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Effect of experimental and seasonal warming on litter decomposition in a temper...
Ferreira, Verónica; Canhoto, C.Litter decomposition, a fundamental ecosystem process in woodland streams, is potentially affected by the predicted increase in water temperature. Here, we assessed the effects of experimental and seasonal warming on oak litter decomposition and on the relative contributions of microbes and invertebrates to this process. Experimental warming (*3 C) stimulated litter decomposition in the coldest, but not in the...
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 ...
Factors affecting decomposition of submerged litter and associated microbes and...
Ferreira, Verónica Jacinta LopesEsta tese está dividida em 6 capítulos onde foram estudados os efeitos de vários factores abióticos (i.e. velocidade da corrente, profundidade, nutrientes dissolvidos) e bióticos (i.e. presença de detritívoros, qualidade da folhada, composição da vegetação ribeirinha) na decomposição de material vegetal submerso e actividade biótica associada. A relevância deste tema prende-se com o facto da matéria orgânica fo...
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...
A predictive model for freshwater bioassessment (Mondego River, Portugal)
Feio, Maria; Reynoldson, Trefor; Ferreira, Verónica; Graça, ManuelAbstract We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model. At each site we also measured...
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 ...
Whole-stream nitrate addition affects litter decomposition and associated fungi...
Ferreira, Verónica; Gulis, Vladislav; Graça, ManuelAbstract We assessed the effect of whole-stream nitrate enrichment on decomposition of three substrates differing in nutrient quality (alder and oak leaves and balsa veneers) and associated fungi and invertebrates. During the 3-month nitrate enrichment of a headwater stream in central Portugal, litter was incubated in the reference site (mean NO3-N 82 µg l-1) and four enriched sites along the nitrate gradient ...
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