The stability of trophic mass-balance models of marine ecosystems: a comparative analysis

Dynamic simulations of 18

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mass-balance marine trophic models are used to explore the stability of systems when briefly impacted by a fishery on the key ‘wasp–waist' populations occurring at intermediate trophic levels. The results are related to different ecosystem goal functions previously identified as representative of three attributes of ecosystems development: community complexity, homeostasis and energetics. System recovery time, the time required for all functional groups to returns to baseline level, and here used as a measure of model stability, was inversely correlated to Finn's Cycling Index, i.e. to the fraction of ecosystem throughput that is recycled, and to the mean length of trophic pathways in the systems. Systems with higher capacity to recycle detritus are systems with a higher ability to recover from perturbations. The results are in agreement with the E.P. Odum's theory of ecosystem development, where recycling is interpreted as a chief positive feedback mechanism that contributes to stability in the mature systems by preventing overshoots and destructive oscillations due to external impacts.     

Social and hospital costs of patients admitted to a university hospital in Brazil due to motorcycle crashes

Objective: This study aimed to investigate the social and hospital costs of patients treated at a public hospital who were motorcycle crash victims.

Method: This prospective study was on 68 motorcycle riders (drivers or passengers), who were followed up from hospital admission to 6 months after the crash. A questionnaire covering quantitative and qualitative questions was administered.

Results: Motorcycle crash victims were responsible for 12% of the institution's hospital admissions; 54.4% were young (18–28 years of age); 92.6% were the drivers; 91.2% were male; and 50% used their motorcycles as daily means of transportation. Six months afterward, 94.1% needed help from someone; 83.8% had changed their family dynamics; and 73.5% had not returned to their professional activities. Among the injuries, 94.7% had some type of fracture, of which 53.5% were exposed fractures; 35.3% presented temporary sequelae; and 32.4% presented permanent sequelae. They used the surgical center 2.53 times on average, with a mean hospital stay of 18 days. The per capita hospital cost of these victims’ treatment was US$17,481.50.

Conclusion: The social and hospital costs were high, relative to the characteristics of a public institution. Temporary or permanent disability caused changes to family dynamics, as shown by the high numbers of patients who were still away from their professional activities more than 6 months afterward.     

Gastroenteric Viruses Detection in a Drinking Water Distribution-to-Consumption System in a Low-Income Community in Rio de Janeiro

Food and Environmental Virology - The availability of drinking water is one of the main determinants of quality of life, disease prevention and the promotion of health. Viruses are important agents...     

Numerical modeling of simultaneous tracer release and piscicide treatment for invasive species control in the Chicago Sanitary and Ship Canal,Chicago, Illinois

In December 2009, during a piscicide treatment targeting the invasive Asian carp in the Chicago Sanitary and Ship Canal, Rhodamine WT dye was released to track and document the transport and dispersion of the piscicide. In this study, two modeling approaches are presented to reproduce the advection and dispersion of the dye tracer (and piscicide), a one-dimensional analytical solution and a three-dimensional numerical model. The two approaches were compared with field measurements of concentration and their applicability is discussed. Acoustic Doppler current profiler measurements were used to estimate the longitudinal dispersion coefficients at ten cross sections, which were taken as reference for calibrating the longitudinal dispersion coefficient in the one-dimensional analytical solution. While the analytical solution is fast, relatively simple, and can fairly accurately predict the core of the observed concentration time series at points downstream, it does not capture the tail of the breakthrough curves. These tails are well reproduced by the three-dimensional model, because it accounts for the effects of dead zones and a power plant which withdraws nearly 80 % of the water from the canal for cooling purposes before returning it back to the canal.     

Effects of a shipwreck on the zooplankton community in a port region of the Amazon

Environmental Science and Pollution Research - The port regions of the Amazon are subject to environmental impacts high shipping traffic. In October 2015, a cargo ship containing 5000 oxen sank in...     

Environmental monitoring of water resources around a municipal landfill of the Rio Grande do Sul state,Brazil

Environmental Science and Pollution Research - In Brazil, landfills are commonly used as a method for the final disposal of waste that is compliant with the legislation. This technique, however,...     

Effect of impeller type and agitation on the performance of pilot scale ASBR and AnSBBR applied to sanitary wastewater treatment

The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1 m³, treated 0.65 m³ sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were assessed for each reactor configuration: flat-blade turbine impeller, 45°-inclined-blade turbine impeller and helix impeller, as well as two agitation rates: 40 and 80 rpm, resulting in a combination of six experimental conditions. In addition, the ASBR was also operated at 20 rpm with a flat-blade turbine impeller and the AnSBBR was operated with a draft tube and helix impeller at 80 and 120 rpm. To quantify how impeller type and agitation rate relate to substrate consumption rate, results obtained during monitoring at the end of the cycle, as well as the time profiles during a cycle were analyzed. Increasing agitation rate from 40 rpm to 80 rpm in the AnSBBR improved substrate consumption rate whereas in the ASBR this increase destabilized the system, likely due to granule rupture caused by the higher agitation. The AnSBBR showed highest solids and substrate removal, highest kinetic constant and highest alkalinity production when using a helix impeller, 80 rpm, and no draft tube. The best condition for the ASBR was achieved with a flat-blade turbine impeller at 20 rpm. The presence of the draft tube in the AnSBBR did not show significant improvement in reactor efficiency. Furthermore, power consumption studies in these pilot scale reactors showed that power transfer required to improve mass transfer might be technically and economically feasible.     

Changes in Microbial Community Structure and Soil Biological Properties in Mined Dune Areas During Re-vegetation

The aim of this study was to describe the impact of re-vegetation on the restoration of microbial community structure and soil microbiological properties in sand dunes that had been affected by mining activity. Soil samples were collected during the dry and rainy seasons from a chronosequence (1, 9, 21 years) of re-vegetated dunes using a single preserved dune as a reference. The composition of the fatty acid methyl esters and soil microbial properties were evaluated. The results showed that the changes in microbial community structure were related to seasonal variations: biomarkers of Gram-positive bacteria were higher than Gram-negative bacteria during the dry season, showing that this group of organisms is more tolerant to these stressful conditions. The microbial community structure in the natural dune was less affected by seasonal variation compared to the re-vegetated areas, whereas the opposite was observed for microbiological properties. Thus, in general, the proportion of saprobic fungi was higher in the natural dune, whereas Gram-negative bacteria were proportionally more common in the younger areas. Although over time the re-vegetation allows the recovery of the microbial community and the soil functions, these communities and functions are different from those found in the undisturbed areas.     

“Winter” aggregations, colony cycle, and seasonal phenotypic change in the paper wasp Polistes versicolor in subtropical Brazil

Social wasps from temperate zones have clear annual colony cycles, and the young queens hibernate during winter. In the subtropics, the only previously reported evidence for the existence of “hibernation” is the facultative winter aggregations of females during harsh climate conditions. As in temperate-zone species analyzed so far, we show in this study that in the paper wasp, Polistes versicolor, a subtropical species, body size increases as an unfavorable season approaches. Our morphological studies indicate that larger females come from winter aggregations—that is, they are new queens. Multivariate analyses indicate that size is the only variable analyzed that shows a relationship to the differences. Given the absence of a harsh climate, we suggest that the occurrence of winter aggregations in tropical P. versicolor functions to allow some females to wait for better environmental conditions to start a new nest, rather than all being obliged to start a new nest as soon as they emerge.