Spatial and mass balanced trophic models of La Rinconada Marine Reserve (SE Pacific coast), a protected benthic ecosystem: Management strategy assessment

Steady-state, dynamic, and spatial models were constructed for the benthic system of La Rinconada Marine Reserve off northern Chile (SE Pacific coast). We examined data on biomass, P/B ratios, catches, food spectrum, consumption, and the dynamics of commercial and non-commercial populations using three theoretical frameworks: Ecopath, Ecosim, and Ecospace. The biomass of the scallop Argopecten purpuratus and the clam Tagelus dombeii were the most relevant compartments of the studied ecosystem. Among the carnivores, the functional crab group Cancer spp. was the most relevant. The Rhodophyta was the dominant macroalga compartment of the system. The results obtained using mixed trophic impacts (MTI) showed that the predatory snail Thais chocolata propagated higher magnitudes of direct and indirect effects on the other species or functional groups. The sea star Luidia magallanica and Rhodophyta had the least effects on the remaining compartments. According to the Ecosim estimates (increasing mortality by fishing), the scallop A. purpuratus had the highest impact on the other compartments. The Ecospace model showed similar qualitative and quantitative effects for changes in biomass under three different exploitation scenarios (by subsystems and globally). Nevertheless, the greatest changes were provoked by using the top-down control and the vulnerabilities estimated by Ecosim. System recovery times were highest with increased mortality of the asteroid L. magallanica and the carnivorous snail T. chocolata, suggesting that the sea star could be considered to be a top predator with a top-down control. The F_MSY estimated for the scallop A. purpuratus was close to the F_i originally entered in Ecopath, limiting the design and execution of an exploitation plan within ecologically sustainable boundaries. The situation was different (F_MSY ? F_i) for the other commercial species, making possible multi-species exploitation programs. The Ecospace trophic-spatially explicit model shows a similar pattern of direct and indirect effects generated when exerting exploitation separately by subsystems. Therefore, habitat rotation of fisheries is not justified.     

Stormwater treatment: examples of computational fluid dynamics modeling

Control of rainfall-runoff particulate matter (PM) and PM-bound chemical loads is challenging; in part due to the wide gradation of PM complex geometries of many unit operations and variable flow rates. Such challenges and the expense associated with resolving such challenges have led to the relatively common examination of a spectrum of unit operations and processes. This study applies the principles of computational fluid dynamics (CFD) to predict the particle and pollutant clarification behavior of these systems subject to dilute multiphase flows, typical of rainfall-runoff, within computationally reasonable limits, to a scientifically acceptable degree of accuracy. The Navier-Stokes (NS) system of nonlinear partial differential equations for multiphase hydrodynamics and separation of entrained particles are solved numerically over the unit operation control volume with the boundary and initial conditions defined and then solved numerically until the desired convergence criteria are met. Flow rates examined are scaled based on sizing of common unit operations such as hydrodynamic separators (HS), wet basins, or filters, and are examined from 1 to 100 percent of the system maximum hydraulic operating flow rate. A standard turbulence model is used to resolve flow, and a discrete phase model (DPM) is utilized to examine the particle clarification response. CFD results closely follow physical model results across the entire range of flow rates. Post-processing the CFD predictions provides an in-depth insight into the mechanistic behavior of unit operations by means of three dimensional (3-D) hydraulic profiles and particle trajectories. Results demonstrate the role of scour in the rapid degradation of unit operations that are not maintained. Comparisons are provided between measured and CFD modeled results and a mass balance error is identified. CFD is arguably the most powerful tool available for our profession since continuous simulation modeling.     

Design-based estimation in environmental surveys with positional errors

The recent increased availability of information about the micro-geographic positions of population units in environmental surveys has led to important developments in spatial sampling methodologies and, as a result, has improved the estimation accuracy. In real data, however, information about the location of units is often affected by inaccuracy about their exact spatial positions, and these non-sampling errors can affect the estimation procedure. This paper aims to investigate the effects of positional errors on total estimation through a Monte-Carlo simulation study based on real populations of trees. Starting from perfect positioning, we examine two typical types of coarsening that frequently impact two different species of trees. The simulation results show that the exploitation of spatial information to estimate population totals continues to be relevant in the context of environmental surveys, even in the presence of inaccuracies.     

