This study evaluated if there are differences in leaf breakdown and invertebrate colonization amo... more This study evaluated if there are differences in leaf breakdown and invertebrate colonization among tree species differing in quality (toughness), and which factors could influence these differences. Com-mon alder leaves decomposed significantly faster then either sweet chestnut or Spanish oak (k values of – 0.0332, – 0.0108, and – 0.0112, respectively) during the first 2 months. Shredder abundance was high-est when leaf mass remaining was 50%, and the samples clustered in mixed groups of sampling dates and leaf species, suggesting that stage of decomposition was an important factor influencing shredder colonization. During the first two months of decomposition, the physicochemical characteristics of leaf litter and the interaction between leaf toughness and the occurrence of frequent spates seemed to be the main factors affecting leaf breakdown rates in the stream. 1.
This study assessed the effect of nutrient enrichment on rates of decomposition, ergosterol conce... more This study assessed the effect of nutrient enrichment on rates of decomposition, ergosterol concentrations (as a measure of fungal biomass), and rates of fungal sporulation of sweet chestnut (Castanea sativaMiller) leaves in a 3rd order stream (Central Portugal), with medium to high background values of nutrients. Coarse and fine mesh leaf bags were attached to nutrient diffusing substrata containing NaNO3, KH2PO4, both nutrients, or no additions. Leaf breakdown rates were similar in the four treatments and in the two mesh sizes (k=)0.0155 to)0.0219 day)1). Phosphorus content of P or N+P enriched leaves was higher than in the other treatments after 28 days, but there were no differences in N concentrations. Ergosterol concentrations associated with decomposing leaves were similar among treatments. The peak sporulation rates of aquatic hyphomycetes were stimulated by the addition of N+P and N but not by P alone. Results from the experiment provide evidence that leaf breakdown in the ...
Structure and diversity of the benthic macroinvertcbrate fauna were st~tdied in two deciduous for... more Structure and diversity of the benthic macroinvertcbrate fauna were st~tdied in two deciduous forest streams in Central Portugal. In the three sampling occasions. 120 tax-cl were collected from the two streams. Number of tci,xci per sampling occasion ranged from 53 to 60. Macroinvertebrate densities ranged from 1465 to 2365. Insects were the most abundant taxonomic group (280?h) in all samples. Detritivorous invertebrates were numerically dominant in both streams, representing 62 to 85 5 % of the total macroinvertebratc community.
ATP has been widely used to estimate total microbial biomass in a variety of systems (Karl 1980, ... more ATP has been widely used to estimate total microbial biomass in a variety of systems (Karl 1980, Maltby 1992, Gessner 1997, Abelho 2001). The ubiquitous distribution of ATP in living cells, the rapid loss from dead cells, the fairly constant concentrations in microorganisms (Holm-Hansen & Karl 1978), and the ease of
The role of carbon, nitrogen, and phosphorus in leaf decomposition mediated by aquatic fungi The ... more The role of carbon, nitrogen, and phosphorus in leaf decomposition mediated by aquatic fungi The aquatic microbial decomposition of leaf litter has been the subject of many field studies throughout the world. However, field experiments cannot always separate the effects of the multiple biotic and abiotic factors involved in the process. In this laboratory experiment, we controlled the abiotic factors and the fungal decomposer community during decomposition of alder, oak and eucalypt leaf litter in order to determine if variation in leaf carbon, nitrogen and phosphorus (CNP) ratios during decomposition was similar among the three species. Initial CNP values differed among the three species with alder being the richest (
Microorganisms play an important role as decomposers of plant litter in all environments. Various... more Microorganisms play an important role as decomposers of plant litter in all environments. Various approaches have been used to estimate their biomass in decomposing leaf litter, of which the quantification of ATP has been among the most popular, due to the ubiquitous distribution of ATP in living cells. This chapter describes a procedure to quantify ATP in decomposing leaf litter. The presented method involves cold acid extraction from leaves colonized by microorganisms, followed by quantification of ATP by luminometry using the firefly luciferin-luciferase reaction and internal ATP standards. The method has been successfully applied to quantify microbial biomass in a variety of environments. Where fungi dominate microbial biomass and the colonized plant tissue is dead, ATP can also be used to estimate fungal biomass as a rapid, easy, and relatively low-cost alternative to the quantification of ergosterol.
