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Francesc Sabater - One of the best experts on this subject based on the ideXlab platform.
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effect of three emergent macrophyte species on Nutrient Retention in aquatic environments under excess Nutrient loading
Environmental Science & Technology, 2020Co-Authors: Myrto Nikolakopoulou, Eugenia Marti, Miquel Ribot, Alba Argerich, Susana Bernal, Esperanca Gacia, Albert Sorolla, Francesc SabaterAbstract:Emergent macrophyte species selection is critical for the effectiveness of nature-based engineered solutions aiming to address excess Nutrient concentrations in freshwater ecosystems. Yet, the mechanisms with which macrophytes enhance Nutrient Retention need to be further understood. Here, we compared Nutrient Retention among 12 artificial flumes fed with effluents from a wastewater treatment plant and subjected to four treatments: absence of macrophytes (control) and presence of three different macrophyte species (Iris pseudacorus L., Phragmites australis L., and Schoenoplectus lacustris L.). We estimated the net and gross Nutrient uptake based on the longitudinal profiles of ambient concentrations and on pulse injections of ammonium (NH4+) and soluble reactive phosphorus. Further, we investigated the influence of subsurface hydrological Retention, attributed to the architectural differences in the roots of these macrophytes, on Nutrient Retention. Results showed a species-specific effect of macrophytes on Nutrient Retention and confirmed root-associated subsurface hydrological Retention as a driving factor. Schoenoplectus showed both high net and gross NH4+ uptake, thereby being the most effective species to address N loading, compared to Iris and Phragmites. This work contributes to improve our mechanistic understanding of the role of emergent macrophytes on Nutrient Retention in aquatic environments.
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influence of land use on stream ecosystem function in a mediterranean catchment
Freshwater Biology, 2008Co-Authors: D Von Schiller, Eugenia Marti, Joan Lluis Riera, Miquel Ribot, Jane C Marks, Francesc SabaterAbstract:SUMMARY 1. Due to the hierarchical organization of stream networks, land use changes occurring at larger spatial scales (i.e. the catchment) can affect physical, chemical and biological characteristics at lower spatial scales, ultimately altering stream structure and function. Anthropogenic effects on streams have primarily been documented using structural metrics such as water chemistry, channel alteration and algal biomass. Functional parameters, including metrics of Nutrient Retention and metabolism, are now being widely used as indicators of stream condition. 2. Within this hierarchical context, we used a multivariate approach to examine how structural and functional (i.e. Nutrient Retention and metabolism) attributes of streams are related to catchment variables, including land use. The study was done in 13 streams located within a single Mediterranean catchment, but draining sub-catchments with contrasting land use. 3. At the catchment scale, results showed two contrasting land use gradients: (i) from forested- to urban-dominated catchments and (ii) from low to moderate agriculturaldominated catchments. Variation in structural and functional parameters was strongly related to these land use gradients. Specifically, NH4 + demand (measured as the uptake velocity, Vf) decreased along the gradient from forested- to urban-dominated catchments primarily in response to increases in stream Nutrient concentrations [NH4 + , dissolved organic nitrogen (DON) and carbon (DOC)]. Both primary production and respiration increased along the gradient of agricultural development in response to increases in algal biomass (chlorophyll a). Soluble reactive phosphorus demand was not related to any of the land use gradients. 4. Our results illustrate the connections among factors operating at different spatial scales (i.e. from catchments to streams) and their distinct influence on stream ecosystem function. Managers should take into consideration these connections when designing stream management and restoration plans. Because ecologically successful stream management and restoration is expected to restore function as well as structure to streams, the use of appropriate measures of functional processes is required. Nutrient Retention and metabolism parameters are good candidates to fill this gap.
