scholarly journals Contribution of Fungi and Bacteria to Leaf Litter Decomposition in a Polluted River

2004 ◽  
Vol 70 (9) ◽  
pp. 5266-5273 ◽  
Author(s):  
Cláudia Pascoal ◽  
Fernanda Cássio
Keyword(s):  
Fungal Biomass ◽  
Stream Water ◽  
Inorganic Nitrogen ◽  
Aquatic Hyphomycetes ◽  
Microbial Production ◽  
Polluted Site ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Polluted Sites ◽  
Radiolabeled Compounds

ABSTRACT The contribution of fungi and bacteria to the decomposition of alder leaves was examined at two reference and two polluted sites in the Ave River (northwestern Portugal). Leaf mass loss, microbial production from incorporation rates of radiolabeled compounds into biomolecules, fungal biomass from ergosterol concentration, sporulation rates, and diversity of aquatic hyphomycetes associated with decomposing leaves were determined. The concentrations of organic nutrients and of inorganic nitrogen and phosphorus in the stream water was elevated and increased at downstream sites. Leaf decomposition rates were high (0.013 day−1 < k < 0.042 day−1), and the highest value was estimated at the most downstream polluted site, where maximum values of microbial production and fungal biomass and sporulation were found. The slowest decomposition occurred at the other polluted site, where, along with the nutrient enrichment, the lowest current velocity and dissolved-oxygen concentration in water were observed. At this site, fungal production, biomass, and sporulation were depressed, suggesting that stimulation of fungal activity by increased nutrient concentrations might be offset by other factors. Although bacterial production was higher at polluted sites, fungi accounted for more than 94% of the total microbial net production. Fungal yield coefficients varied from 10.2 to 13.6%, while those of bacteria were less than 1%. The contribution of fungi to overall leaf carbon loss (29.0 to 38.8%) greatly exceeded that of bacteria (4.2 to 13.9%).

scholarly journals Microbial Decomposer Communities Are Mainly Structured by Trophic Status in Circumneutral and Alkaline Streams

2009 ◽  
Vol 75 (19) ◽  
pp. 6211-6221 ◽  
Author(s):  
Sofia Duarte ◽  
Cláudia Pascoal ◽  
Frédéric Garabétian ◽  
Fernanda Cássio ◽  
Jean-Yves Charcosset
Keyword(s):  
Microbial Communities ◽  
Fungal Biomass ◽  
Trophic Status ◽  
Stream Water ◽  
Inorganic Nitrogen ◽  
Soluble Reactive Phosphorus ◽  
Bacterial Biomass ◽  
Nutrient Concentrations ◽  
Ammonium Concentration ◽  
Microbial Decomposer

ABSTRACT In streams, the release of nitrogen and phosphorus is reported to affect microbial communities and the ecological processes they govern. Moreover, the type of inorganic nitrogen (NO3, NO2, or NH4) may differently impact microbial communities. We aimed to identify the environmental factors that structure aquatic microbial communities and drive leaf litter decomposition along a gradient of eutrophication. We selected five circumneutral (Portuguese) and five alkaline (French) streams differing in nutrient concentrations to monitor mass loss of alder leaves, bacterial and fungal diversity by PCR-denaturing gradient gel electrophoresis, fungal biomass and reproduction, and bacterial biomass during 11 weeks of leaf immersion. The concentrations of inorganic nutrients in the stream water ranged from 5 to 300 μg liter−1 soluble reactive phosphorus, 0.30 to 5.50 mg liter−1 NO3-N, 2 to 103 μg liter−1 NO2-N, and <4 to 7,100 μg liter−1 NH4-N. Species richness was maximum in moderately anthropized (eutrophic) streams but decreased in the most anthropized (hypertrophic) streams. Different species assemblages were found in subsets of streams with different trophic statuses. In both geographic areas, the limiting nutrient, either nitrate or phosphate, stimulated the microbial activity in streams of intermediate trophic status. In the hypertrophic streams, fungal biomass and reproduction were significantly lower, and bacterial biomass dramatically decreased at the site with the highest ammonium concentration. The limiting nutrients that defined the trophic status were the main factor structuring fungal and bacterial communities, whatever the geographic area. A very high ammonium concentration in stream water most probably has negative impacts on microbial decomposer communities.

scholarly journals Flood water quality and marine sediment and nutrient loads from the Tully and Murray catchments in north Queensland, Australia