Respiration of heterotrophic organisms is an indicator of energy allocated to metabolism and henc... more Respiration of heterotrophic organisms is an indicator of energy allocated to metabolism and hence a general measure of biological activity. Therefore, respiration associated with plant litter can be used as an estimate of the functional significance of microbes in the decomposition process. This chapter describes procedures to measure respiration rates of both microbes and invertebrates in decomposing leaf litter. Respiration rates are determined by measuring oxygen consumption, either in closed or in open flow-through systems. The simplest closed system consists of a well-sealed water-filled flask without headspace, where oxygen concentrations are measured initially and again after a standard incubation period. More reliable estimates are obtained by continuously recording oxygen concentrations in respiration chambers equipped with oxygen electrodes. Alternatively, leaf samples or invertebrates are enclosed in flow-through chambers where respiration rate is determined as the diffe...
In this study we assessed the C : N : P ratios in soil and soil microbial biomass subject to conv... more In this study we assessed the C : N : P ratios in soil and soil microbial biomass subject to conventional farming and three different organic farming practices. The results showed that microbial biomass was P-limited in soils subject to conventional farming and to organic farming with alfalfa green manure. Organic farming with compost amendment showed the best results in terms of microbial biomass carbon, nitrogen and phosphorus (CNP).
Abstract Several insect species are mass produced for animal feeds, fish bait, or human consumpt... more Abstract Several insect species are mass produced for animal feeds, fish bait, or human consumption. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the more-popular insects considered for this use. To make T. molitor competitive with more-traditional protein sources, mass production must be optimized. Herein, we review the scientific literature on the range and optimal environmental, physical, and dietary conditions for the rearing T. molitor. Our review identified that: (a) the optimum temperature for T. molitor growth is 25–28°C; (b) T. molitor larval growth rate is greatest at ≥70% relative humidity (RH) with an optimum range between 60–75% RH, and; (c) optimal growth is achieved with diets containing 5–10% yeast, 80–85% carbohydrate, and the addition of B-complexvitamins.
To evaluate the importance and fate of organic matter inputs in forested streams, we determined t... more To evaluate the importance and fate of organic matter inputs in forested streams, we determined the litterfall inputs and the benthic coarse particulate organic matter (CPOM) in one headwater stream flowing through a mixed deciduous forest, during one year. Both vertical traps and the stream bottom were sampled monthly. The material collected was sorted into four main categories: leaves, fruits and flowers, twigs and debris. Litter production was 715 g m−2 y−1 and seasonal, with 73% of the annual total during October–December (autumn). Leaves comprised the largest litter component. Benthic organic matter was 1880 g m−2 y−1, and was also seasonal. Highest accumulation was attained in spring, and twigs and branches comprised the major component.
We evaluated the effect of seawater intrusion in coastal ecosystems on the freshwater invertebrat... more We evaluated the effect of seawater intrusion in coastal ecosystems on the freshwater invertebrate community and on leaf litter decomposition under realistic scenarios in six outdoor freshwater mesocosms containing fauna and flora, to which increasing volumes of seawater were added. The resulting salinity values were 0.28 (control, freshwater only), 2.0, 3.3, 5.5, 9.3, and 15.3 mS cm−1. The effect of salinity was assessed for 65 days after seawater intrusion, by computing the deviation of values in each treatment in relation to the control. Our results show that seawater intrusion into freshwaters will affect the invertebrate communities and organic matter decomposition, with salinities of up to 3.3–5.5 mS cm−1 having opposite effects to salinities of more than 9.3 mS cm−1. There was a net negative effect of the two highest salinities on mass loss and richness of the invertebrates associated with the decomposing leaves. Regarding the invertebrate communities of the mesocosms, there ...
Urbanization has deep impacts in streams affecting all aspects of the ecosystem. The distinctive ... more Urbanization has deep impacts in streams affecting all aspects of the ecosystem. The distinctive impacts of urbanization include the increase in impervious surfaces which in turn alters the hydrology and geomorphology of streams. Thus, urbanization affects not only water quality but also habitat characteristics. Biological indicators may reveal spatial-temporal effects of stressors and their cumulative effects on stream biota, and biotic indices based on intolerance to disturbance and taxonomic richness are effective and widely used to assess ecological health. But the multiple, co-occurring and interacting stressors of urban streams, namely habitat alterations, may be better revealed by macroinvertebrate traits - the species adaptations to environmental conditions. The aim of this study is to develop a broadly applicable and easy to use multi-trait biotic index based on macroinvertebrate adaptations to environmental conditions to evaluate urban stream health. The preliminary result...