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Inter-annual, Annual, and Seasonal Variation of P and N Retention in a Perennial and an Intermittent Stream
Ecosystems, 2008Co-Authors: Daniel Von Schiller, Eugenia Marti, Joan Lluis Riera, Miquel Ribot, Alba Argerich, Paula Fonollà, Francesc SabaterAbstract:Headwater streams represent the key sites of Nutrient Retention, but little is known about temporal variation in this important process. We used monthly measurements over 2 years to examine variation in Retention of soluble reactive phosphorus (SRP) and ammonium (NH _4 ^+ ) in two Mediterranean headwater streams with contrasting hydrological regimes (that is, perennial versus intermittent). Differences in Retention between streams were more evident for NH _4 ^+ , likely due to strong differences in the potential for nitrogen limitation. In both streams, Nutrient-Retention efficiency was negatively influenced by abrupt discharge changes, whereas gradual seasonal changes in SRP demand were partially controlled by riparian vegetation dynamics through changes in organic matter and light availability. Nutrient concentrations were below saturation in the two streams; however, SRP demand increased relative to NH _4 ^+ demand in the intermittent stream as the potential for phosphorus limitation increased (that is, higher dissolved inorganic nitrogen:SRP ratio). Unexpectedly, variability in Nutrient Retention was not greater in the intermittent stream, suggesting high resilience of biological communities responsible for Nutrient uptake. Within-stream variability of all Retention metrics, however, increased with increasing time scale. A review of studies addressing temporal variation of Nutrient Retention at different time scales supports this finding, indicating increasing variability of Nutrient Retention with concomitant increases in the variability of environmental factors from the diurnal to the inter-annual scale. Overall, this study emphasizes the significance of local climate conditions in regulating Nutrient Retention and points to potential effects of changes in land use and climate regimes on the functioning of stream ecosystems.
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combined effects of leaf litter inputs and a flood on Nutrient Retention in a mediterranean mountain stream during fall
Limnology and Oceanography, 2008Co-Authors: Alba Argerich, Eugenia Marti, Miquel Ribot, Francesc Sabater, Daniel Von Schiller, Joan Lluis RieraAbstract:This study examined the effect of increasing in-channel leaf standing stocks on hydrologic transient storage and Nutrient Retention in a Mediterranean mountain stream. A flood at the end of the leaf fall period provided the opportunity to examine the effect of abrupt removal of much of the leaf material. Twenty-one chloride additions were performed from October to December 2004. In 13 of these, we also added ammonium and phosphate to estimate Nutrient uptake lengths and uptake velocities to assess Nutrient Retention. The one-dimensional transport with inflow and storage (OTIS) model was used to estimate transient water storage parameters. Although discharge remained constant during leaf fall, water residence time increased because of in-channel litter accumulation, as did Nutrient uptake velocity. Flooding reduced leaf benthic standing stocks by 65% and dramatically altered hydraulic and Nutrient Retention properties of the channel. After recession, the stream rapidly recovered in terms of Nutrient Retention, especially for phosphate. Abrupt changes in discharge under flood conditions largely determined the variability in stream Nutrient Retention. However, leaf litter inputs played an important role in Nutrient dynamics during constant flow. Because both the flood regime and the timing of leaf fall are being regionally altered by climate change, our results have implications for stream Nutrient dynamics under climate change scenarios.
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Nutrient Retention efficiency in streams receiving inputs from wastewater treatment plants
Journal of Environmental Quality, 2004Co-Authors: Eugenia Marti, Jordi Aumatell, Lluis Gode, Manel Poch, Francesc SabaterAbstract:We tested the effect of Nutrient inputs from wastewater treatment plants (WWTPs) on stream Nutrient Retention efficiency by examining the longitudinal patterns of ammonium, nitrate, and phosphate concentrations downstream of WWTP effluents in 15 streams throughout Catalonia (Spain). We hypothesized that large Nutrient loadings would saturate stream communities, lowering Nutrient Retention efficiency (i.e., Nutrient Retention relative to Nutrient flux) relative to less polluted streams. Longitudinal variation in ambient Nutrient concentration reflected the net result of physical, chemical, or biological uptake and release processes. Therefore, gradual increases in Nutrient concentration indicate that the stream acts as a net source of Nutrients to downstream environments, whereas gradual declines indicate that the stream acts as a net sink. In those streams where gradual declines in Nutrient concentration were observed, we calculated the Nutrient uptake length as an indicator of the stream Nutrient Retention efficiency. No significant decline was found in dilution-corrected concentrations of dissolved inorganic nitrogen (DIN) and phosphate in 40 and 45% of streams, respectively. In the remaining streams, uptake length (estimated based on the decline of Nutrient concentrations at ambient levels) ranged from 0.14 to 29 km (DIN), and from 0.14 to 14 km (phosphate). Overall, these values are longer (lower Retention efficiency) than those from nonpolluted streams of similar size, supporting our hypothesis, and suggest that high Nutrient loads affect fluvial ecosystem function. This study demonstrates that the efficiency of stream ecosystems to remove Nutrients has limitations because it can be significantly altered by the quantity and quality of the receiving water.
