Centro Universitario Leonardo da Vinci
Centro Universitario Leonardo da Vinci
Ebert L.A.,Centro Universitario Leonardo da Vinci |
Ebert L.A.,Federal University of São Carlos |
Branco J.O.,Vale do Itajai University |
Barbieri E.,Institute Pesca Of Sao Paulo
Pan-American Journal of Aquatic Sciences | Year: 2014
The gull Larus dominicanus is one of the most common coastal seabirds of the Brazilian coast, being capable of using several habitats and types of preys. In that context the estuary of Saco da Fazenda is an important feeding area, bathing, cleaning of the feathers and resting. The objective of this work was evaluating the population structure and daily activity of L. dominicanus in the estuary. From February/2004 to January/2005, the gulls were monitored in monthly census in the Saco da Fazenda, with intervals of two hours among the census from the 6:00 am to 8:00 pm. The oscillations observed in the population of L. dominicanus along the year were considered significant, being higher in autumn. The occupation of the estuary started from the first hours of the day, culminating at the 2:00 pm. In the morning, the gulls were observed in feeding activity, following by the bathing, cleaning of the feathers and resting. In the afternoon the abundance reduced significantly, with the dispersion of the gulls to close areas to the Saco da Fazenda. The oscillations found in the abundance of L. dominicanus during this study can be attributed to events of the cycle of life of the gulls and the differences observed in the number of gulls along the day to the period of activity of the fishing fleet.
De Paula A.,State University of Southwest Bahia |
Martins F.Q.,Centro Universitario Leonardo da Vinci |
Batalha M.A.P.L.,Federal University of São Carlos |
Rodrigues R.,Federal University of São Carlos |
Manhaes M.A.,Federal University of Juiz de fora
Ciencia Florestal | Year: 2015
The capacity of ‘cerrado’ species to regrow from underground organs after deforestation depends on the soil physical and chemical properties and the time elapsed since the disturbance. In Itirapina Ecological Station, we carried out floristic and phytosociological surveys of both herbaceous and woody components of the vegetation in ‘cerrado’ in a regenerating plot, after two years of Pinus elliotti removal, and in a neighboring preserved the ‘cerrado’ area. In each of the two areas have been launched along a transection, 20 parts of 5 m x 5 m, systematically distributed to each 20 m. These plots were sampled the woody component (all woody plants with stem diameter at ground level equal to or greater than 3 cm). In each of the plots was defined a sub-portion of 0.5 m x 0.5 m, which was sampled at the herbaceous component (all woody plants with a stem diameter at the ground level lower than 3 cm and all non-woody). The lowest diversity index was found for the herbaceous component of the regeneration area (1.29 nats.individual-1), while the highest was for the herbaceous component of the preserved area of ‘cerrado’ (2.75 nats. individual-1). Among the areas being regenerated and preserved, Sørensen’s similarity indices for both the herbaceous component (0.23) and for the woody component (0.31), showed low floristic similarity between areas. Besides, the density and richness for both components were significantly higher for the area preserved in ‘cerrado’. The results showed that the two years elapsed since Pinus elliotti clear-cut were not enough for the natural vegetation recovery. © 2015, Universidade Federal de Santa Maria. All rights reserved.
Correa C.E.,Centro Universitario Leonardo da Vinci |
Albrecht M.P.,Federal University of Rio de Janeiro |
Hahn N.S.,State University of Maringá
Neotropical Ichthyology | Year: 2011
Spatial and temporal variations in patterns of niche breadth and feeding overlap were investigated for the fish fauna in the Pantanal region, aiming to determine the factors that account for species coexistence. Samples were conducted in the Cuiabá River and Chacororé pond, in the upper Pantanal region, Mato Grosso State, Brazil, during one hydrological cycle (March 2000 to February 2001), (designed spatial-seasonal units). Mean niche breadth values were overall low for the fish assemblage (0.2- 0.3). Differences between periods were not statistically significant. Feeding overlap values ranged between 0 and 0.4, whereas the mean was always inferior to 0.05 in all spatial-temporal units, and differences between periods were not statistically significant. The highest and lowest mean values were both observed in the pond; the former during the drought period and the latter during the flood period. All feeding overlap mean values were significantly higher than the values expected at random in the null model, using both "scrambled-zeros" (RA3) and "conserved-zeros" (RA4) algorithms. Thus, the foraging patterns show evidences of food sharing. The variance generated in the null model had a pattern similar to the niche overlap pattern: observed variance was higher than expected by chance in all spatial-temporal units, suggesting that the fish fauna is structured in trophic guilds. The patterns of food resource use and the different trophic guilds identified, suggest that species probably have different roles in this ecosystem. Our results suggest that food sharing allows coexistence of different fish species. © 2011 Sociedade Brasileira de Ictiologia.