This study evaluated if there are differences in leaf breakdown and invertebrate colonization amo... more This study evaluated if there are differences in leaf breakdown and invertebrate colonization among tree species differing in quality (toughness), and which factors could influence these differences. Com-mon alder leaves decomposed significantly faster then either sweet chestnut or Spanish oak (k values of – 0.0332, – 0.0108, and – 0.0112, respectively) during the first 2 months. Shredder abundance was high-est when leaf mass remaining was 50%, and the samples clustered in mixed groups of sampling dates and leaf species, suggesting that stage of decomposition was an important factor influencing shredder colonization. During the first two months of decomposition, the physicochemical characteristics of leaf litter and the interaction between leaf toughness and the occurrence of frequent spates seemed to be the main factors affecting leaf breakdown rates in the stream. 1.
This study assessed the effect of nutrient enrichment on rates of decomposition, ergosterol conce... more This study assessed the effect of nutrient enrichment on rates of decomposition, ergosterol concentrations (as a measure of fungal biomass), and rates of fungal sporulation of sweet chestnut (Castanea sativaMiller) leaves in a 3rd order stream (Central Portugal), with medium to high background values of nutrients. Coarse and fine mesh leaf bags were attached to nutrient diffusing substrata containing NaNO3, KH2PO4, both nutrients, or no additions. Leaf breakdown rates were similar in the four treatments and in the two mesh sizes (k=)0.0155 to)0.0219 day)1). Phosphorus content of P or N+P enriched leaves was higher than in the other treatments after 28 days, but there were no differences in N concentrations. Ergosterol concentrations associated with decomposing leaves were similar among treatments. The peak sporulation rates of aquatic hyphomycetes were stimulated by the addition of N+P and N but not by P alone. Results from the experiment provide evidence that leaf breakdown in the ...
Structure and diversity of the benthic macroinvertcbrate fauna were st~tdied in two deciduous for... more Structure and diversity of the benthic macroinvertcbrate fauna were st~tdied in two deciduous forest streams in Central Portugal. In the three sampling occasions. 120 tax-cl were collected from the two streams. Number of tci,xci per sampling occasion ranged from 53 to 60. Macroinvertebrate densities ranged from 1465 to 2365. Insects were the most abundant taxonomic group (280?h) in all samples. Detritivorous invertebrates were numerically dominant in both streams, representing 62 to 85 5 % of the total macroinvertebratc community.
ATP has been widely used to estimate total microbial biomass in a variety of systems (Karl 1980, ... more ATP has been widely used to estimate total microbial biomass in a variety of systems (Karl 1980, Maltby 1992, Gessner 1997, Abelho 2001). The ubiquitous distribution of ATP in living cells, the rapid loss from dead cells, the fairly constant concentrations in microorganisms (Holm-Hansen & Karl 1978), and the ease of
The role of carbon, nitrogen, and phosphorus in leaf decomposition mediated by aquatic fungi The ... more The role of carbon, nitrogen, and phosphorus in leaf decomposition mediated by aquatic fungi The aquatic microbial decomposition of leaf litter has been the subject of many field studies throughout the world. However, field experiments cannot always separate the effects of the multiple biotic and abiotic factors involved in the process. In this laboratory experiment, we controlled the abiotic factors and the fungal decomposer community during decomposition of alder, oak and eucalypt leaf litter in order to determine if variation in leaf carbon, nitrogen and phosphorus (CNP) ratios during decomposition was similar among the three species. Initial CNP values differed among the three species with alder being the richest (
Microorganisms play an important role as decomposers of plant litter in all environments. Various... more Microorganisms play an important role as decomposers of plant litter in all environments. Various approaches have been used to estimate their biomass in decomposing leaf litter, of which the quantification of ATP has been among the most popular, due to the ubiquitous distribution of ATP in living cells. This chapter describes a procedure to quantify ATP in decomposing leaf litter. The presented method involves cold acid extraction from leaves colonized by microorganisms, followed by quantification of ATP by luminometry using the firefly luciferin-luciferase reaction and internal ATP standards. The method has been successfully applied to quantify microbial biomass in a variety of environments. Where fungi dominate microbial biomass and the colonized plant tissue is dead, ATP can also be used to estimate fungal biomass as a rapid, easy, and relatively low-cost alternative to the quantification of ergosterol.
