Dodonaea viscosa (Sapindaceae) as a phytoremediator for soils contaminated by heavy metals in abandoned mines

Environmental Science and Pollution Research - Dodonaea viscosa (L.) Jacq. is a plant with a wide distribution that expands throughout almost all Mexican territory and is used in traditional...     

Predators exert top-down control of soybean aphid across a gradient of agricultural management systems.

The discovery of soybean aphid, Aphis glycines Matusumura, in North America in 2000 provided the opportunity to investigate the relative strength of top-down and bottom-up forces in regulating populations of this new invasive herbivore. At the Kellogg Biological Station Long Term Ecological Research site in agroecology, we contrasted A. glycines establishment and population growth under three agricultural production systems that differed markedly in disturbance and fertility regimes. Agricultural treatments consisted of a conventional-tillage high-input system, a no-tillage high-input system, and a zero-chemical-input system under conventional tillage. By selectively restricting or allowing predator access we simultaneously determined aphid response to top-down and bottom-up influences. Irrespective of predator exclusion, our agricultural manipulations did not result in bottom-up control of A. glycines intrinsic rate of increase or realized population growth. In contrast, we observed strong evidence for top-down control of A. glycines establishment and overall population growth in all production systems. Abundant predators, including Harmonia axyridis, Coccinella septempunctata, Orius insidiosus, and various predaceous fly larvae, significantly reduced A. glycines establishment and population increase in all trials. In contrast to other systems in which bottom-up forces control herbivore populations, we conclude that A. glycines is primarily controlled via top-down influences of generalist predators under a wide range of agricultural management systems. Understanding the role of top-down and bottom-up forces in this context allows agricultural managers to focus on effective strategies for control of this invasive pest.     

Optimal foraging and territorial defence in the Great Tit (Parus major)

Summary We describe an experiment designed to investigate the trade-off between foraging and territorial vigilance in the Great Tit. Captive territorial male Great Tits were observed while foraging in a large indoor aviary. They obtained food from two operant patches in which the supply of food was gradually depleted during a visit. We predicted that during control sessions the birds would switch between patches in such a way as to maximise their overall feeding rate. In experimental sessions, we introduced briefly a rival male as an intruder at the start of the test. The foraging male could see the rival only when travelling between patches and not while feeding within patches. We predicted that during experimental sessions birds would switch between patches more often than in control tests, sacrificing food intake for territorial vigilance. Three of the four males tested behaved in approximately the predicted manner. We discuss the use of an inverse optimality argument to provide a calibration of feeding against the benefit resulting from territorial vigilance.     

Carbon monoxide concentration forecasting in Santiago, Chile

In the city of Santiago, Chile, air quality is defined in terms of particulate matter with an aerodynamic diameter < or = 10 microm (PM10) concentrations. An air quality forecasting model based on past concentrations of PM10 and meteorological conditions currently is used by the metropolitan agency for the environment, which allows restrictions to emissions to be imposed in advance. This model, however, fails to forecast between 40 and 50% of the days considered to be harmful for the inhabitants every year. Given that a high correlation between particulate matter and carbon monoxide (CO) concentrations is observed at monitoring stations in the city, a model for CO concentration forecasting would be a useful tool to complement information about expected air quality in the city. Here, the results of a neural network-based model aimed to forecast maximum values of the 8-hr moving average of CO concentrations for the next day are presented. Forecasts from the neural network model are compared with those produced with linear regressions. The neural network model seems to leave more room to adjust free parameters with 1-yr data to predict the following year's values. We have worked with 3 yr of data measured at the monitoring station located in the zone with the worst air quality in the city of Santiago, Chile.     

Remote Sensing and GIS Technologies as Tools to Support Sustainable Management of Areas Devastated by Landslides

IKONOS panchromatic images from a single year were used to characterise the effects of an extreme rainstorm event on six mountain catchment areas in Venezuela. Image registrations were accomplished using topographic base maps at 1 : 5000 scale giving a mapping accuracy between 37 and 40 m. It was used an 8-bit channel for correction, rectification, filteration and tone enhancements.Landsliding was discerned in the affected watersheds using morphometric criteria, including the shape of the slope failure and its position, exposure bedrock in the scar and deposition of debris down-slope. This study is restricted to the impact analysis of the distribution of landslide erosion scars and the depositional processes on the valley floor. Remote sensing data were combined into a geographic information system (GIS) with planimetric data, contour lines, hydrology and vegetation types to evaluate the distribution of the scars and their effects on the highly populated areas located on the alluvial fans. Hillslope mass wasting induced mass movements, logging and increased the mud and silt in floodwaters affecting settlement down-slope.     

