673 resultados para south-western Victoria
Resumo:
Background, aim and scope Soil organic matter (SOM) is known to increase with time as landscapes recover after a major disturbance; however, little is known about the evolution of the chemistry of SOM in reconstructed ecosystems. In this study, we assessed the development of SOM chemistry in a chronosequence (space for time substitution) of restored Jarrah forest sites in Western Australia. Materials and methods Replicated samples were taken at the surface of the mineral soil as well as deeper in the profile at sites of 1, 3, 6, 9, 12, and 17 years of age. A molecular approach was developed to distinguish and quantify numerous individual compounds in SOM. This used accelerated solvent extraction in conjunction with gas chromatography mass spectrometry. A novel multivariate statistical approach was used to assess changes in accelerated solvent extraction (ASE)-gas chromatography-mass spectrometry (GCMS) spectra. This enabled us to track SOM developmental trajectories with restoration time. Results Results showed total carbon concentrations approached that of native forests soils by 17 years of restoration. Using the relate protocol in PRIMER, we demonstrated an overall linear relationship with site age at both depths, indicating that changes in SOM chemistry were occurring. Conclusions The surface soils were seen to approach native molecular compositions while the deeper soil retained a more stable chemical signature, suggesting litter from the developing diverse plant community has altered SOM near the surface. Our new approach for assessing SOM development, combining ASE-GCMS with illuminating multivariate statistical analysis, holds great promise to more fully develop ASE for the characterisation of SOM.
Resumo:
Soil organic matter (SOM) increases with time as landscape is restored. Studying SOM development along restored forest chronosequences would be useful in clarifying some of the uncertainties in quantifying C turnover rates with respect to forest clearance and ensuing restoration. The development of soil organic matter in the mineral soils was studied at four depths in a 16-year-old restored jarrah forest chronosequence. The size-separated SOM fractionation along with δ13C isotopic shift was utilised to resolve the soil C temporal and spatial changes with developing vegetation. The restored forest chronosequence revealed several important insights into how soil C is developing with age. Litter accumulation outpaced the native forest levels in 12 years after restoration. The surface soils, in general, showed increase in total C with age, but this trend was not clearly observed at lower depths. C accumulation was observed with increasing restoration age in all three SOM size-fractions in the surface 0–2 cm depth. These biodiverse forests show a trend towards accumulating C in recalcitrant stable forms, but only in the surface 0–2 cm mineral soil. A significant reverse trend was observed for the moderately labile SOM fraction for lower depths with increasing restoration age. Correlating the soil δ13C with total C concentration revealed the re-establishment of the isotopically depleted labile to enriched refractory C continuum with soil depth for the older restored sites. This implied that from a pedogenic perspective, the restored soils are developing towards the original native soil carbon profile.
Resumo:
This paper reports the first well-documented specimen of the goblin shark, Mitsukurina owstoni in the south-western Atlantic, based on a mature male measuring 3152 mm total length, caught on 27 November 2008 off the Rio de Janeiro coast, south-east Brazil.
Resumo:
This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado) of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites) and frequencies of species killed by cars on roads. Sites (n = 80) within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23) were searched for records of mammals. Species surveyed in the entire region totaled 33, belonging to nine orders and 16 families. In the Cerrado, 31 species were recorded in habitats; of these, 25 were found dead on roads. In the Atlantic Forest ecoregions, however, we found 21 species in habitats, 16 of which were also found dead on roads. There was no overall significant difference between ecoregions for frequencies of occurrence in habitats or for roadkills, but there were differences between individual species. Hence, anteaters were mostly recorded in the Cerrado ecoregion, whereas caviomorph rodents tended to be more frequent in the Atlantic Forest ecoregion (seen mainly by roadkills). The greater number of species (overall and threatened) and the greater abundance of species records in the Cerrado suggest that this ecoregion has a greater biodiversity and is better conserved than the Atlantic Forest ecoregion, in the state of Mato Grosso do Sul, south-western Brazil.
Resumo:
The population structure and reproductive biology of Mustelus schmitti was analysed during autumn (1994, 1995) and spring (1994) in the Rio dc la Plata occanic front. The samples consisted mainly of a adult males and immature females, indicating that nursery areas are Situated elsewhere. In autumn, the highest female densities occurred between 36 degrees S and 35 degrees S, with densities decreasing further south, and high male densities occurred over all latitudes of the study area. In Spring, both Sexes occurred north of latitude 36 degrees 30 degrees S. Males attained Maturity at. 59 cm total length (TL), and females at 72 cmTL Litter size varied From one to ten in spring and two to nine in autumn, With embryos ranging from 9 to 26 cm and 7 to 26 cm TL respcctivcly the mean TL of embryos was significantly higher in spring (22 cm), suggesting that parturition Occurs ill late spring and summer. Litter size was found to Increase with female TL..