G G Mateos - One of the best experts on this subject based on the ideXlab platform.
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effects of wheat inclusion and xylanase supplementation of the diet on productive performance Nutrient Retention and endogenous intestinal enzyme activity of laying hens
Poultry Science, 2012Co-Authors: S Mirzaie, M Shivazad, Saeed Aminzadeh, M Zaghari, G G MateosAbstract:Abstract An experiment was conducted to study the effects of inclusion of a wheat cultivar (high in nonstarch polysaccharides) and xylanase supplementation of the diet on productive performance, pH of the gastrointestinal tract, Nutrient Retention, and intestinal enzyme activity of Hy-Line W-36 laying hens from 25 to 47 wk of age. The experiment was completely randomized with 8 treatments arranged factorially with 4 levels of wheat (0, 23, 46, and 69%) that corresponded to a dietary arabinoxylan content of 3.0, 3.3, 3.6, and 3.9%, with or without xylanase supplementation. Each treatment was replicated 5 times. For the entire experimental period, egg weight (P
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effects of wheat inclusion and xylanase supplementation of the diet on productive performance Nutrient Retention and endogenous intestinal enzyme activity of laying hens
Poultry Science, 2012Co-Authors: S Mirzaie, M Shivazad, Saeed Aminzadeh, M Zaghari, G G MateosAbstract:An experiment was conducted to study the effects of inclusion of a wheat cultivar (high in nonstarch polysaccharides) and xylanase supplementation of the diet on productive performance, pH of the gastrointestinal tract, Nutrient Retention, and intestinal enzyme activity of Hy-Line W-36 laying hens from 25 to 47 wk of age. The experiment was completely randomized with 8 treatments arranged factorially with 4 levels of wheat (0, 23, 46, and 69%) that corresponded to a dietary arabinoxylan content of 3.0, 3.3, 3.6, and 3.9%, with or without xylanase supplementation. Each treatment was replicated 5 times. For the entire experimental period, egg weight (P < 0.05) and egg mass (P < 0.01) were reduced and the feed conversion ratio was hindered (P < 0.05) with increased levels of wheat in the diet, but ADFI and egg production were not affected. Xylanase supplementation improved egg production (P < 0.05), egg mass (P < 0.01), and the feed conversion ratio (P < 0.01). Diet did not affect egg quality at any age, except for shell thickness at 47 wk that was improved with xylanase supplementation (P < 0.05). Digesta pH of the different organs of the gastrointestinal tract was not affected by wheat inclusion or xylanase supplementation. Ileal viscosity increased (P < 0.001) with wheat inclusion and decreased (P < 0.001) with xylanase supplementation at all ages. Fat digestibility (P < 0.001) decreased with increased levels of wheat but AME(n) content of the diets (P < 0.05) and nitrogen Retention were not affected. Wheat inclusion increased (P < 0.001) amylase (33 wk), lipase (33 wk), and aminopeptidase (47 wk) activity in the duodenum as well as lipase activity in the jejunum at 47 wk of age. However, xylanase supplementation did not affect the activity of any of the enzymes studied. It is concluded that most of the negative effects of wheat inclusion in the diet were reduced or even disappeared with xylanase supplementation. Wheat with a high nonstarch polysaccharide content (Pishtaz cultivar) can be used at levels of up to 69% in laying-hen diets without negatively affecting bird performance, provided that feeds are supplemented with xylanase.