2009 ◽  
Vol 60 (11) ◽  
pp. 1123 ◽  
Author(s):  
Jim Wallace ◽  
Lachlan Stewart ◽  
Aaron Hawdon ◽  
Rex Keen ◽  
Fazlul Karim ◽  
...  
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Large Contribution ◽  
Nutrient Loads ◽  
Nitrogen And Phosphorus ◽  
Annual Average ◽  
Nitrogen Loads ◽  
Flood Flows

Current estimates of sediment and nutrient loads from the Tully–Murray floodplain to the Great Barrier Reef lagoon are updated by taking explicit account of flood events. New estimates of flood discharge that include over-bank flows are combined with direct measurements of sediment and nutrient concentrations in flood waters to calculate the loads of sediment and nutrient delivered to the ocean during 13 floods that occurred between 2006 and 2008. Although absolute concentrations of sediment and nutrient were quite low, the large volume of water discharged during floods means that they make a large contribution (30–50%) to the marine load. By not accounting for flood flows correctly, previous estimates of the annual average discharge are 15% too low and annual loads of nitrogen and phosphorus are 47% and 32% too low respectively. However, because sediments may be source-limited, accounting for flood flows simply dilutes their concentration and the resulting annual average load is similar to that previously estimated. Flood waters also carry more dissolved organic nitrogen than dissolved inorganic nitrogen and this is the opposite of their concentrations in river water. Consequently, dissolved organic nitrogen loads to the ocean may be around twice those previously estimated from riverine data.

Nutrients in Australian tropical rivers: changes with agricultural development and implications for receiving environments

2005 ◽  
Vol 56 (3) ◽  
pp. 279 ◽  
Author(s):  
Jon E. Brodie ◽  
Alan W. Mitchell
Keyword(s):  
Agricultural Development ◽  
Nutrient Dynamics ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Tropical Rivers ◽  
Nutrient Inputs ◽  
Material Transport ◽  
Nitrogen And Phosphorus ◽  
North East ◽  
The North

In tropical Australia, intensive studies of river suspended sediment (SS) and nutrient dynamics have been restricted to streams on the north-east coast between the Fitzroy and Normanby Rivers (Queensland), Magela Creek/East Alligator River (Northern Territory) and the Ord River (Western Australia). Historical conditions in these rivers were probably characterised by low–moderate SS concentrations and low concentrations of dissolved inorganic nitrogen and phosphorus in flow events. Introduction of agriculture has transformed SS and nutrient dynamics. Grazing has led to soil erosion and increased SS and particulate nutrient concentrations and fluxes in event flows. Fertilised cropping has increased nutrient inputs to catchments, where it forms a substantial proportion of the catchment area. Consequently, both particulate and dissolved inorganic nutrient concentrations and fluxes have increased. Australian tropical rivers have episodic flows, with most material transport occurring during large flow events. The restricted period of these highly energetic flows means little trapping of materials in waterways occurs. Loads are transported efficiently downstream and processes such as denitrification and in-channel sedimentation may be of limited importance. Owing to excessive nutrient inputs associated with agriculture, a number of northern freshwater, estuarine and coastal ecosystems are now eutrophic. Continued development, especially fertilised cropping, without adequate management of nutrient losses is likely to exacerbate these problems.

Influence of climate,geology and humans on spatial and temporal nutrient geochemistry in the subtropical Richmond River catchment, Australia

2001 ◽  
Vol 52 (2) ◽  
pp. 235 ◽  
Author(s):  
Lester J. McKee ◽  
Bradley D. Eyre ◽  
Shahadat Hossain ◽  
Peter R. Pepperell
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Agricultural Land ◽  
Anthropogenic Impacts ◽  
Inorganic Nitrogen ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
River Catchment

Water quality was monitored on a spatial and temporal basis in the subtropical Richmond River catchment over two years. Nutrient concentrations varied seasonally in a complex manner with highest concentrations (maximum =3110 µg N L – 1 and 572 µg P L –1 ) associated with floods. However, median (444 µg N L – 1 and 55 µg P L – 1 ) concentrations were relatively low compared with other parts of the world. The forms of nitrogen and phosphorus in streams varied seasonally, with greater proportions of inorganic nitrogen and phosphorus during the wet season. Minimum nutrient concentrations were found 2—3 months after flood discharge. With the onset of the dry season, concentration increases were attributed to point sources and low river discharge. There were statistically significant relationships between geology and water quality and nutrient concentrations increased downstream and were significantly related to population density and dairy farming. In spite of varying geology and naturally higher phosphorus in soils and rocks in parts of the catchment, anthropogenic impacts had the greatest effects on water quality in the Richmond River catchment. Rainfall quality also appeared to be related both spatially and seasonally to human activity. Although the responses of the subtropical Richmond River catchment to changes in land use are similar to those of temperate systems of North America and Europe, the seasonal patterns appear to be more complex and perhaps typical of subtropical catchments dominated by agricultural land use.

Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams

2002 ◽  
Vol 59 (5) ◽  
pp. 865-874 ◽  
Author(s):  
Walter K Dodds ◽  
Val H Smith ◽  
Kirk Lohman
Keyword(s):  
Stream Water ◽  
Water Quality Monitoring ◽  
The United States ◽  
Anthropogenic Effects ◽  
Nutrient Concentrations ◽  
Monitoring Networks ◽  
Stream Water Quality ◽  
Nitrogen And Phosphorus ◽  
Total N ◽  
Temperate Streams

Knowledge of factors limiting benthic algal (periphyton) biomass is central to understanding energy flow in stream ecosystems and stream eutrophication. We used several data sets to determine how water column nutrients and nonnutrient factors are linked to periphytic biomass and if the ecoregion concept is applicable to nutrient–periphyton relationships. Literature values for seasonal means of biomass of periphyton, nutrient concentrations, and other stream characteristics were collected for almost 300 sampling periods from temperate streams. Data for benthic chlorophyll and nutrient concentrations from a subset of 620 stations in the United States National Stream Water-Quality Monitoring Networks were also analyzed. The greatest portion of variance in models for the mean and maximum biomass of benthic stream algae (about 40%) was explained by concentrations of total N and P. Breakpoint regression and a two-dimensional Kolmogorov–Smirnov statistical technique established significant breakpoints of about 30 µg total P·L–1 and 40 µg total N·L–1, above which mean chlorophyll values were substantially higher. Ecoregion effects on nutrient–chlorophyll relationships were weak. Ecoregion effects were cross-correlated with anthropogenic effects such as percent urban and cropland area in the watershed and population density. Thus, caution is necessary to separate anthropogenic effects from natural variation at the ecoregion level.

scholarly journals Nitrogen and phosphorus recycling mediated by copepods in Western Tropical South Pacific

2018 ◽  
Author(s):  
Valentina Valdés ◽  
François Carlotti ◽  
Ruben Escribano ◽  
Katty Donoso ◽  
Marc Pagano ◽  
...  
Keyword(s):  
Community Composition ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
South Pacific ◽  
Nutrient Concentrations ◽  
Ammonium Concentration ◽  
Nitrogen And Phosphorus ◽  
In Situ Conditions

Abstract. Zooplankton play a key role in the regeneration of nitrogen and phosphorus in the ocean through grazing and metabolism. This study investigates the role of the organic and inorganic nitrogen and phosphorus compounds released by copepods on biogeochemical processes and on the microbial community composition during the OUTPACE cruise (18 February–3 April 2015) at three long duration stations (LD). Two LD stations were located in the Melanesian Archipelago region (MA; LD A and LD B) and one in the South Pacific Gyre (SG; LD C), which represent oligotrophic and ultraoligotrophic regions respectively. At each station, microcosm onboard experiments were performed with locally sampled organisms, comprising a mix of epipelagic copepods fed with their natural food and then incubated along with wild microbial assemblages. In presence of copepods, ammonium and dissolved organic nitrogen showed a significant increase, compared to a control in two situations: in ammonium concentration (increasing rate: 0.29 μmol L−1 h−1 after 4 h of incubation) in LD C and in dissolved organic nitrogen concentration (rate: 2.13 μmol L−1 h−1 after 0.5 h of incubation) in LD A. In addition, during the three experiments, an enhanced remineralization (ammonification and nitrification) was observed when adding copepods compared to the controls. A shift in the composition of active bacterial community was observed for the experiments in LD A and LD B mainly characterized by an increase in Alteromonadales and SAR11, respectively and linked with changes in nutrient concentrations. In the experiment performed in LD C, both groups increased but at different periods of incubation, Alteromonadales between 1 and 2 h after the beginning of the experiment, and SAR 11 at the end of incubation. Finally, our experimental results in near in situ conditions, show that copepods can be a source of organic and inorganic compounds for bacterial communities, which respond to excretion pulses at different scales, depending on the initial environmental conditions and on their community composition. These processes can contribute significantly to nutrient recycling in the epipelagic ecosystem of ultra and oligotrophic oceanic regions.

scholarly journals Nutrient concentrations and fluxes for podzolic and gley soils at Plynlimon, mid-Wales: implications for modelling inorganic nitrogen and phosphorus in upland UK environments

