Bus fleet emissions: new strategies for mitigation by adopting natural gas

Energy consumption is related to local, regional and global impacts. Thus, by comparing different replacement scenarios of diesel vehicles with compressed natural gas, this article estimates pollutants and greenhouse gases emission in the city of São Paulo, Brazil. The calculation of fuel consumption is based on fleet characteristics, in terms of vehicle age, the average annual distance travelled by bus depending on the year and average fuel consumption. These values served as a basis to develop scenarios considering that a percentage of new vehicles that will be phased out and replaced with ones running on natural gas. Results show that the total avoided emissions can range from 579 thousand tons to 1.375 million tons of carbon dioxide (CO₂₎ over 20 years, depending on the scenario. For particulate matter, accumulated avoided emissions vary from 251 thousand to 584 tons over 20 years. The replacement of diesel buses with natural gas-fuelled buses presents favourable results, in comparison with the tendency scenario for CO₂ and particulate matter. Thus, a public policy for fuel replacement in largest cities, such as Sao Paulo, has an important global impact, especially when allowing the introduction of a renewable energy source, such as biogas. It will benefit from the natural gas previous infrastructure, which is largely available in Brazil. As recommendations, we explain the need to review the city of Sao Paulo Climate Change Law to allow the use of natural gas. Fuel replacement should be integrated with a public policy/public policies and operational strategies to promote citizens´ health as well as historical, cultural and heritage conservation for the city and its future generations.     

Communal nesting and kinship in degus (<Emphasis Type="Italic">Octodon degus</Emphasis>)

Communal nesting is a fundamental component of many animal societies. Because the fitness consequences of this behavior vary with the relatedness among nest mates, understanding the kin structure of communally nesting groups is critical to understanding why such groups form. Observations of captive degus (Octodon degus) indicate that multiple females nest together, even when supplied with several nest boxes. To determine whether free-living degus also engage in communal nesting, we used radiotelemetry to monitor spatial relationships among adult females in a population of O. degus in central Chile. These analyses revealed that females formed stable associations of > 2–4 individuals, all of whom shared the same nest site at night. During the daytime, spatial overlap and frequency of social interactions were greatest among co-nesting females, suggesting that nesting associations represent distinct social units. To assess kinship among co-nesting females, we examined genotypic variation in our study animals at six microsatellite loci. These analyses indicated that mean pairwise relatedness among members of a nesting association (r=0.25) was significantly greater than that among randomly selected females (r=–0.03). Thus, communally nesting groups of degus are composed of female kin, making it possible for indirect as well as direct fitness benefits to contribute to sociality in this species.     

Geostatistical analysis of densities of Liocarcinus depurator (Brachyura: Portunidae) on the western Mediterranean from 1994 to 2003

Bottom trawl estimates of densities of the portunid crab Liocarcinus depurator along the Mediterranean coast of Spain from 1994 to 2003, covering a depth range of 50–800 m, were analysed using non-linear geostatistical techniques. The variation of the spatial distribution was modelled through variogram analysis using depth as a covariate. Patch size ranged from 20 to 75 km. Crab density showed a general decrease from 1994 to 2003. L. depurator high-density areas were characterised as either occasional or permanent (always present every year). High-density patches appeared to be associated with either upwelling or strong river influence, i.e. the Western Alborán Sea and the Ebro Delta. The application of non-linear geostatistical techniques proved useful in identifying permanent high-density population patches, thereby highlighting regions of special interest for the ecology of the species.     

Is obligate siblicidal aggression food sensitive?

In avian species whose chicks show facultative siblicide, attacks increase with food deprivation. In species that show obligate siblicide, this causal relationship is not expected, but no test has been made. When we composed artificial pairs of young brown boobies, Sula leucogaster (an obligately siblicidal species), and supplied variable amounts of food to the older nestlings in each pair, food ingestion was related to the most intense form of attack, pushes, which can cause death by expelling the broodmate from the nest. The less food an older nestling ingested, the more time it spent active and the greater its rate and absolute frequency of pushes, and the more often it expelled its nestmate. Hence, deficient food provision to older nestlings could precipitate siblicidal expulsion of broodmates. Younger nestmates were aggressive too, and the more they were pushed and expelled, the more they pecked. Aggression of senior brown-booby broodmates may be flexible and food sensitive in order to optimize the timing of siblicide or to make siblicide weakly facultative.Communicated by R. Gibson     

安第斯山脉地下水中稀有鲶鱼种族面临灭绝风险及对其保护的重要性

相对于数量和品种都更为繁多的岩洞鱼类而言,地下水中的鱼类在世界上任何地方都较为稀少.这部分原因可能是由于知识的不完整,这是这些鱼类的生活环境极难为人类所探测的后果(Femandez和de Pinna,未发表资料).一般情况下在这种环境中对鱼的采样都是间接完成的,通过在天然水库或者自然水洞中投放诱捕器或者是从井中拉网捕鱼.Proudlove[1]"综合分析了地下水中鱼类的自然保护状态,发现这些鱼主要易受5种因素影响:生活环境恶化,水文条件人为变动,环境污染,过度捕捞,及外来品种入侵.由于这些鱼生活在较小的区域,而且数量较少,因此任何危害都会产生严重后果.一些种类已经受到关注和保护,而大部分却没有.     

