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The effect of temperature on leaf decomposition and diversity of associated aqu...
Gonçalves, Ana Lucia; Graça, Manuel A. S.; Canhoto, CristinaWe examine the relative importance of substrate quality and temperature in the establishment of aquatic hyphomycete assemblages and in their ability to decompose leaves. We used leaves of alder (Alnus glutinosa) and oak (Quercus robur) and we tested four temperatures (5 , 10 , 15 and 20 C). Differences in decomposition rates and fungal assemblages were higher substrata than across temperatures. In both speci...
Evaluation of stream ecological integrity using litter decomposition and benthi...
Castela, José; Ferreira, Verónica; Graça, Manuel A. S.Biomonitoring programs to access the ecological integrity of freshwaters tend to rely exclusively on structural parameters. Here we evaluated stream ecological integrity using (a) benthic macroinvertebrate derived metrics and a biotic index as measures of structural integrity and (b) oak litter decomposition and associated fungal sporulation rates as measures of functional integrity. The study was done at four ...
Leaf litter as a possible food source for chironomids (Diptera) in Brazilian an...
Callisto,Marcos; Gonçalves Jr,José F.; Graça,Manuel A. S.Our objective was to evaluate the potential use of leaf detritus by chironomid larvae. Field and laboratory experiments were performed using leaves and chironomid species collected in Portugal and Brazil. Laboratory experiments under controlled conditions were done using microbial conditioned senescent leaves of Alnus glutinosa (L.) Gaertn, Neriumoleander L., Protium heptaphilum (Aubl.) March, Protium brasilien...
Fungal Activity Associated with Decomposing Wood is Affected by Nitrogen Concen...
Ferreira, Verónica; Graça, Manuel A. S.We examined the effect of two contrasting nitrogen concentrations in water (0.16 and 0.82 mg L-1) in the mass loss of pre-conditioned balsa wood, and associated fungal activity, in a laboratory microcosm experiment. Contrary to our predictions given the poor nutrient quality of balsa wood, an increase in dissolved nitrogen concentration did not result in increased mass loss or microbial oxygen consumption. Coni...
Decomposition of Fire Exposed Eucalyptus Leaves in a Portuguese Lowland Stream
Gama, Mafalda; Gonçalves, Ana Lúcia; Ferreira, Verónica; Graça, Manuel A. S.; Canhoto, CristinaWe compared fire exposed with normal abscised eucalyptus leaves incubated in a stream running through eucalyptus plantations in central Portugal, in terms of breakdown rates, microbial activity, diversity and macroinvertebrate abundance. Although leaves exposed to fire had lower nutritional value, mass loss was similar for both leaf types (k = 0.0089-0.0095 d-1 for fire and k = 0.0084-0.00103 d-1 for normal lea...
Do Invertebrate Activity and Current Velocity Affect Fungal Assemblage Structur...
Ferreira, Verónica; Graça, Manuel A. S.In this study we assessed the effect of current velocity and shredder presence, manipulated in artificial channels, on the structure of the fungal assemblage colonizing alder (Alnus glutinosa (L.) Gaertner) leaves incubated in coarse and fine mesh bags. Fungal sporulation rates, cumulative conidial production and number of species of aquatic hyphomycetes were higher in leaves exposed to high rather than to low ...
Influence of Detritus on the Structure of the Invertebrate Community in a Small...
González, M.; Graça, Manuel A. S.This study tests if the coarse particulate organic matter (CPOM) mass was related to the invertebrate community structure in riffles and sandy pools of a fourth-order reach of a stream after partialling out the effects of physical characteristics of the sampled patches. Diversity and structure of the assemblages differed between habitats. In both, CPOM mass was positively correlated with total density and with ...
Degradation of Leaf Litter Phenolics by Aquatic and Terrestrial Isopods
Zimmer, Martin; Oliveira, Ricardo; Rodrigues, Elsa; Graça, Manuel A. S.To investigate species-specific decomposition rates of litter from native (Quercus faginea) and introduced (Eucalyptus globulus) tree species in Portugal, we monitored changes in the phenolic signature of leaf litter during decomposition as mediated by an aquatic, Proasellus coxalis (Isopoda: Asellota), and two terrestrial, Porcellio dispar and Eluma caelatum (Isopoda: Oniscidea), detritivores. Although the lit...
Factors Affecting Macroinvertebrate Richness and Diversity in Portuguese Stream...
Graça, Manuel A. S.; Pinto, Paulo; Cortes, Rui; Coimbra, Nuno; Oliveira, Simone; Morais, Manuela; Carvalho, Maria João; Malo, JorgeWe analysed the spatial patterns in macroinvertebrate taxon richness and abundance at two scales: sampling unit and basin. We sampled 12 stream sites in three zones of Portugal, differing in climate geomorphology and water chemistry. At a sampling unit scale, substratum organic matter content, depth and the dominant size of substratum particles were correlated with numbers of taxa and individuals. We propose th...
In situ tests for water quality assessment: a case study in Pampean rivers
Graça, Manuel A. S.; Rodrígues-Capítulo, Alberto; Ocón, Carolina; Gómez, NoraTwo invertebrate species (Hyalella curvispina and Palaemonetes argentinus) and one macrophyte (Egeria densa) from a naturally high nutrient content system (Pampean rivers of La Plata, Argentina) were evaluated for their potential use in situ assays aiming to assess changes in water quality. Invertebrates were individually placed in cylindrical chambers in polluted sections of rivers and in reference upstream si...
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