Egg antimicrobials, embryo sex and chick phenotype in the yellow-legged gull

Maternal effects through albumen quality are largely unexplored, despite the fundamental role that albumen exerts as source of proteins and water, as well as for antimicrobial defence of the embryo. We analysed the variation of two major albumen antimicrobials, avidin and lysozyme, by extracting samples from freshly laid eggs of the yellow-legged gull (Larus michahellis) and by correlating their levels to egg features. Lysozyme concentration increased along the laying sequence, while avidin concentration decreased. Both antimicrobials declined during the season. In addition, avidin concentration declined from first- to last-laid male eggs, whereas the opposite was true among the female eggs. We also analysed chick body mass and size and immune response, in relation to albumen antimicrobial levels in their original egg while controlling for potential covariation between egg quality and rearing conditions by cross-fostering eggs between nests. Tarsus length decreased with avidin concentration, particularly early in the season. Avidin concentration negatively predicted tarsus length of chicks and the phytohaemagglutinin response of females, but not males. However, chick phenotype did not covary with lysozyme albumen concentration. This is the first study where maternal effects mediated by albumen antimicrobials are investigated in relation to both sex and egg features in any wild bird species. Whether the observed patterns of variation in antimicrobial concentration are the by-product of maternal physiological constraints, or reflect adaptive allocation strategies, cannot be ascertained. The covariation between chick cell-mediated immunity and albumen avidin concentration might be causal, according to the documented effects of albumen proteins on immunity in other species.     

Ecological sexual segregation in fallow deer (Dama dama): a multispatial and multitemporal approach

We questioned the different interpretations of ecological sexual segregation from a novel perspective, i.e., by carrying out diverse temporal and spatial scale analyses within a long-term study (1984–2003). Thus we combined spatial (small/large) and temporal (small/large) scale analyses to identify the factors generating sexual segregation in fallow deer in San Rossore, Italy. The study site was divided into an eastern sector characterized by human disturbance (DS) and a western undisturbed sector (US). According to census data, human presence increased in DS from 1984, and while females gradually abandoned it, males remained—thus supporting the predation risk hypothesis (large spatial and temporal scale)—and actually increased their presence in DS, where they seemingly benefited from a lower female density. This supported the indirect competition hypothesis. The analysis of data on a large temporal and small spatial scale confirmed that intersexual competition, in particular for grass, was higher in a crowded pasture in US. Observations by means of radio-telemetry of 23 adult females and 25 adult males (1997–2001, reduced temporal and large spatial scale) showed that large scale segregation was relevant during the day and disappeared at night, when disturbance was absent and also the females reached DS. This also supported the predation risk hypothesis. Moreover, sexes showed different habitat choices inside DS at night, thus supporting the forage selection hypothesis (small spatial and temporal scale). In conclusion, failure to address the whole set of combinations of spatial and temporal scale analyses would have led to monocausal explanations of ecological sexual segregation.     

Early onset of vegetation growth vs. rapid green-up: impacts on juvenile mountain ungulates

Seasonal patterns of climate and vegetation growth are expected to be altered by global warming. In alpine environments, the reproduction of birds and mammals is tightly linked to seasonality; therefore such alterations may have strong repercussions on recruitment. We used the normalized difference vegetation index (NDVI), a satellite-based measurement that correlates strongly with aboveground net primary productivity, to explore how annual variations in the timing of vegetation onset and in the rate of change in primary production during green-up affected juvenile growth and survival of bighorn sheep (Ovis canadensis), Alpine ibex (Capra ibex), and mountain goats (Oreamnos americanus) in four different populations in two continents. We indexed timing of onset of vegetation growth by the integrated NDVI (INDVI) in May. The rate of change in primary production during green-up (early May to early July) was estimated as (1) the maximal slope between any two successive bimonthly NDVI values during this period and (2) the slope in NDVI between early May and early July. The maximal slope in NDVI was negatively correlated with lamb growth and survival in both populations of bighorn sheep, growth of mountain goat kids, and survival of Alpine ibex kids, but not with survival of mountain goat kids. There was no effect of INDVI in May and of the slope in NDVI between early May and early July on juvenile growth and survival for any species. Although rapid changes in NDVI during the green-up period could translate into higher plant productivity, they may also lead to a shorter period of availability of high-quality forage over a large spatial scale, decreasing the opportunity for mountain ungulates to exploit high-quality forage. Our results suggest that attempts to forecast how warmer winters and springs will affect animal population dynamics and life histories in alpine environments should consider factors influencing the rate of changes in primary production during green-up and the timing of vegetation onset.     