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effects of increasing levels of pea hulls in the diet on productive performance development of the gastrointestinal tract and Nutrient Retention of broilers from one to eighteen days of age
Animal Feed Science and Technology, 2011Co-Authors: E Jimenezmoreno, R Lazaro, Susana Chamorro, M Frikha, H M Safaa, G G MateosAbstract:Abstract The effects of inclusion of pea hulls (PH) in the diet on growth performance, development of the gastrointestinal tract and Nutrient Retention were studied in broilers from 1 to 18 d of age. There were a control diet based on low fibre ingredients (69.3 total dietary fibre (16.1 g crude fibre/kg)) and three additional diets that resulted from the dilution of the basal diet with 25, 50 and 75 g PH/kg (81.2, 93.2, and 105.1 g total dietary fibre/kg diet, respectively). Each treatment was replicated six times and the experimental unit was a cage with 12 chicks. Growth performance, development of the gastrointestinal tract and the coefficients of total tract apparent Retention (CTTAR) of Nutrients were recorded at 6, 12 and 18 d of age. In addition, jejunal morphology was measured at 12 and 18 d and the coefficients of apparent ileal digestibility (CAID) of Nutrients at 18 d of age. Pea hulls inclusion affected all the parameters studied. The inclusion of 25 and 50 g PH/kg diet improved growth performance as compared to the control diet. The relative weight (g/kg body weight) of proventriculus (P≤0.01), gizzard (P≤0.001) and ceca (P≤0.05) increased linearly as the level of PH in the diet increased. The inclusion of PH affected quadratically (P≤0.01) villus height:crypt depth ratio with the highest value shown at 25 g PH/kg. In general, the CTTAR and CAID of Nutrients increased linearly and quadratically (P≤0.05) with increasing levels of PH, showing maximum values with PH level between 25 and 50 g/kg diet. We conclude that the size of the digestive organs increases with increasing levels of PH in the diet. In general, the best performance and Nutrient digestibility values were observed with levels of PH within the range of 25 and 50 g/kg. Therefore, young broilers have a requirement for a minimum amount of dietary fibre. When pea hulls are used as a source of fibre, the level of total dietary fibre required for optimal performance is within the range of 81.2–93.2 g/kg diet (25.6–35.0 g crude fibre/kg diet). An excess of total dietary fibre (above 93.2 g/kg diet) might reduce Nutrient digestibility and growth performance to values similar to those observed with the control diet.
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comparative study of two analytical procedures for the determination of acid insoluble ash for evaluation of Nutrient Retention in broilers
Spanish Journal of Agricultural Research, 2011Co-Authors: A De Cocasinova, G G Mateos, J M Gonzalezalvarado, Carmen Centeno, R Lazaro, E JimenezmorenoAbstract:Inert markers are routinely used in research to estimate Nutrient Retention and apparent metabolisable energy nitrogen-corrected (AMEn) content of poultry diets. Acid insoluble ash (AIA) is used as a marker to substitute metal compounds because of environmental concerns. In the current research, two methodologies recommended for determining AIA content in feeds and excretas for the evaluation of total tract apparent Retention (TTAR) of Nutrients, were compared in 12 broiler diets. The experimental design was completely randomised with 2 AIA analytical techniques and 12 dietary treatments that resulted from a combination of two cereals (corn and rice), two heat processing of the cereal (raw and cooked) and three fiber sources (control with no added fibre, 3% oat hulls and 3% soybean hulls). All diets included 1% celite (diatomaceous earth) as additional source of AIA. The techniques used for AIA determination were coded as VO and GA, respectively. The TTAR of dry matter and organic matter and the AMEn of the feeds differed (p ≤ 0.001) among diets and were lower when using GA than when using VO (p ≤ 0.05). However, no interaction between diet and methodology was observed. Moreover, the TTAR of Nutrients as determined by both techniques, were highly correlated (r > 0.98). We concluded that the GA methodology results in lower Retention values than the VO methodology but that both methodologies can be used indistinctly to estimate TTAR of Nutrients in broiler feeds. Additional key words: analytical methodologies; inert markers; metabolisable energy; Nutrient digestibility; poultry.
