Age-specific social dominance affects habitat use by breeding American redstarts (Setophaga ruticilla): a removal experiment

Summary By removing older males from their breeding territories, we tested the hypothesis that age-related dominance behavior influenced the pattern of habitat selection by breeding American redstarts Setophaga ruticilla (Aves: Parulinae). Fifteen older male redstarts removed in five experimental replicates during three breeding seasons were replaced by ten yearling and five older males; no redstart males of either age colonized the control sites during the same time periods, although two yearlings disappeared. Significantly more yearling males (67%, n=9) colonized the vacated areas than were present in the redstart population at large (26.8%, n=209). We reject the alternative hypothesis that yearling male redstarts occupy different habitats from older males because of age-related (innate) habitat preferences. Redstarts that colonized the territories made vacant by our removals (i.e., floaters) were a behaviorally heterogeneous group of animals. The presence of both yearling and older male floaters indicates that suitable habitat is limiting for this species and that intraspecific competitive interactions are important in habitat distribution, and potentially in population regulation.     

Viability Analysis of Reef Fish Populations Based on Limited Demographic Information

Abstract:  Marine protected areas (MPAs) that allow some degree of artisanal fishing have been proposed to control the overexploitation of marine resources while allowing extraction by local communities. Nevertheless, the management of MPAs is often impaired by the absence of data on the status of their resources. We devised a method to estimate population growth rates with the type of data that are usually available for reef fishes. We used 7 years of spatially explicit abundance data on the leopard grouper ( Mycteroperca rosacea ) in an MPA in the Gulf of California, Mexico, to construct a matrix population model that incorporated the effects of El Niño/La Niña Southern Oscillation on population dynamics. An environmental model that estimated different demographic estimates for El Niño and La Niña periods performed better than a single-environment model, and a single-habitat model performed better than a model that considered different depths as different habitats. Our results suggest that the population of the leopard grouper off the main island of the MPA is not viable under present conditions. Although the impact of fishing on leopard grouper populations in the MPA has not yet been established, fishing should be closed as a precautionary measure at this island if a priority of the MPA is to ensure the sustainability of its fish populations.     

Carbon Monitoring Costs and their Effect on Incentives to Sequester Carbon through Forestry

Technically, forestry projects have thepotential to contribute significantly tothe mitigation of global warming, but manysuch projects may not be economicallyattractive at current estimates of carbon(C) prices. Forest C is, in a sense, a newcommodity that must be measured toacceptable standards for the commodity toexist. This will require that credible Cmeasuring and monitoring procedures be inplace. The amount of sequestered C that canbe claimed by a project is normallyestimated based on sampling a number ofsmall plots, and the precision of thisestimate depends on the number of plotssampled and on the spatial variability ofthe site. Measuring C can be expensive andhence it is important to select anefficient C-monitoring strategy to makeprojects competitive in the C market. Thispaper presents a method to determinewhether a forestry project will benefitfrom C trading, and to find the optimalmanagement strategy in terms of forestcycle length and C-monitoring strategyA model of an Acacia mangiumplantation in southern Sumatra, Indonesiais used to show that forestry projects canbe economically attractive under a range ofconditions, provided that the project islarge enough to absorb fixed costs.Modeling results indicate that between 15and 38 Mg of Certified Emission Reductions(CERs) per hectare can be captured by thesimulated plantation under optimalmanagement, with optimality defined asmaximizing the present value of profitsobtained from timber and C. The optimalcycle length ranged from 12 to 16 years andthe optimal number of sample plots rangedfrom 0 to 30. Costs of C monitoring (inpresent-value terms) were estimated to bebetween 0.45 (Mg C)^-1 to 2.11 (MgC)^-1 depending on the spatialvariability of biomass, the variable costsof C monitoring and the discount rate.     

Ritter’s dry-bed dam-break flows: positive and negative wave dynamics

Dam-break flood waves are associated with major environmental disasters provoked by the sudden release of water stored in reservoirs. Ritter found in 1892 an analytical solution to the wave structure of an ideal fluid released during an instantaneous dam failure, propagating over initially dry horizontal terrain. This solution, though ideal, hence frictionless, is widely used to test numerical solutions of the Shallow Water Equations (SWE), and as educational tool in courses of fluid mechanics, given that it is a peculiar case of the Riemann problem. However, the real wave structure observed experimentally differs in a major portion of the wave profile, including the positive and negative fronts. Given the importance of an accurate prediction of the dam break wave, the positive and negative wave portions originating from the breaking of a dam with initially dry land on the tailwater reach are revisited in this work. First, the propagation features of the dry-front are investigated using an analytical boundary-layer type model (Whitham/Dressler/Chanson model) constructed matching an (outer) inviscid dynamic wave to an (inner) viscous diffusive wave. The analytical solution is evaluated using an accurate numerical solution of the SWE produced using the MUSCL-Hancock finite-volume method, which is tested independently obtaining the solution based on the discontinuous Galerkin finite-element method. The propagation features of the negative wave are poorly reproduced by the SWE during the initial stages of dam break flows, and, thus, are then investigated using the Serre–Green–Naghdi equations for weakly-dispersive fully non-linear water waves, which are solved using a finite volume-finite difference scheme.     

