fuel extensions for the forest landscape simulation model, LANDIS-II, that allow dynamic interactions among fire, vegetation, climate, and landscape structure, and incorporate realistic fire characteristics (shapes, distributions, and effects) that can vary within and between fire events. We demonstrate the capabilities of the new extensions using two case study examples with very different ecosystem characteristics: a boreal forest system from central Labrador, Canada, and a mixed conifer system from the Sierra Nevada Mountains (California, USA). In Labrador, comparison between the more complex dynamic fire extension and a classic fire simulator based on a simple fire size distribution showed little difference in terms of mean fire rotation and potential severity, but cumulative burn patterns created by the dynamic fire extension were more heterogeneous due to feedback between fuel types and fire behavior. Simulations in the Sierra Nevada indicated that burn patterns were responsive to topographic features, fuel types, and an extreme weather scenario, although the magnitude of responses depended on elevation. In both study areas, simulated fire size and resulting fire rotation intervals were moderately sensitive to parameters controlling the curvilinear response between fire spread and weather, as well as to the assumptions underlying the correlation between weather conditions and fire duration. Potential fire severity was more variable within the Sierra Nevada landscape and also was more sensitive to the correlation between weather conditions and fire duration. The fire modeling approach described here should be applicable to questions related to climate change and disturbance interactions, particularly within locations characterized by steep topography, where temporally or spatially dynamic vegetation significantly influences spread rates, where fire severity is variable, and where multiple disturbance types of varying severities are common.     

Effects of insecticides used in strawberries on stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi (Hymenoptera: Apidae)

Environmental Science and Pollution Research - The use of pesticides is considered one of the most important threats to pollinators, especially since they are widely used in agriculture for pest...     

Pharmaceutical compound removal efficiency by a small constructed wetland located in south Brazil

Environmental Science and Pollution Research - The fate of pharmaceuticals during the treatment of effluents is of major concern since they are not completely degraded and because of their...