Respiration of heterotrophic organisms is an indicator of energy allocated to metabolism and henc... more Respiration of heterotrophic organisms is an indicator of energy allocated to metabolism and hence a general measure of biological activity. Therefore, respiration associated with plant litter can be used as an estimate of the functional significance of microbes in the decomposition process. This chapter describes procedures to measure respiration rates of both microbes and invertebrates in decomposing leaf litter. Respiration rates are determined by measuring oxygen consumption, either in closed or in open flow-through systems. The simplest closed system consists of a well-sealed water-filled flask without headspace, where oxygen concentrations are measured initially and again after a standard incubation period. More reliable estimates are obtained by continuously recording oxygen concentrations in respiration chambers equipped with oxygen electrodes. Alternatively, leaf samples or invertebrates are enclosed in flow-through chambers where respiration rate is determined as the diffe...
In this study we assessed the C : N : P ratios in soil and soil microbial biomass subject to conv... more In this study we assessed the C : N : P ratios in soil and soil microbial biomass subject to conventional farming and three different organic farming practices. The results showed that microbial biomass was P-limited in soils subject to conventional farming and to organic farming with alfalfa green manure. Organic farming with compost amendment showed the best results in terms of microbial biomass carbon, nitrogen and phosphorus (CNP).
Abstract Several insect species are mass produced for animal feeds, fish bait, or human consumpt... more Abstract Several insect species are mass produced for animal feeds, fish bait, or human consumption. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), is one of the more-popular insects considered for this use. To make T. molitor competitive with more-traditional protein sources, mass production must be optimized. Herein, we review the scientific literature on the range and optimal environmental, physical, and dietary conditions for the rearing T. molitor. Our review identified that: (a) the optimum temperature for T. molitor growth is 25–28°C; (b) T. molitor larval growth rate is greatest at ≥70% relative humidity (RH) with an optimum range between 60–75% RH, and; (c) optimal growth is achieved with diets containing 5–10% yeast, 80–85% carbohydrate, and the addition of B-complexvitamins.
To evaluate the importance and fate of organic matter inputs in forested streams, we determined t... more To evaluate the importance and fate of organic matter inputs in forested streams, we determined the litterfall inputs and the benthic coarse particulate organic matter (CPOM) in one headwater stream flowing through a mixed deciduous forest, during one year. Both vertical traps and the stream bottom were sampled monthly. The material collected was sorted into four main categories: leaves, fruits and flowers, twigs and debris. Litter production was 715 g m−2 y−1 and seasonal, with 73% of the annual total during October–December (autumn). Leaves comprised the largest litter component. Benthic organic matter was 1880 g m−2 y−1, and was also seasonal. Highest accumulation was attained in spring, and twigs and branches comprised the major component.
We evaluated the effect of seawater intrusion in coastal ecosystems on the freshwater invertebrat... more We evaluated the effect of seawater intrusion in coastal ecosystems on the freshwater invertebrate community and on leaf litter decomposition under realistic scenarios in six outdoor freshwater mesocosms containing fauna and flora, to which increasing volumes of seawater were added. The resulting salinity values were 0.28 (control, freshwater only), 2.0, 3.3, 5.5, 9.3, and 15.3 mS cm−1. The effect of salinity was assessed for 65 days after seawater intrusion, by computing the deviation of values in each treatment in relation to the control. Our results show that seawater intrusion into freshwaters will affect the invertebrate communities and organic matter decomposition, with salinities of up to 3.3–5.5 mS cm−1 having opposite effects to salinities of more than 9.3 mS cm−1. There was a net negative effect of the two highest salinities on mass loss and richness of the invertebrates associated with the decomposing leaves. Regarding the invertebrate communities of the mesocosms, there ...
Urbanization has deep impacts in streams affecting all aspects of the ecosystem. The distinctive ... more Urbanization has deep impacts in streams affecting all aspects of the ecosystem. The distinctive impacts of urbanization include the increase in impervious surfaces which in turn alters the hydrology and geomorphology of streams. Thus, urbanization affects not only water quality but also habitat characteristics. Biological indicators may reveal spatial-temporal effects of stressors and their cumulative effects on stream biota, and biotic indices based on intolerance to disturbance and taxonomic richness are effective and widely used to assess ecological health. But the multiple, co-occurring and interacting stressors of urban streams, namely habitat alterations, may be better revealed by macroinvertebrate traits - the species adaptations to environmental conditions. The aim of this study is to develop a broadly applicable and easy to use multi-trait biotic index based on macroinvertebrate adaptations to environmental conditions to evaluate urban stream health. The preliminary result...
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Papers by Manuela Abelho