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Kunert N.,Max Planck Institute for Biogeochemistry | Kunert N.,Brazilian National Institute for Research in the Amazon | Edinger J.,Max Planck Institute for Biogeochemistry
Biotropica | Year: 2015

The relationship between sap flux and stem CO2 efflux was assessed for three mango trees. We observed higher than expected CO2 effluxes at the place of measurement under intermediate sap flux velocities and lower fluxes under high sap flux velocity. This variation disappeared after removing the tree crown. © 2015 Association for Tropical Biology and Conservation Inc.


Kochhann D.,Brazilian National Institute for Research in the Amazon | Val A.L.,Brazilian National Institute for Research in the Amazon
Hydrobiologia | Year: 2016

Differences in aggressiveness when competing for environmental resources are the main factor leading to social hierarchy in group living fish. Social status acquired is related to changes in physiological parameters, as metabolic rate. Habitat variation can interfere with aggressive behaviour and promote changes in physiological parameters associated with social status. The primary goal of our study was to investigate how differences in habitat complexity affect the relationship between resting metabolic rate (RMR) and social status in the Amazonian dwarf cichlid Apistogramma agassizii. We compared agonistic interactions between pairs of males in aquaria with different habitat enrichment levels, manipulated by adding shelters. RMR was measured before and after hierarchy establishment. Habitat enrichment promotes changes in aggressive behaviour and influences differences in metabolic rate between dominant and subordinate fish. We observed an increase in biting by dominant fish at high enrichment habitat, which could be related to the increase in territory value. We observed an increase in metabolic rate in dominant fish after hierarchy establishment. However, it occurs only in enriched habitats. We concluded that habitat structure interfere with behavioural characteristics in social hierarchies, as aggressiveness, and changes in aggressive interactions affect metabolic rate in different social ranks in the dwarf cichlid Apistogramma agassizii. © 2016 Springer International Publishing Switzerland


Da Silva F.,Brazilian National Institute for Research in the Amazon | Suwa R.,Japan Forestry and Forest Products Research Institute | Kajimoto T.,Japan Forestry and Forest Products Research Institute | Ishizuka M.,Japan Forestry and Forest Products Research Institute | And 3 more authors.
Forests | Year: 2015

Allometric models to estimate biomass components such as stem mass Ms, foliage mass Ml, root mass Mr and aboveground mass Ma, were developed for the palm species Euterpe precatoria Mart., which is the most abundant tree species in the Amazon. We harvested twenty palms including above- and below-ground parts in an old growth Amazonian forest in Brazil. The diameter at breast height D ranged from 3.9-12.7 cm, and the stem height H ranged from 2.3-16.4 m. The D, diameter at ground basis D0, crown diameter CD, H, stem specific gravity ρ, and number of fronds Nf were considered as independent variables and incorporated into a power function model. The best predictors were D2Hρ for Ms and Ma, D2HNf for Ml, and D for Mr. Slender index (H/D) ranged from 0.56-1.46 m.cm-1, and the D-H relationship suggested that the stem shape becomes more slender with increasing D. On the other hand, ρ increased with D implying a stiffening of stem tissue. The average root/shoot ratio was estimated as 0.29 which was higher than that reported for the non-palm tree species in the Amazon. Comparisons of several models to estimate Ma of different palm species, suggested that the variations of the D-H relationship and ρ should be considered to develop allometric models for estimating biomass in palm species. In particular the ρ largely varied depending on individual size, which should be important to consider, when developing the allometric models for palms. © 2015 by the authors; licensee MDPI, Basel, Switzerland.


Kunert N.,Max Planck Institute for Biogeochemistry | Kunert N.,Brazilian National Institute for Research in the Amazon | Aparecido L.M.T.,Brazilian National Institute for Research in the Amazon | Aparecido L.M.T.,Texas A&M University | And 3 more authors.
Agricultural and Forest Meteorology | Year: 2015

Newly created forest edges have significant ecophysiological effects on bordering trees. We studied edge effects on microclimate and tree transpiration rates during wet and dry seasons along a 250. m transect spanning the edge of an unpaved road into an old growth tropical lowland forest in the Central Brazilian Amazon. Canopy openness decreased only minimal from the road (3.68%) towards the forest interior (1.69%). Vapor pressure deficit (measured at 2.2. m height above ground) was lower in the forest interior. The edge effect on microclimate penetrated deeper into the forest (>100. m) during the dry season compared to the wet season (<100. m). Overall, sap flux, and therefore transpiration rate, was 54% higher in trees adjacent to the road compared to forest interior trees. Higher transpiration rates at the forest edge can be explained by higher turbulences and energy exchange of the canopy boundary layer and by a shift in species composition to high water using secondary forest species 25 years after the road construction. Similar changes might be expected for other disturbances affecting local relative humidity and in situations that favor plants with water use traits differing from those found in the forest interior. © 2015 Elsevier B.V.


Sadauskas-Henrique H.,Brazilian National Institute for Research in the Amazon | Braz-Mota S.,Brazilian National Institute for Research in the Amazon | Duarte R.M.,Brazilian National Institute for Research in the Amazon | Duarte R.M.,Sao Paulo State University | de Almeida-Val V.M.F.,Brazilian National Institute for Research in the Amazon
Environmental Science and Pollution Research | Year: 2016

The increment in crude oil exploitation over the last decades has considerably increased the risk of polycyclic aromatic hydrocarbon (PAH) contamination to Amazonian aquatic environments, especially for the black water environments such as the Rio Negro. The present work was designed to evaluate the acute toxicity of the Urucu crude oil (CO), the chemically dispersed Urucu crude oil (CO + D), and the dispersant alone (D) to the Amazonian fish Colossoma macropomum. Acute toxicity tests were performed, using a more realistic approach, where fish were acclimated to both groundwater (GW), used as internal control, and natural Rio Negro water (RNW) and exposed to CO, CO + D and D. Then, biomarkers such as ethoxyresorufin-O-deethylase (EROD), superoxide dismutase (SOD), lipid peroxidation (LPO), serum sorbitol dehydrogenase (s-SDH) in liver, DNA damage in blood cells, and the presence of the benzo[a]pyrene-type, pyrene-type, and naphthalene-type metabolites in fish bile were assessed. Fish exposed to CO and CO + D, at both water types tested, presented increased biomarker responses and higher PAH-type metabolites in the bile. However, fish exposed to these treatments after the acclimation to RNW increased the levels of LPO, s-SDH (hepatotoxicity), DNA damage in blood cells (genotoxicity), and benzo[a]pyrene-type metabolites when compared to fish in GW. Our data suggests that some physicochemical properties of Rio Negro water (i.e., presence of natural organic matter (NOM)) might cause mild chemical stress responses in fish, which can make it more susceptible to oxidative stress following exposure to crude oil, particularly to those chemically dispersed. © 2016 Springer-Verlag Berlin Heidelberg

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