Large eddy simulation of flow and scalar transport in a vegetated channel

Predicting flow and mass transport in vegetated regions has a broad range of applications in ecology and engineering practice. This paper presents large eddy simulation (LES) of turbulent flow and scalar transport within a fully developed open-channel with submerged vegetation. To properly represent the scalar transport, an additional diffusivity was introduced within the canopy to account for the contribution of stem wakes, which were not resolved by the LES, to turbulent diffusion. The LES produced good agreement with the velocity and concentration fields measured in a flume experiment. The simulation revealed a secondary flow distributed symmetrically about the channel centerline, which differed significantly from the circulation in a bare channel. The secondary circulation accelerated the vertical spread of the plume both within and above the canopy layer. Quadrant analysis was used to identify the form and shape of canopy-scale turbulent structures within and above the vegetation canopy. Within the canopy, sweep events contributed more to momentum transfer than ejection events, whereas the opposite occurred above the canopy. The coherent structures were similar to those observed in terrestrial canopies, but smaller in scale due to the constraint of the water surface.     

Laboratory investigation of <Emphasis Type="Italic">Fallopia</Emphasis> × <Emphasis Type="Italic">bohemica</Emphasis> fruits dispersal by watercourses

Seed and fruit dispersal along watercourses favours the long-distance migration of invasive species, not only for aquatic or wetland species, but also for terrestrial wind-dispersed plants, like the Japanese knotweed. The present paper aims at investigating the role of watercourses in the dispersal of the knotweed due to its frequent occurrence on riverbanks and production of fertile achenes (type of fruit of the Japanese knotweed). This dispersal occurs along two steps after the fruits deposit on the water surface: floatation first and then sinking towards the bottom of the watercourse. Regarding the first step, the effects of agitation of the water, temperature, surface tension and luminosity on the achenes floatability are experimentally studied. While no influence of luminosity is observed, an increase of temperature greatly decreases the floating time. Floating time also decreases as the contact between water and the fruit is enhanced (through submersion of achenes, agitation of the water or lower surface tension). Regarding the second step, the fall velocity of the fruits in water at rest is measured and appears to be independent of the seed history (floating time). 3D helical motions are systematically observed with constant tangential velocity with respect to the falling velocity. The trajectory of the fruits in a shear flow is then measured and the evolution of their velocity components along the sinking process is discussed. Finally, the contribution of both steps to the long-distance migration of the seeds is estimated.     

Assessment of physicochemical characteristics of Ganga Canal water quality in Uttarakhand

Assessment of physicochemical parameters of Ganga Canal water was carried out during 2012–2013 at Haridwar (Uttarakhand) with two different sites, i.e., Bhimgoda Barrage (site 1—control site) and Bahadrabad (site 2—contaminated site), where canal water flows with loads of pollution from highly commercial and industrial areas. During investigation, maximum turbidity (287.72 ± 56.28 JTU), total solids (1167.60 ± 303.90 mg l^?1), free CO₂ (1.88 ± 0.22 mg l^?1), total hardness (60.14 ± 1.13 mg l^?1), pH (7.1 ± 0.13), nitrate (0.048 ± 0.010), nitrite (0.019 ± 0.001), biochemical oxygen demand (2.866 ± 1.098), chemical oxygen demand (6.8 ± 2.61) and phosphate (0.087 ± 0.015), while minimum velocity (1.71 ± 0.19 ms^?1), transparency (0.12 ± 0.08 m) and dissolved oxygen (7.95 ± 0.44 mg l^?1) were recorded in monsoon season at site 2 in comparison with site 1. The mean values of these parameters were compared with WHO and ISI standards and found significant differences (p < 0.05) in the mean values of turbidity, total solids, pH, dissolved oxygen, free CO₂ and total hardness with sampling sites. The turbidity of both the sites 1 and 2 was recorded above the permissible limit. Turbidity of site 2 is much higher than of site 1, so it is counted as more polluted. The values of the studied parameters were more during monsoon season and summer season at site 2 as compared to site 1. The results indicated that most of the physicochemical parameters from Ganga Canal system were within or at periphery in comparison with permissible limit of ISI and WHO for drinking water and therefore may be suitable for domestic purposes, but it requires perceptible consideration due to intense changes in climate and increase in pollution.     