Resumo:
The ovarian complement of anurans exhibiting different reproductive modes is highly diverse, and intraspecific variation in reproductive output of anurans is generally related to variation in female properties and/or environmental conditions. The size-fecundity relationships, reproductive investment, and correlation between ovary mass and fat body mass were investigated for females of an anuran assemblage in the Pantanal, Brazil. Female body size was positively correlated with clutch size among seven of the eight species analyzed. However, these results seem to be influenced by seasonal variation in fecundity. Interspecific size-fecundity relationships revealed that female SVL was positively correlated with clutch size and egg size regardless of reproductive mode. Among 11 species analyzed, the reproductive investment (RI: ovary mass relative to body mass) varied from 5.5 to 18%, and there were no differences among reproductive modes and activity patterns (explosive/prolonged). RI correlated negatively with female size. Among three Leptodactylus species examined, negative correlation between ovary mass and fat body mass was verified for two species. Variations in the reproductive strategies are closely related to the reproductive activity patterns and reproductive modes exhibited by individual species, but are also influenced by environmental conditions. However, regardless of reproductive mode or activity pattern, each species seems to exhibit a reproductive strategy that allows them to respond differently to the same environmental restrictions.
Resumo:
Some crustaceans show variations of their reproductive biology within their geographical distribution, and knowledge about such variations is important for the comprehension of their reproductive adaptations. This study compared two populations of the fiddler crab Uca uruguayensis from two locations on the south-western Atlantic coast: Ubatuba Bay, São Paulo, Brazil and Samborombón Bay, Buenos Aires, Argentina. The population features analysed were the body size variation (carapace width = CW) and the size at the onset of sexual maturity (SOM) in order to test the hypothesis that the size at SOM, should be the same in relative terms (RSOM), independently of the latitudinal position. In the Brazilian population the CW ranged from 4.18 to 11.60 mm for males and 3.90 to 9.80 mm for females, and in the Argentinean population from 3.60 to 14.10 mm for males and 2.85 to 12.00 mm for females. In the Brazilian population the SOM was 7.1 (RSOM = 0.58) and 5.9 mm CW (RSOM = 0.57) for males and females, respectively, and in the Argentinean population it was 7.0 (RSOM = 0.42) and 6.75 mm CW (RSOM = 0.53) for males and females, respectively. This fact is probably related to a great plasticity in the life history features of Uca uruguayensis under different environmental conditions. © 2012 Marine Biological Association of the United Kingdom.
Resumo:
Neurocrania of three species of angelsharks from the south-western Atlantic Ocean, occurring off south-eastern and southern Brazil, are described. A detailed morphological description is provided of the neurocranium of Squatina guggenheim and compared with S. argentina and S. occulta. Despite being generally conservative, the neurocranium of Squatina presents significant differences among these species which aid in their identification, which is otherwise problematical. The main distinctions were found in rostral projections, anterior fontanellae, supraorbital crests, upper and lower postorbital processes, otic capsules, suborbital crests, and pterotic processes. Squatina guggenheim and S. occulta share more neurocranial characters when compared to S. argentina. No basal angle was found, but we confirm the presence of a very much reduced and barely noticeable basioccipital fovea in Squatina; systematic implications within elasmobranchs of these and other features are discussed.
Resumo:
In this paper, we present the results of an experimental approach developed to study the macroscopic and microbiological alteration of bird and small mammal bones buried under a Cerrado biome. The first experiment evaluated the macroscopic alteration of cooked and fresh carcasses buried through the dry and rainy seasons. The second experiment analyzed the mycobiota associated to the decomposition of a complete bird that remained buried for almost a year. Results show that in tropical forest environments: 1) bone structure and pre-taphonomic factors determine its differential alteration by biochemical processes; 2) fungal populations associated to the decomposition of animal remains depend on soil chemistry and ecological dynamics; 3) even in a corrosive environment, bird bones are more capable of surviving to several mycological decomposition steps. (C) 2011 Elsevier Ltd. All rights reserved.
Resumo:
Universidad de Las Palmas de Gran Canaria. Facultad de Ciencias del Mar. Trabajo Fin de Título para la obtención del Graduado en Ciencias del Mar, 2013-2014
Resumo:
Since 1900, the Yoruba people of South-western Nigeria have put its ethnic history at work in the construction of its identity in Nigeria. The exercise resulted in the creation of ethno-nationalist movements and the practice of ethnic politics, often expressed through violent attacks on the Nigerian State and some ethnic groups in Nigeria. Relying on mythological attachment to its traditions and subjective creation of cultural pride, the people created a sense of history that established a common interest among different Yoruba sub-groups in form of pan-Yoruba interest which forms the basis for the people’s imagination of nation. Through this, historical consciousness and socio-political space in which Yoruba people are located acted as instrumental forces employed by Yoruba political elites, both at colonial and post-colonial periods to demand for increasing access to political and economic resources in Nigeria. In form of nationalism, nationalist movements and ethnic politics continued in South-western Nigeria since 1900, yet without resulting to actual creation of an independent Yoruba State up to 2009. Through ethnographic data, the part played by history, tradition and modernity is examined in this paper. While it is concluded that ethno-nationalist movement and ethnic politics in Yoruba society are constructive agenda dated back to pre-colonial period, it continues to transform both in structure and function. Thus, Yoruba ethno-nationalist movement and ethnic politics is ambiguous, dynamic and complex, to the extent that it remains a challenge to State actions in Nigeria.