Edelaar P.,CSIC - Doñana Biological Station |
Donazar J.,CSIC - Doñana Biological Station |
Soriano M.,Estacion Cientifica de Bahia Bustamante |
Santillan M.A.,National University of La Pampa |
And 14 more authors.
Evolutionary Ecology Research | Year: 2011
Background: Southern caracaras are medium-sized raptors with a large range stretching to the southern tip of South America. An aberrant, leucistic plumage is found commonly along the coast of Chubut Province (Patagonia, Argentina). Leucistic birds do not produce dark melanin in their feathers. However, they are not albinos because their eyes are not red. No genetic studies of caracara plumages are known. Hypothesis: The high frequency of leucistic birds in Chubut Province arises because of natural selection. Methods: Map the distribution of leucistic individuals relative to normal individuals. Combine a variety of anecdotal natural history observations, collected over 20 years, into a logical inference. Observations: Leucistic caracaras were found only along a 250-km stretch of rocky oceanic islands and continental outcrops with large seabird colonies in Chubut Province. In the rest of their range, Southern caracaras have dark plumage. Where they do occur, leucistic birds are frequent and co-occur with dark-plumaged birds. Intermediate individuals, presumably. heterozygotes, exist. Leucism is not related to age or sex. Leucistic individuals are restricted to a particular habitat. Gene flow has not homogenized the coastal and inland populations. Results: Leucism is not simply due to inbreeding producing more homozygous individuals. Leucism is not due to genetic drift. Leucism is not an environmental effect on individual physiology or development. Leucism is not a transient (plastic) phenomenon. Where they occur frequently, leucistic Southern caracaras are apparently favoured by natural selection, either directly or by pleiotropy. © 2011 Pim Edelaar.
Tontini G.,Federal University of Santa Catarina |
Dalla Lana Semione G.,Federal University of Santa Catarina |
Bernardi C.,Centro Universitario Leonardo da Vinci |
Binder R.,Whirlpool Do Brazil |
And 2 more authors.
Industrial Lubrication and Tribology | Year: 2016
Purpose - This paper aims to synthesize nanostructured flower-like molybdenum disulphide (MoS2) particles and evaluate their suitability to act as additives for lubricants. Design/methodology/approach - A hydrothermal method without any surfactant successfully produced 250 nm mean diameter Nanostructured flower-like MoS2 particles. The resulting product was then solvothermally treated with absolute ethanol producing lipophilic powder particles which after being dispersed in two different lubricants were tribologicaly characterized by using a pin-on-disk tribometer geometry with reciprocal movement under immersion. Findings - The influence on the stability and the coefficient of friction of the nano-oils is shown to be strongly dependent on their molecular structure. After 1 h of tribological testing, a ramified polyolester oil with 1 Wt.% of MoS2 nanoflowers did not show decrease in its average coefficient of friction, while an additive naphthenic oil with the same concentration of nanoparticles showed a decrease of 86 per cent. Originality/value - In this paper, nanostructured flower-like MoS2 synthesized by the hydrothermal method was dispersed in lubricating oils to study its stability and tribological properties. To ensure good stability of the nano-oils, the particles were solvothermally treated with absolute ethanol to dehydrate and lipophilize them. A ramified polyolester-based nano-oil with 1 Wt.% of MoS2 nanoflowers showed no decrease in its steady state coefficient of friction, while a naphthenic-based nano-oil with the same concentration of nanoparticles presented a remarkable 86 per cent reduction. © Emerald Group Publishing Limited.