Distribution of metals in mechanical fractions of soils from a lake catchment in Venezuela

Soil samples were collected from both the surface and at depth from the lowlands around Lake Valencia and from the adjacent mountains. This paper reports results for Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn in mechanical fractions of the soils. Lowland soils, developed on lacustrine sediments, show a predominance of medium- to fine-grain size fractions whereas the shallow mountain soils show the highest percentage of particles in the coarse to medium fractions. Concentrations of most of the elements investigated increased toward finer particle sizes. The generally higher metal concentrations in lowland soils compared with mountain soils are consistent with release by weathering in the uplands and accumulation in the lowlands. The presence of carbonates derived from ubiquitous shelly material in the lowland soils may explain increases of Ca and Mg in labile fractions. In the lowland area, there is little evidence for the translocation of metals in the soil profiles, despite the high rainfall of a tropical climate, and the calcareous nature of these soils could account for the immobility of metals.     

The function of hatching asynchrony in the blue-footed booby

The blue-footed booby (Sula nebouxii) commonly hatches two eggs 4 days apart; then the senior (first-hatched) chick aggressively dominates the other and sometimes kills it. Two hypotheses explaining the function of the hatching interval were tested by creating broods with synchronous hatching: the facultative brood reduction hypothesis of Lack (1954) and the sibling rivalry reduction hypothesis of Hahn (1981). The results contradicted most predictions of both hypotheses: synchronous broods formed an aggressive hierarchy similarly to asynchronous broods (controls), and subordinate chicks grew poorly (Fig. 1) and died frequently, similarly to junior chicks in control broods. However, compared with synchronous broods, asynchronous broods showed less aggression (Fig. 2), diminished food allocation to subordinate chicks (Fig. 3) and less total food consumption (30% fewer feeds at age 0–10 days). These behavioral comparisons took into account the different ages of chicks in different treatments. The results suggest that natural asynchrony makes brood reduction more efficient and decreases the costs of sibling aggression to parents, in terms of their future survival or fecundity, as proposed by Mock and Ploger (1987). Further, in exaggeratedly asynchronous broods (8-day hatch interval) junior chicks suffered more aggression (Fig. 4) and grew more slowly than junior chicks in control broods. This result supports the hypothesis of optimal hatch asynchrony of Mock and Ploger (1987).     

New Early Cretaceous fossil from China documents a novel trophic specialization for Mesozoic birds

We report on a new Mesozoic bird, Longirostravis hani, from the Early Cretaceous Jehol Biota of northeastern China. The new taxon has a long, slender rostrum and mandible, and a small number of rostralmost teeth. Postcranial characters such as a furcular ramus wider ventrally than dorsally, a centrally concave proximal margin of the humeral head, and a minor metacarpal that projects distally more than the major metacarpal, support the placement of Longirostravis within euenantiornithine Enantiornithes, the most diverse clade of Mesozoic birds. The morphology of the skull, however, suggests that Longirostravis had a probing feeding behavior, a specialization previously unknown for Enantiornithes. Indeed, this discovery provides the first evidence in support of the existence of such a foraging behavior among basal lineages of Mesozoic birds.     

A pest is a pest is a pest? The dilemma of neotropical leaf-cutting ants: Keystone taxa of natural ecosystems

Leaf-cutting ants of the generaAcromyrmex andAtta are considered the principal polyphagous pests of the Neotropics Although some members of these genera are of economic importance, have a broad geographic distribution, and are extremely good colonizers, others are endemic and closely interact with native ecosystems. Control is generally practiced against any colony, irrespective of its taxonomic status. Indiscriminate control coupled with habitat destruction threatens endemic species with extinction, and, through habitat simplification, favors other pest species. As nests ofAtta are large, having several square meters of nest surface, the endemic taxa can be easily used as environmental indicators for natural ecosystems Likewise, the pest species can be used to detect environmental disturbance As these ants are keystone species and easily identified by nonspecialists, efforts should be made to integrate these into viable conservation programs