Eugenia Marti - One of the best experts on this subject based on the ideXlab platform.
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effect of three emergent macrophyte species on Nutrient Retention in aquatic environments under excess Nutrient loading
Environmental Science & Technology, 2020Co-Authors: Myrto Nikolakopoulou, Eugenia Marti, Miquel Ribot, Alba Argerich, Susana Bernal, Esperanca Gacia, Albert Sorolla, Francesc SabaterAbstract:Emergent macrophyte species selection is critical for the effectiveness of nature-based engineered solutions aiming to address excess Nutrient concentrations in freshwater ecosystems. Yet, the mechanisms with which macrophytes enhance Nutrient Retention need to be further understood. Here, we compared Nutrient Retention among 12 artificial flumes fed with effluents from a wastewater treatment plant and subjected to four treatments: absence of macrophytes (control) and presence of three different macrophyte species (Iris pseudacorus L., Phragmites australis L., and Schoenoplectus lacustris L.). We estimated the net and gross Nutrient uptake based on the longitudinal profiles of ambient concentrations and on pulse injections of ammonium (NH4+) and soluble reactive phosphorus. Further, we investigated the influence of subsurface hydrological Retention, attributed to the architectural differences in the roots of these macrophytes, on Nutrient Retention. Results showed a species-specific effect of macrophytes on Nutrient Retention and confirmed root-associated subsurface hydrological Retention as a driving factor. Schoenoplectus showed both high net and gross NH4+ uptake, thereby being the most effective species to address N loading, compared to Iris and Phragmites. This work contributes to improve our mechanistic understanding of the role of emergent macrophytes on Nutrient Retention in aquatic environments.
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influence of land use on stream ecosystem function in a mediterranean catchment
Freshwater Biology, 2008Co-Authors: D Von Schiller, Eugenia Marti, Joan Lluis Riera, Miquel Ribot, Jane C Marks, Francesc SabaterAbstract:SUMMARY 1. Due to the hierarchical organization of stream networks, land use changes occurring at larger spatial scales (i.e. the catchment) can affect physical, chemical and biological characteristics at lower spatial scales, ultimately altering stream structure and function. Anthropogenic effects on streams have primarily been documented using structural metrics such as water chemistry, channel alteration and algal biomass. Functional parameters, including metrics of Nutrient Retention and metabolism, are now being widely used as indicators of stream condition. 2. Within this hierarchical context, we used a multivariate approach to examine how structural and functional (i.e. Nutrient Retention and metabolism) attributes of streams are related to catchment variables, including land use. The study was done in 13 streams located within a single Mediterranean catchment, but draining sub-catchments with contrasting land use. 3. At the catchment scale, results showed two contrasting land use gradients: (i) from forested- to urban-dominated catchments and (ii) from low to moderate agriculturaldominated catchments. Variation in structural and functional parameters was strongly related to these land use gradients. Specifically, NH4 + demand (measured as the uptake velocity, Vf) decreased along the gradient from forested- to urban-dominated catchments primarily in response to increases in stream Nutrient concentrations [NH4 + , dissolved organic nitrogen (DON) and carbon (DOC)]. Both primary production and respiration increased along the gradient of agricultural development in response to increases in algal biomass (chlorophyll a). Soluble reactive phosphorus demand was not related to any of the land use gradients. 4. Our results illustrate the connections among factors operating at different spatial scales (i.e. from catchments to streams) and their distinct influence on stream ecosystem function. Managers should take into consideration these connections when designing stream management and restoration plans. Because ecologically successful stream management and restoration is expected to restore function as well as structure to streams, the use of appropriate measures of functional processes is required. Nutrient Retention and metabolism parameters are good candidates to fill this gap.