2002 ◽  
Vol 6 (3) ◽  
pp. 403-420
Author(s):  
C. Neal
Keyword(s):  
Inorganic Nitrogen ◽  
Soluble Reactive Phosphorus ◽  
Sitka Spruce ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Podzolic Soils ◽  
Forestry Management ◽  
Order Of Magnitude ◽  
Reactive Phosphorus ◽  
Stream Nitrate

Abstract. The effect of felling on stream nitrate, ammonium and soluble reactive phosphate (SRP) concentrations is examined for acidic and acid sensitive Sitka Spruce afforested catchments with podzolic and gley soils in mid-Wales. For the streams draining the felled podzolic areas, the concentrations of nitrate can be up to an order of magnitude higher than pre-fell values and post-fell concentrations can even be lower than the pre-fell values. Felling for the podzolic soils barely leads to any changes in ammonium or SRP concentration. For the gley soils, felling results in an order of magnitude increase in nitrate, ammonium and SRP for a small drainage ditch, but the pulse is much reduced before it reaches the main Nant Tanllwyth channel. Rather, within-catchment and within-stream processes not only imbibe nitrate, ammonium and SRP fluxes generated, but in the case of nitrate, concentrations with- and post-felling are lower than pre-felling concentrations. The flux changes involved are described in terms of (a) input-output relationships and (b) "felling disruption" and "felling recovery responses". The findings are linked to issues of hydrobiological controls and forestry management. Keywords: Plynlimon, Hafren, Hore, streams, nitrate, ammonium, SRP, phosphorus, soluble reactive phosphorus, phosphate, orthophosphate, Sitka spruce, forestry, felling, podzol, gley

scholarly journals Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1531
Author(s):  
Konstantinos Stefanidis ◽  
Aikaterini Christopoulou ◽  
Serafeim Poulos ◽  
Emmanouil Dassenakis ◽  
Elias Dimitriou
Keyword(s):  
Water Framework Directive ◽  
Inorganic Nitrogen ◽  
Inorganic Phosphorus ◽  
Point Sources ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Land Uses ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Loads ◽  
Phosphorus Loads

Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).

scholarly journals Nitrogen and phosphorus recycling mediated by copepods and response of bacterioplankton community from three contrasting areas in the western tropical South Pacific (20° S)

2018 ◽  
Vol 15 (20) ◽  
pp. 6019-6032 ◽  
Author(s):  
Valentina Valdés ◽  
François Carlotti ◽  
Ruben Escribano ◽  
Katty Donoso ◽  
Marc Pagano ◽  
...  
Keyword(s):  
Community Composition ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
South Pacific ◽  
Nutrient Concentrations ◽  
Ammonium Concentration ◽  
Nitrogen And Phosphorus ◽  
In Situ Conditions

Abstract. Zooplankton play a key role in the regeneration of nitrogen and phosphorus in the ocean through grazing and metabolism. This study investigates the role of the organic and inorganic nitrogen and phosphorus compounds released by copepods on biogeochemical processes and on the microbial community composition during the OUTPACE cruise (18 February–3 April 2015) at three long-duration stations (LD). Two LD stations were located in the Melanesian Archipelago region (MA; LD A and LD B) and one in the South Pacific Gyre (SG; LD C), which represent oligotrophic and ultra-oligotrophic regions respectively. At each station, on-board microcosm experiments were performed with locally sampled organisms, comprising a mix of epipelagic copepods fed with their natural food and then incubated along with wild microbial assemblages. In the presence of copepods, ammonium and dissolved organic nitrogen showed a significant increase compared to a control in two situations: in ammonium concentration (rate: 0.29 µmol L−1 h−1 after 4 h of incubation) in LD C and in dissolved organic nitrogen concentration (rate: 2.13 µmol L−1 h−1 after 0.5 h of incubation) in LD A. In addition, during the three experiments, an enhanced remineralization (ammonification and nitrification) was observed when adding copepods compared to the controls. A shift in the composition of the active bacterial community was observed for the experiments in LD A and LD B, which were mainly characterized by an increase in Alteromonadales and SAR11, respectively, and linked with changes in nutrient concentrations. In the experiment performed in LD C, both groups increased but at different periods of incubation. Alteromonadales increased between 1 and 2 h after the beginning of the experiment, and SAR 11 at the end of incubation. Our results in near in situ conditions show that copepods can be a source of organic and inorganic compounds for bacterial communities, which respond to excretion pulses at different timescales, depending on the initial environmental conditions and on their community composition. These processes can significantly contribute to nutrient recycling and regenerated production in the photic zone of ultra-oligotrophic and oligotrophic oceanic regions.

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