Periodic inspection on crop sprayers: results according to age of sprayers

The objectives of the IPP Project--Periodic Inspection on Crop Sprayers--are to develop methods for sprayer certification, analyze quality on spray operation, propose an inspection system for crop sprayers in Brazil, improve environmental quality on spray operation, and reduce costs on chemical control for plant protection systems. Periodic inspections on crop sprayers are performed in several countries and are compulsory in most of them, and it is becoming an important tool for improvement and optimization of use of chemicals. The IPP Project in Brazil is funded by FAPESP--Funda??o de Amparo à Pesquisa do Estado de S?o Paulo. The results so far showed that all the sprayers presented failures. However, most of them could be approved with minor services. As an example, 56.6% of the sprayers with more than 2 years of use presented leaks, 47% of them had damaged hoses and 80.5% presented bad tips (nozzles). These results indicate the need for better procedures of use and maintenance of sprayers, justifying the periodic inspection system.     

First principles of the MameLuke multi-actor modelling framework for land use change, illustrated with a Philippine case study

This paper presents the first principles of the MameLuke framework, an agent-based modelling framework for studying environmental issues and land use and cover change (LUCC). The MameLuke framework enhances the understanding of the relationship between societal processes and LUCC by modelling individual and group decisions and human-environment interactions. The framework allows for the transformation of real-life stories into computerised models following a predetermined sequence. By doing so, the framework allows for a truly integrative approach, because it is not bound to any particular scientific discourse. Even better, the framework enables its users to combine scientific discourses regarding human decisions and behaviour on multiple scales and levels. The agents (actors and locations) in the framework are heterogeneous. This heterogeneity of agent behaviour is established by dividing the agents into categories. If an agent is a member of an agent category or combination of categories, it has access to a defined set of implementable actions. The actions are constructed out of potential option paths (POPs) and potential option nodes (PONs). The whole of POPs represent a theoretical construct of agent behaviour and decisions that the framework user wishes to explore. The POP defines a sequence of PONs. The PON is a transaction interface between an initialising agent and a recipient agent where they exchange material and immaterial capital. This paper explains the basic architecture of the MameLuke framework and shows its applicability with a model of a Philippine case study. This case study concerns the dynamics of migration and deforestation. It is part of a larger study on land use change in the San Mariano watershed area at the forest fringe of the Sierra Madre mountains in the Philippines.     

Assessment of natural or enhanced in situ bioremediation at a chlorinated solvent-contaminated aquifer in Italy: a microcosm study

A microcosm study was used to assess the potential for in situ natural or enhanced bioremediation at a chloroethane- (i.e., tetrachloroethane, TeCA) and chloroethene-contaminated (i.e., tetrachloroethene, PCE; trichloroethene, TCE) groundwater in Northern Italy. All the live microcosms were positive for dechlorination, indicating the presence of an active native dechlorinating population in the subsurface. All the tested electron donors (i.e., yeast extract, lactate, butyrate, hydrogen) promoted enhanced dechlorination of chlorinated contaminants. Lactate- and butyrate-amended microcosms performed the best, and also dechlorinated the solvents past cis-dichloroethene (cis-DCE). The microcosm bioaugmented with a PCE-dechlorinating mixed culture containing Dehalococcoides spp. dechlorinated groundwater contaminants to DCE, vinyl chloride (VC), and ethene (ETH). In conclusion, results from this microcosm study indicate the potential for enhancing full dechlorination at the contaminated site, through a proper addition of a suitable electron donor (e.g., lactate or butyrate) and/or through bioaugmentation with a Dehalococcoides-containing culture.     

Field intercomparison of precipitation measurements performed within the framework of the Pan European Intensive Monitoring Program of EU/ICP Forest

A 6-month field intercomparison study on precipitation measurements was performed at Schagerbrug near the west coast in the Netherlands. Twenty bulk sampling systems and two wet-only samplers were evaluated on accuracy, sampling strategy and performance under field conditions. Bulk precipitation fluxes of NO3-, NH4+, H+ and Kjeldahl-N generally could be determined with a greater accuracy than bulk precipitation fluxes of SO4(2-), Na+, Cl-, Mg2+, Ca2+, Alkalinity and H+. Bulk precipitation fluxes of K+ generally had the lowest accuracy. Only 20% of the sampling systems differed less than 10% from the best estimate, whereas most systems (60%) differed more than 20% from the best estimate. The inaccuracy induced by the sampling system appeared to be much larger than that resulting from the analysis of the samples by different laboratories as determined by ring-tests.