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Inter-annual, Annual, and Seasonal Variation of P and N Retention in a Perennial and an Intermittent Stream
Ecosystems, 2008Co-Authors: Daniel Von Schiller, Eugenia Marti, Joan Lluis Riera, Miquel Ribot, Alba Argerich, Paula Fonollà, Francesc SabaterAbstract:Headwater streams represent the key sites of Nutrient Retention, but little is known about temporal variation in this important process. We used monthly measurements over 2 years to examine variation in Retention of soluble reactive phosphorus (SRP) and ammonium (NH _4 ^+ ) in two Mediterranean headwater streams with contrasting hydrological regimes (that is, perennial versus intermittent). Differences in Retention between streams were more evident for NH _4 ^+ , likely due to strong differences in the potential for nitrogen limitation. In both streams, Nutrient-Retention efficiency was negatively influenced by abrupt discharge changes, whereas gradual seasonal changes in SRP demand were partially controlled by riparian vegetation dynamics through changes in organic matter and light availability. Nutrient concentrations were below saturation in the two streams; however, SRP demand increased relative to NH _4 ^+ demand in the intermittent stream as the potential for phosphorus limitation increased (that is, higher dissolved inorganic nitrogen:SRP ratio). Unexpectedly, variability in Nutrient Retention was not greater in the intermittent stream, suggesting high resilience of biological communities responsible for Nutrient uptake. Within-stream variability of all Retention metrics, however, increased with increasing time scale. A review of studies addressing temporal variation of Nutrient Retention at different time scales supports this finding, indicating increasing variability of Nutrient Retention with concomitant increases in the variability of environmental factors from the diurnal to the inter-annual scale. Overall, this study emphasizes the significance of local climate conditions in regulating Nutrient Retention and points to potential effects of changes in land use and climate regimes on the functioning of stream ecosystems.
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combined effects of leaf litter inputs and a flood on Nutrient Retention in a mediterranean mountain stream during fall
Limnology and Oceanography, 2008Co-Authors: Alba Argerich, Eugenia Marti, Miquel Ribot, Francesc Sabater, Daniel Von Schiller, Joan Lluis RieraAbstract:This study examined the effect of increasing in-channel leaf standing stocks on hydrologic transient storage and Nutrient Retention in a Mediterranean mountain stream. A flood at the end of the leaf fall period provided the opportunity to examine the effect of abrupt removal of much of the leaf material. Twenty-one chloride additions were performed from October to December 2004. In 13 of these, we also added ammonium and phosphate to estimate Nutrient uptake lengths and uptake velocities to assess Nutrient Retention. The one-dimensional transport with inflow and storage (OTIS) model was used to estimate transient water storage parameters. Although discharge remained constant during leaf fall, water residence time increased because of in-channel litter accumulation, as did Nutrient uptake velocity. Flooding reduced leaf benthic standing stocks by 65% and dramatically altered hydraulic and Nutrient Retention properties of the channel. After recession, the stream rapidly recovered in terms of Nutrient Retention, especially for phosphate. Abrupt changes in discharge under flood conditions largely determined the variability in stream Nutrient Retention. However, leaf litter inputs played an important role in Nutrient dynamics during constant flow. Because both the flood regime and the timing of leaf fall are being regionally altered by climate change, our results have implications for stream Nutrient dynamics under climate change scenarios.