Urban development,environmental vulnerability and CRZ violations in India: impacts on fishing communities and sustainability implications in Mumbai coast

Coastal Regulations in India are traced back to the UN Conference on Human Environment, held in Stockholm in 1972. The Environment Protection Act (EPA) 1986 was enacted to implement India’s commitments as a signatory. The Coastal Regulation Zone (CRZ) Notification of 1991 was made under the provisions of the EPA in order to protect coastal environments and social and livelihood security of fishing community. This paper assesses the effects of CRZ rules and violations in the Mumbai Metropolitan Region, which has experienced tremendous growth due to the rapid industrialization and urbanization. This process has led to the destruction of mangroves and other important species of fish which play a crucial role in sustaining the coastal ecology and urban biodiversity; high population density and uneven growth have exacerbated adverse environmental and socioeconomic consequences. The Koli (fishing community) in this region faces huge problems of survival and sustenance in small-scale fishing, due to the rampant commercial fishing by big trawlers and large-scale dumping of waste materials by the industries surrounding the vicinity into the sea. In small but significant ways, the fishing communities through their traditional commons-based resource management and livelihood systems protect the coastal ecology and help the cities in reducing their carbon footprints. On the basis of primary field research in Thane–Mulund Creek Bhandup, Chimbai, and Sewri, this paper attempts to assess CRZ violations taking place on coastal areas and is causing damage to the coastal ecology. The research specifically has focused on the particular fishing-related activities and spaces—such as: jetties, parking of boats, access to sea, weaving and drying of nets, landing grounds, drying and cleaning of fish that are more affected by encroachment of seashore area and by CRZ rules violations. It evaluates the actions taken by Maharashtra Coastal Zone Management Authority and Bombay Municipal Corporation while implementing rules and making Integrated Coastal Zone Management plan for management of marine environment. It raises broader issues relating to the contradictions and complementarities involved in ICZM plans vis-a-vis management of biodiversity, within a larger context of rapid urbanization and demands for real estate growth. The paper argues that urban biodiversity management requires clear valuation of the long-term ecological and socioeconomic benefits of sustenance of coastal ecology and related livelihoods.     

Organic certification for shrimp value chains in Ca Mau,Vietnam: a means for improvement or an end in itself?

Eco-certification has been used as a tool to mitigate adverse effects of aquaculture production and might thus be understood as a private approach to sustainable ecosystem management. In production forests in Ca Mau, Vietnam, where mangrove have suffered degradation despite legal protection, different projects have targeted reversing this trend by means of private certification using the ‘Naturland’ organic standard as a reference. So far the outcomes have, however, been proven unsatisfactory. With the aim to better understand the reasons for these poor outcomes, a survey of forty households was conducted in a production forest in Rach Goc commune, Ngoc Hien District. We evaluated farmers’ perceptions on mangrove management, the drivers guiding shrimp farming, and whether there was a difference between participants and non-participants in a former ‘Naturland’ organic project. To complement the survey, a range of stakeholders involved in shrimp value chains were interviewed to better understand the terms and benefits of certification. The results of this survey suggested that, when applied to shrimp–mangrove farming systems in production forests in Ca Mau, ‘eco-certification’ and associated benefits are not very satisfactory. The survey results revealed that certified farms do not show significant differences to non-certified farms in terms of social and environmental benefits. As far as the implementation process was concerned, the survey results showed that a failure to integrate local farmers as participants consequently resulted in households becoming ‘objects’ for certification and not project partners with equal weight and power. It appears that rather than being a tool for improvement, ‘Naturland’ certification for shrimp–mangrove farming systems in Ca Mau’s production forests has become an end in itself.     

Assessment of the hunting of mammals using local ecological knowledge: an example from the Brazilian semiarid region

The hunting of wild animals remains a common activity in various parts of the world, especially in rural communities with poor socioeconomic conditions. To investigate patterns of mammal hunting, this study adopted a rural community located in semiarid Brazil as a model to test whether variables such as perceived abundance, activity period (day or night) and animal biomass could influence the consumption potential of mammal taxa. For this study, a checklist/interview technique using 32 photographs of mammals recorded in the region and two photographs of species that did not occur in the region, which acted as “control” species, was used, in addition to other visual stimuli and free lists. All species presented in the photographs, with the exception of the “control” species, were recognized as occurring in the region. Fourteen species were cited as being those most hunted locally. The species cited as most hunted had an average perceived abundance higher than the group of the least-hunted species. However, there was no significant relationship between hunting of a species and its locally perceived abundance. No significant difference in hunting pressure between diurnal and nocturnal species was found, nor was a relationship between animal biomass and hunting pressure observed. Our findings suggest that perceived abundance is an important factor for choosing a resource fauna, but other factors such as intended use, meat flavor and vulnerability to hunting, among others, may influence the potential use of a species.     