Characterization and determination of the odorous charge in the indoor air of a waste treatment facility through the evaluation of volatile organic compounds (VOCs) using TD–GC/MS

Municipal solid waste treatment facilities are generally faced with odorous nuisance problems. Characterizing and determining the odorous charge of indoor air through odour units (OU) is an advantageous approach to evaluate indoor air quality and discomfort. The assessment of the OU can be done through the determination of volatile organic compounds (VOCs) concentrations and the knowledge of their odour thresholds. The evaluation of the presented methodology was done in a mechanical–biological waste treatment plant with a processing capacity of 245.000 tons year^?1 of municipal residues. The sampling was carried out in five indoor selected locations of the plant (Platform of Rotating Biostabilizers, Shipping warehouse, Composting tunnels, Digest centrifugals, and Humid pre-treatment) during the month of July 2011. VOC and volatile sulphur compounds (VSCs) were sampled using multi-sorbent bed (Carbotrap, Carbopack X, Carboxen 569) and Tenax TA tubes, respectively, with SKC AirCheck 2000 pumps. The analysis was performed by automatic thermal desorption (ATD) coupled with a capillary gas chromatography (GC)/mass spectrometry detector (MSD). One hundred and thirty chemical compounds were determined qualitatively in all the studied points (mainly alkanes, aromatic hydrocarbons, alcohols, aldehydes, esters, and terpenes), from which 86 were quantified due to their odorous characteristics as well as their potentiality of having negative health effects. The application of the present methodology in a municipal solid waste treatment facility has proven to be useful in order to determine which type of VOC contribute substantially to the indoor air odorous charge, and thus it can be a helpful method to prevent the generation of these compounds during the treatment process, as well as to find a solution in order to suppress them.     

Collective group movement and leadership in wild black howler monkeys (Alouatta pigra)

Maintaining social cohesion through coordinating traveling time and direction is a primary benefit of group living in mammals. During a 15-month study, we investigated socioecological factors underlying leadership of collective group movements in three multimale–multifemale groups of black howler monkeys (Alouatta pigra) at Palenque National Park (PNP), Mexico. A total of 691 independent group movements across a variety of contexts were collected. Leadership of group movements was partially shared, with adult females initiating and leading group movements significantly more often than did adult males and juveniles, an outcome that has been observed among a diverse set of group living taxa. Adult females did not lead their group more often to feeding sites nor did they lead group movements more frequently when pregnant or lactating compared to when cycling, providing little evidence that energetic demands were the primary drivers underlying female leadership in this primate species. Instead, only one adult female in each social group was identified as a habitual leader of their group. These ‘leader’ females had the highest centrality eigenvectors among the adult group members in their group, suggesting an embedded leadership with the spatially widest connected adult group member emerging as recurrent leader of collective group movements.     

The Tourism Carrying Capacity of Underwater Trails in Isabel Island National Park, Mexico

The popularity of ecotourism in the marine protected areas of Mexico has increased over the last 10 years; in particular there is a large development of a SCUBA diving industry in the Mexican Pacific including Isabel Island. Given the risks associated with human activity in the marine environments around this island, we propose two ecotourism management strategies: (1) the creation and use of underwater trails, and (2) the estimation of the specific tourism carrying capacity (TCC) for each trail. Six underwater trails were selected in sites that presented elements of biological, geological, and scenic interest, using information obtained during field observations. The methodology used to estimate the TCC was based upon the physical and biological conditions of each site, the infrastructure and equipment available, and the characteristics of the service providers and the administrators of the park. Correction factors of the TCC included elements of the quality of the visit and the threat and vulnerability of the marine environment of each trail (e.g., divers’ expertise, size and distance between groups of divers, accessibility, wind, coral coverage). The TCC values ranged between 1,252 and 1,642 dives/year/trail, with a total of 8,597 dives/year for all six trails. Although these numbers are higher than the actual number of recreational visitors to the island (~1,000 dives per year), there is a need for adequate preventive management if the diving sites are to maintain their esthetic appeal and biological characteristics. Such management might be initially directed toward using only the sites and the TCC proposed here.     

Enantiospecific sublethal effects of the antidepressant fluoxetine to a model aquatic vertebrate and invertebrate

Many contaminants are chiral compounds with enantiomers that may differ markedly in environmental fate, bioavailability, and toxicity. Enantiospecific environmental fate and ecotoxicological information are lacking for many chiral contaminants. The primary objective of this investigation included an assessment of potential enantiospecific differences in sublethal standardized and behavioral responses of the model organisms Pimephales promelas (teleost) and Daphnia magna (crustacean) to the widely prescribed chiral antidepressant fluoxetine. Endpoints assessed included D. magna immobilization, reproduction, and grazing rate and P. promelas survival, growth, and feeding rate. S-Fluoxetine was found to be more toxic to sublethal standardized and behavioral endpoints in P. promelas, potentially because its primary active metabolite, S-norfluoxetine, is more potent than the same metabolite of R-fluoxetine in mammals. This was not observed for D. magna responses. This differential enantiospecific response between model organisms may have resulted from closer target homology between mammals and fish than between mammals and crustaceans. P. promelas feeding rate, an ecologically relevant and mode-of-action related response, was the most sensitive endpoint tested for R- and S-fluoxetine with 10% effect concentration (EC10) values (+/-SE) of 16.1 (+/-20.2) and 3.7 (+/-4.6) microg l(-1), respectively. Up to a 9.4-fold difference in toxicity between enantiomers was observed; P. promelas growth EC10s (+/-SE) for R- and S-fluoxetine were 132.9 (+/-21.2) and 14.1 (+/-8.1) microg l(-1), respectively. Such differences in sublethal responses to fluoxetine enantiomers suggest that enantiospecific toxicity and mode-of-action related responses that are ecologically relevant (e.g., feeding rate) should be considered in future ecological hazard and risk assessments for chiral contaminants.