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Nutrient Retention efficiency in streams receiving inputs from wastewater treatment plants
Journal of Environmental Quality, 2004Co-Authors: Eugenia Marti, Jordi Aumatell, Lluis Gode, Manel Poch, Francesc SabaterAbstract:We tested the effect of Nutrient inputs from wastewater treatment plants (WWTPs) on stream Nutrient Retention efficiency by examining the longitudinal patterns of ammonium, nitrate, and phosphate concentrations downstream of WWTP effluents in 15 streams throughout Catalonia (Spain). We hypothesized that large Nutrient loadings would saturate stream communities, lowering Nutrient Retention efficiency (i.e., Nutrient Retention relative to Nutrient flux) relative to less polluted streams. Longitudinal variation in ambient Nutrient concentration reflected the net result of physical, chemical, or biological uptake and release processes. Therefore, gradual increases in Nutrient concentration indicate that the stream acts as a net source of Nutrients to downstream environments, whereas gradual declines indicate that the stream acts as a net sink. In those streams where gradual declines in Nutrient concentration were observed, we calculated the Nutrient uptake length as an indicator of the stream Nutrient Retention efficiency. No significant decline was found in dilution-corrected concentrations of dissolved inorganic nitrogen (DIN) and phosphate in 40 and 45% of streams, respectively. In the remaining streams, uptake length (estimated based on the decline of Nutrient concentrations at ambient levels) ranged from 0.14 to 29 km (DIN), and from 0.14 to 14 km (phosphate). Overall, these values are longer (lower Retention efficiency) than those from nonpolluted streams of similar size, supporting our hypothesis, and suggest that high Nutrient loads affect fluvial ecosystem function. This study demonstrates that the efficiency of stream ecosystems to remove Nutrients has limitations because it can be significantly altered by the quantity and quality of the receiving water.
David A J Stone - One of the best experts on this subject based on the ideXlab platform.
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the use of a soy product in juvenile yellowtail kingfish seriola lalandi feeds at different water temperatures 1 solvent extracted soybean meal
Aquaculture, 2013Co-Authors: Jenna N Bowyer, Jian G Qin, Richard P Smullen, Louise R Adams, Michael J S Thomson, David A J StoneAbstract:Juvenile yellowtail kingfish (Seriola lalandi) were fed four iso-nitrogenous and iso-calorific (digestible basis) experimental diets containing 0, 10, 20 or 30% solvent extracted soybean meal (SESBM) for 34 days at optimal (22 °C) and suboptimal (18 °C) water temperatures to determine the effects of diet and water temperature on growth, feed efficiency, Nutrient Retention, apparent Nutrient digestibility and digestive functions. The substitution of fish meal up to 20% SESBM did not significantly affect the growth of fish. No differences were detected in any of the other parameters measured between 0 and 10% inclusion. However, second-order polynomial regression demonstrated that increasing SESBM had a negative effect on growth performance, feed efficiency, Nutrient Retention and the apparent Nutrient and energy digestibility of diets for yellowtail kingfish. Whole body moisture, crude lipid, ash and gross energy were affected by SESBM in the diet, except protein. The apparent Nutrient and energy digestibilities all decreased linearly with increasing SESBM. Digestive enzyme activities in the pyloric caeca were not affected by diet, whereas activities in the foregut and hindgut varied with SESBM inclusion. Fish held at 18 °C had significantly reduced growth, feed efficiency and Nutrient Retention values. The whole body moisture increased at 18 °C, while the apparent Nutrient and energy digestibilities and whole body protein and gross energy content were lower at 18 °C and there was no effect of temperature on whole body total fat or ash content. The impact of temperature on digestive enzyme activities depended on the section of the digestive tract. This study demonstrates that 10% inclusion of SESBM (21.7% fish meal substitution) can be used as a substitute for fish meal in diets for yellowtail kingfish.
Carol A Johnston - One of the best experts on this subject based on the ideXlab platform.
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sediment and Nutrient Retention by freshwater wetlands effects on surface water quality
Critical Reviews in Environmental Science and Technology, 1991Co-Authors: Carol A JohnstonAbstract:Abstract Freshwater wetlands alter surface water quality in ways which benefit downstream use. This review summarizes the mechanisms of freshwater wetland interaction with sediment and Nutrients that affect surface water quality. The mechanisms vary in magnitude and reversibility, and differ among wetland types. They include sedimentation, plant uptake, litter decomposition, Retention in the soil, and microbial processes. Sedimentation is a relatively permanent Retention mechanism whereby particulates and associated contaminants are physically deposited on the wetland soil surface. Plant uptake and litter decomposition provide short‐to long‐term Retention of Nutrients, depending on rates of leaching, translocation to and from storage structures, and the longevity of plant tissues. Plant litter can also provide a substrate for microbial processing of Nutrients. Wetland soils sorb Nutrients, and provide the environment for aerobic and anaerobic microorganisms that process Nutrients. Wetland storage compartm...
