The potential of biogas production from municipal solid waste in a tropical climate

The objective of this study was to estimate the potential of organic municipal solid waste generated in an urban setting in a tropical climate to produce biogas. Five different categories of wastes were considered: fruit waste, food waste, yard waste, paper waste, and mixed waste. These fractions were assessed for their efficiency for biogas production in a laboratory-scale batch digester for a total period of 8 weeks at a temperature of 15–30 °C. During this period, fruit waste, food waste, yard waste, paper waste, and mixed waste were observed to produce 0.15, 0.17, 0.10, 0.08, and 0.15 m³ of biogas per kilogram of volatile solids, respectively. The biogas produced and caloric value of each feedstock was in the range of 1.25?×?10^?3 m³ (17 kWh)/cap/day (paper waste) to 15?×?10^?3 m³ (170 kWh)/cap/day (mixed waste). Paper waste produced the least (<1×10^?3(<17.8 kWh)/cap/day), and mixed waste produced the highest methane yield (10?×?10^?3 m³ (178 kWh)/cap/day). Thus, mixed waste was found to be more efficient than other feedstocks for biogas and methane production; this was mainly related to the better C/N ratio in mixed waste. Taking the total waste production in Jimma into account, the total mixed organic solid waste could produce 865?×?10³ m³ (5.4 m³/capita) of biogas or 537?×?10³ m³ (3.4 m³/capita) of methane per year. The total caloric value of methane production potential from mixed organic municipal solid waste was many times higher than the total energy requirement of the area.     

Conservation of biodiversity through taxonomy,data publication,and collaborative infrastructures

Taxonomy is the foundation of biodiversity science because it furthers discovery of new species. Globally, there have never been so many people involved in naming species new to science. The number of new marine species described per decade has never been greater. Nevertheless, it is estimated that tens of thousands of marine species, and hundreds of thousands of terrestrial species, are yet to be discovered; many of which may already be in specimen collections. However, naming species is only a first step in documenting knowledge about their biology, biogeography, and ecology. Considering the threats to biodiversity, new knowledge of existing species and discovery of undescribed species and their subsequent study are urgently required. To accelerate this research, we recommend, and cite examples of, more and better communication: use of collaborative online databases; easier access to knowledge and specimens; production of taxonomic revisions and species identification guides; engagement of nonspecialists; and international collaboration. “Data‐sharing” should be abandoned in favor of mandated data publication by the conservation science community. Such a step requires support from peer reviewers, editors, journals, and conservation organizations. Online data publication infrastructures (e.g., Global Biodiversity Information Facility, Ocean Biogeographic Information System) illustrate gaps in biodiversity sampling and may provide common ground for long‐term international collaboration between scientists and conservation organizations.     

Territory and group sizes in Eurasian beavers (Castor fiber): echoes of settlement and reproduction?

According to current theories of territoriality, an animal is expected to defend the smallest area that can provide resources for maximisation of reproduction, known as the economically defendable area. In group territorial species however, the strategies behind resource defence are likely to be more complex with corporate territoriality, cooperative breeding, delayed dispersal and intra-group competition all potentially playing a role. Here we examined group territoriality in a social herbivorous rodent, the Eurasian beaver Castor fiber. Beavers in our study do not inhabit economically defendable territories. Instead the sequence of arrival of pairs into unoccupied areas seems to play a more important role in determining the size of the territory, whereas group size is determined by past reproductive success. We argue that the settlement pattern and reproductive history have a lasting impact in the territorial system of beavers due to a combination of the low adult mortality, high dispersal costs, and avoidance of resource depletion.R.D. Campbell and F. Rosell contributed equally to this work     

Optical properties of the uropygial gland secretion: no evidence for UV cosmetics in birds

Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently, it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion. Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds. We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling through plumage reflectance. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Mate guarding and copulation behaviour in monogamous and polygynous blue tits: do males follow a best-of-a-bad-job strategy?

This study investigates the importance of mate guarding for males and females in the facultatively polygynous blue tit Parus caeruleus. We present observational data in combination with a paternity analysis using DNA fingerprinting to show that (1) male blue tits guard their mate, since they stay closer to their mate, initiate fewer flights and follow their mate more often during the female's presumed fertile period; (2) polygynous males do not suffer more from lost paternity despite lower mate guarding; (3) in monogamous pairs there is either no relation or a positive relation (depending upon the variable measured) between measures of mate guarding intensity and the proportion of extra-pair young in the nest; and (4) monogamous males that are more often followed by their fertile female suffered less from lost paternity. We conclude that, despite mate guarding, paternity seems to be largely under female control and unattractive males guarding their mate are making the best of a bad situation. Experimental evidence is provided showing that when males were temporarily removed from their territory, their mate suffered from increased harassment from neighbouring males that intruded in the territory and tried to copulate with the female. Almost all of these copulation attempts were unsuccessful because females refused to copulate. We conclude that mate guarding may be beneficial for females because harassment by neigbouring males is prevented.     