Heavy metal content in rubbish bags used for separate collection of biowaste

The heavy metal content of several rubbish bags used to collect the organic fraction of municipal solid waste (OFMSW) is shown in this paper. Nowadays, several public awareness campaigns carried out by municipalities have promoted rubbish bags based mainly on their appearance, without concern for their heavy metal content. A high amount of heavy metals was detected in some polyethylene bags promoted in different campaigns for OFMSW source-sorted collection, while compostable bags presented low quantities of heavy metals. Some other rubbish bags, as well as commercial bags, were also analysed for comparison. These results should be taken into account before promoting the use of one or other type of bag. Moreover, the rubbish bag manufacturers should reduce the heavy metal content in order to avoid heavy metal scattering in the environment, and also to reduce the consumption of raw materials.     

BENEFITS OF ITERATIVE WATER SUPPLY FORECASTING IN THE WASHINGTON,D.C., METROPOLITAN AREA1

The three largest water utilities in the Washington, D.C., metropolitan area (WMA) rely on the Potomac River and its reservoirs for water supply. These utilities have committed to a periodic review of the system's adequacy to meet future demands. In 1990, 1995, 2000, and again in 2004 (for publication in 2005) the utilities requested that the Interstate Commission on the Potomac River Basin (ICPRB) conduct a 20‐year water demand and resource adequacy study to fulfill this need. The selection of the five‐year interval provides multiple benefits. It allows regular updates and incorporation of recent demographic forecasts, and it increases visibility and understanding of the adequacy of the region's water resources. It also provides adequate time to conduct research on the physical system and to incorporate modifications based on this research into subsequent studies. The studies and lessons learned are presented in this case study of the WMA. The work has been a natural outgrowth of a long history of cooperative water supply planning and management among the main WMA water utilities and ICPRB.     

Junk mail in residential homes in the United States: Insights from a sub-urban home in California

Although systematic studies tracking junk mail sent to residential homes are lacking, available reports indicate it is a growing problem in many urban centers worldwide. Junk mail increases the number of trees harvested each year, consumes a substantial amount of energy, causes pollution to air, water and soil and wastes a substantial amount of time sorting, mailing and recycling. Junk mail collected at one residence in the United States for a period of one full year is analyzed to find out the main contributors to this urban problem, what residents should do to reduce or eliminate it. Results indicate that three major businesses are responsible for over 70% of total junk mail sent (n = 1255) including credit card, mortgage and insurance corporations. To encourage environmental sustainability, several strategies that can help businesses reduce junk mail are suggested including new advertising techniques, use of other outlets like billboards, outreach events in social functions and adopting eco-friendly techniques in any junk mail production. Considering the revenue and jobs created from junk mail business, and the absence of government regulation and lack of consensus amongst individuals, environmental groups and businesses on what needs to be done; individuals are urged to explore ways to mitigate the problem and a number of recommendations are given.     

Geochemistry of leachates from the El Fraile sulfide tailings piles in Taxco, Guerrero, southern Mexico

Leachates from the El Fraile tailings impoundment (Taxco, Mexico) were monitored every 2 months from October 2001 to August 2002 to assess the geochemical characteristics. These leachates are of interest because they are sometimes used as alternative sources of domestic water. Alternatively, they drain into the Cacalotenango creek and may represent a major source of metal contamination of surface water and sediments. Most El Fraile leachates show characteristics of Ca–SO₄, (Ca+Mg)–SO₄, Mg–SO₄ and Ca–(SO₄+HCO₃) water types and are near-neutral (pH=6.3–7.7). Some acid leachates are generated by the interaction of meteoric water with tailings during rainfall events (pH=2.4–2.5). These contain variable levels of SO₄ ²⁻ (280–29,500 mg l⁻¹) and As (<0.01–12.0 mg l⁻¹) as well as Fe (0.025–2352 mg l⁻¹), Mn (0.1–732 mg l⁻¹), Zn (<0.025–1465 mg l⁻¹) and Pb (<0.01–0.351 mg l⁻¹). Most samples show the highest metal enrichment during the dry seasons. Leachates used as domestic water typically exceed the Mexican Drinking Water Guidelines for sulfate, hardness, Fe, Mn, Pb and As, while acidic leachates exceed the Mexican Guidelines for Industrial Discharge Waters for pH, Cu, Cd and As. Speciation shows that in near-neutral solutions, metals exist mainly as free ions, sulfates and bicarbonates, while in acidic leachates they are present as sulfates and free ions. Arsenic appears as As^(V) in all samples. Thermodynamic and mineralogical evidence indicates that precipitation of Fe oxides and oxyhydroxides, clay minerals and jarosite as well as sorption by these minerals are the main processes controlling leachate chemistry. These processes occur mainly after neutralization by interaction with bedrock and equilibration with atmospheric oxygen.