Social-ecological resilience and the quest for sustainability as object of science

The term ‘sustainability science’ has been employed to refer to a scientific trend, movement or program aimed at studying problems related to human–nature interactions. However, since it does not have its own set of principles for knowledge building and lack of a definition of a study object, sustainability science is not a science, at least in the usual sense of the word. A study object is the conceptual delimitation of the problems tackled by a science, and therefore, its search in the context of a science of sustainability requires exploring different notions of sustainability. This article presents different perspectives on the concept of sustainability and analyzes the viability to assume them as study object of sustainability science. Such exploration demands concepts based on a processual ontology that directs the researcher toward the dynamic, historic and temporal and social-ecological character of problems of unsustainability. The concept of social-ecological resilience seems to comply with such requirements.     

Comparing contaminated property redevelopment for mandatory and Voluntary Cleanup Programs in California

This study uses California data to compare redevelopment for properties subject to mandatory and voluntary cleanup. CalSites are subject to the CERCLA liability approach, while properties in the Voluntary Cleanup Program (VCP) are subject to a risk-based approach (RBA) that allows some contamination to remain for non-residential redevelopment. The expectation is that VCPs will show a greater proportion of industrial redevelopment, which has the least stringent standard, and a smaller proportion of residential redevelopment. The results show an overall trend toward more residential redevelopment of contaminated properties, but consistent with expectations, the trend is weaker for VCP properties than CalSites.     

Sexual conflict over fertilizations: female bluethroats escape male paternity guards

Extra-pair copulations create a potential for sexual conflict in pair-bonding birds. Here we report an experimental study of the bluethroat, Luscinia s. svecica, in which the throat ornament of males was blackened with Nyanzol D in order to reduce their sexual attractiveness and thus increase the sexual conflict over fertilizations. In an earlier study, we showed that males blackened before pairing had a lower success in attracting social mates than controls, whereas males blackened after pairing guarded their mates more intensely and sang less than controls. Here we add behavioural data from one more year on males blackened after pairing and corroborate our previous finding that the manipulation caused males to guard their mates more intensely and advertise less for additional mates. Blackened males did not suffer more intrusions from neighbouring males than did controls. Paternity analyses of the combined data set, using multilocus DNA fingerprinting and microsatellite typing, revealed that blackened males lost significantly more paternity than controls. There was also a tendency for blackened males to show a lower success in achieving extra-pair fertilizations. These results indicate that females have the upper hand in the sexual conflict over fertilizations, as females paired with unattractive males can achieve more extra-pair paternity despite the greater constraint posed by the intensified mate guarding. Still, within the blackened group, there were some indications that males guarding more intensely and singing less had higher paternity than males guarding less and singing more, suggesting a marginal positive effect of guarding for unattractive males. Male mate guarding must nevertheless be considered a best-of-a-bad-job strategy in this species. Received: 4 December 1997 / Accepted after revision: 14 June 1998     

Microbial diversity and dynamics during methane production from municipal solid waste

The objectives of this study were to characterize development of bacterial and archaeal populations during biodegradation of municipal solid waste (MSW) and to link specific methanogens to methane generation. Experiments were conducted in three 0.61-m-diameter by 0.90-m-tall laboratory reactors to simulate MSW bioreactor landfills. Pyrosequencing of 16S rRNA genes was used to characterize microbial communities in both leachate and solid waste. Microbial assemblages in effluent leachate were similar between reactors during peak methane generation. Specific groups within the Bacteroidetes and Thermatogae phyla were present in all samples and were particularly abundant during peak methane generation. Microbial communities were not similar in leachate and solid fractions assayed at the end of reactor operation; solid waste contained a more abundant bacterial community of cellulose-degrading organisms (e.g., Firmicutes). Specific methanogen populations were assessed using quantitative polymerase chain reaction. Methanomicrobiales, Methanosarcinaceae, and Methanobacteriales were the predominant methanogens in all reactors, with Methanomicrobiales consistently the most abundant. Methanogen growth phases coincided with accelerated methane production, and cumulative methane yield increased with increasing total methanogen abundance. The difference in methanogen populations and corresponding methane yield is attributed to different initial cellulose and hemicellulose contents of the MSW. Higher initial cellulose and hemicellulose contents supported growth of larger methanogen populations that resulted in higher methane yield.