The effects of air pollution on work loss and morbidity

The pending revision of U.S. air standards and the analytic requirements of Executive Order 12291 will force regulators to examine closely the data showing possible human health effects from air pollution. A number of studies have investigated the relationship between air pollution and human mortality using an epidemiological approach. This study uses a data set on individuals, the Health Interview Survey, conducted by the National Center for Health Statistics, to examine the relationship between air pollution and various measures of morbidity. Regressions run with the total sample and a subsample of male nonsmokers indicate a statistically significant relationship between particulates and both work loss and restricted activity days. Further analysis considering alternative functional forms also indicates that the ambient level of particulates is still significantly related to the measure of morbidity.     

Copper toxicity to different field-collected cladoceran species: intra- and inter-species sensitivity

The acute copper sensitivity of 44 European freshwater cladocerans, from four families (Daphniidae, Bosminidae, Macrothricidae, Chydoridae) and 13 genera (Daphnia, Ctenodaphnia, Ceriodaphnia, Simocephalus, Scapholeberis, Bosmina, Acantholeberis, Alona, Acroperus, Chydorus, Eurycercus, Disparalona and Pleuroxus) were assayed. The 48-h EC(50)s of field-collected organisms tested in reconstituted standard laboratory water ranged from 5.3 to 70.6 mug Cu L(-1). Only among Ctenodaphnia were significant intra-species differences observed. Significant inter-species differences were noted among Alonina and Daphnia. Between all genera tested, a maximum of a 12-fold difference in copper sensitivity was noted. Most animals were more sensitive than a laboratory D. magna clone. A weak non-significant increasing trend was noted between mean cladoceran 48-h EC(50) and ambient copper concentration of the different aquatic systems, suggesting acclimation/adaptation in the field. A positive relationship was also observed between the 48-h EC(50) of the field-collected cladoceran species (without the Chydoridae family) and the size of the organisms.     

Cd and Zn Concentration in Hybrid Poplar Foliage and Leaf Beetles Grown on Polluted Sediment-Derived Soils

Foliar Cd and Zn concentrations of hybrid poplars commonlyplanted on sediment-derived soils were assessed in field circumstances. Selected sites covered a range of soil types andplantation characteristics. Reference data for foliar concentrations were established from samples taken in a tree-nursery. Even in the reference situation a large variationin foliar Cd and Zn concentrations was observed, with relative standard deviations in the order of 15%. Foliar concentrations of Cd and Zn in poplars growing on sediment-derived soils increased during the growing season. The accumulation rate was markedly higher on polluted sediment-derived soils than in thereference situation. Poplars grown on polluted sedimentderived soils showed elevated and deviating foliar Cd and Znconcentrations (>7.5 mg Cd kg^-1 DW and 320 mg Zn kg^-1 DW). A thin unpolluted covering layer did not influence foliarconcentrations. Regardless of site characteristics, poplarage, species or clone, a significant positive relation wasfound between soil and foliar concentration for Zn and to alesser extent for Cd. Bioconcentration factors for Cd and Znwere higher than one in baseline situations, but mostly lowerthan one on polluted sediment-derived soils. Cd:Zn ratio wason the average twice as high as in the soil. Leaf beetlesshowed normal body concentrations for Zn, but higher Cdconcentrations than in reference situations. BCFs were lowerthan one on sediment-derived soils. Foliar results indicateda possible threat in long-term habitat development of poplarplantations. This conclusion was confirmed by the significanthigher Cd concentrations in leaf beetles grown on poplarswith deviant foliar concentrations. However, litterdecomposition rates were generally evaluated as normal.     

Bill color, not badge size, indicates testosterone-related information in house sparrows

The honesty of ornamental signals of quality is often argued to be enforced via costs associated with testosterone. It is still poorly understood, however, how seasonal variation of testosterone within individuals is related to the timing and extent of ornament development. Here, we studied inter- and intra-individual variability of plasma testosterone levels in a population of 150 captive male house sparrows (Passer domesticus) through the course of a full year. We further analyzed the relationship between plasma testosterone levels and two sexually dimorphic ornaments: badge size and bill coloration. Also, because of a known negative relation between molt and circulating testosterone levels, we analyzed the relationship between ornamentation and molt status during the fall. We found that testosterone levels increased towards the breeding season and decreased before the onset of annual molt. However, within individuals, relative testosterone titers demonstrated low repeatability between seasons. Plasma testosterone levels were not correlated with badge size in any season but were correlated strongly with bill coloration during all periods, except the breeding season when variation in bill color was low. Finally, we found that bill coloration strongly correlated with molt status during fall. Our results indicate that bill coloration, not badge size, is the best ornamental indicator of a “running average” of male testosterone in house sparrows and therefore the best potential indicator of qualities and/or behavioral strategies associated with testosterone.     

Decline in body size and female fraction in the grass snake (Natrix natrix,Linnaeus 1758) population after 40 years (Southern Poland)

Environmental Science and Pollution Research - Depletion of free-living populations is often associated with changes in fitness-related traits, e.g., body size. Ongoing decrease in body size has...