Estuarine algal responses to increasing nitrate concentrations during closed mouth conditions of oligotrophic systems: a laboratory microcosm experiment

2018 ◽  
Vol 61 (6) ◽  
pp. 559-572 ◽  
Author(s):  
Daniel Alan Lemley ◽  
Monique Nunes ◽  
Janine Barbara Adams
Keyword(s):  
Community Dynamics ◽  
Temporal Dynamics ◽  
Inorganic Nitrogen ◽  
Algal Growth ◽  
Experimental Period ◽  
High Water ◽  
Algal Community ◽  
Microcosm Experiment ◽  
Nitrate Addition ◽  
Enriched Environments

AbstractThe increasing incidence of eutrophication has potentially detrimental socio-economic and ecological consequences. This study aimed to elucidate the temporal dynamics of algal communities in response to increasing initial concentrations of inorganic nitrogen (particularly nitrate) – central components of eutrophication. A contained microcosm experiment was designed to mimic the conditions of shallow oligotrophic estuaries with high water residence times. Phytoplankton, microphytobenthos and filamentous algal community dynamics were observed over a 28-day experimental period under different nitrate regimes. Key observations included (1) accelerated filamentous algal growth, (2) rapid loss of phytoplankton biomass and abundance, and (3) reduced benthic diatom species diversity and richness in the “1.0 μmNitrate Addition” treatment. Additionally, model results highlighted the positive relationship between filamentous algal growth and increased water temperature. From a global change perspective, the decline in microalgal abundance and diversity at the onset of filamentous algal growth in warm, N-enriched environments suggests a potential uncoupling of trophic pathways. However, the “Control” and “0.5 μmNitrate Addition” treatments were similar in their algal responses, highlighting the ability of ecosystems to absorb small disturbances. Thus, it is critical that estuarine resilience is preserved to ensure continued provision of invaluable ecosystem services.

Dinitrogen fixation and nodulation by Frankia in Alnus incana as affected by inorganic nitrogen in pot experiments with peat

1983 ◽  
Vol 61 (11) ◽  
pp. 2956-2963 ◽  
Author(s):  
U. Granhall ◽  
T. Ericsson ◽  
M. Clarholm
Keyword(s):  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Experimental Period ◽  
Alnus Incana ◽  
Nitrogen Application ◽  
Noticeable Effect ◽  
Essential Nutrients ◽  
Pot Experiments ◽  
Ph Level

The effects of single large or repeated, exponentially increasing applications of nutrients, with or without inorganic nitrogen and at two pH levels, on the growth, nodulation, acetylene reduction, and nutrient uptake in Alnus incana (L.) Moench were investigated in pot experiments with peat under controlled laboratory conditions. The repeated application of inorganic nitrogen did not suppress nitrogenase activity until the last 2 weeks, whereas an initial, large, nitrogen application effectively inhibited nodulation and activity throughout the 40-day experimental period. The mode of nitrogen application was thus found to be more important than the total amounts applied. Shoot length, leaf area, shoot–root relations, dry-matter production, and nitrogen contents of plants were determined at the end of the experiment, as well as the effect of Frankia inoculations. Nitrogenase activity was determined three times, at 0, 3, and 5 weeks. N2 fixation (balance/acetylene reduction) was found to be maximal, 55% of total nitrogen uptake, in minus-N pots with single applications of essential nutrients. The fastest growth was, however, noted in pots with single applications of all nutrients, including N. Among the latter, pots inoculated with Frankia showed the best growth, in spite of low nitrogenase activity. The only noticeable effect of a raised pH level was a reduced endophyte activity in minus-N pots with single applications of essential nutrients, due to increased N mineralization in the peat.

scholarly journals Alterations in microbial community composition with increasing <i>f</i>CO<sub>2</sub>: a mesocosm study in the eastern Baltic Sea

2017 ◽  
Vol 14 (16) ◽  
pp. 3831-3849 ◽  
Author(s):  
Katharine J. Crawfurd ◽  
Santiago Alvarez-Fernandez ◽  
Kristina D. A. Mojica ◽  
Ulf Riebesell ◽  
Corina P. D. Brussaard
Keyword(s):  
Microbial Community ◽  
Ocean Acidification ◽  
Baltic Sea ◽  
Community Dynamics ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
Cell Diameter ◽  
Viral Lysis ◽  
Nitrogen And Phosphorus ◽  
Eastern Baltic

Abstract. Ocean acidification resulting from the uptake of anthropogenic carbon dioxide (CO2) by the ocean is considered a major threat to marine ecosystems. Here we examined the effects of ocean acidification on microbial community dynamics in the eastern Baltic Sea during the summer of 2012 when inorganic nitrogen and phosphorus were strongly depleted. Large-volume in situ mesocosms were employed to mimic present, future and far future CO2 scenarios. All six groups of phytoplankton enumerated by flow cytometry ( <  20 µm cell diameter) showed distinct trends in net growth and abundance with CO2 enrichment. The picoeukaryotic phytoplankton groups Pico-I and Pico-II displayed enhanced abundances, whilst Pico-III, Synechococcus and the nanoeukaryotic phytoplankton groups were negatively affected by elevated fugacity of CO2 (fCO2). Specifically, the numerically dominant eukaryote, Pico-I, demonstrated increases in gross growth rate with increasing fCO2 sufficient to double its abundance. The dynamics of the prokaryote community closely followed trends in total algal biomass despite differential effects of fCO2 on algal groups. Similarly, viral abundances corresponded to prokaryotic host population dynamics. Viral lysis and grazing were both important in controlling microbial abundances. Overall our results point to a shift, with increasing fCO2, towards a more regenerative system with production dominated by small picoeukaryotic phytoplankton.

scholarly journals TO THE QUESTION OF COMPREHENSIVE ASSESSMENT OF SURFACE WATER IN THE CENTRAL CAUCASUS DURING WINTER BETWEEN AND SUMMER FLOOD

2021 ◽  
Vol 6 (5(55)) ◽  
pp. 22-27
Author(s):  
Liliya Zuberovna Zhinzhakova ◽  
Elena Alexandrovna Cherednik
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Inorganic Nitrogen ◽  
High Water ◽  
Polluted Water ◽  
Trace Impurities ◽  
Central Caucasus ◽  
Summer Flood

Based on long-term observations, the assessment of the pollution of the rivers of the Central Caucasus was carried out by comparing the calculated coefficients of the complexity of pollution and the specific combinatorial index of pollution of surface waters, and the quality classes were determined. The results of chemical analysis of the concentration levels of trace impurities (Mo, Pb, Zn, V, Ni, Cr, Mn, Ag) and inorganic nitrogen compounds (NO2 -, NO3 — and NH4 +) in the waters of 13 rivers in two permanent sections of each watercourse were used. The results of calculating the indicators of pollution in the waters of rivers of winter low water and summer high water are presented. The most polluted watercourses and the frequency of pollution in each river are identified, estimated by the values of the specific combinatorial index of water pollution, the coefficient of complexity of pollution, and the class of water quality is presented. The assessment of the most polluted water bodies during the winter low-water period and summer flood is given according to the classification of water quality. According to long-term observations, the features of watercourses and their differences in terms of pollution are presented.

scholarly journals Lake sedimentary DNA to reveal long-term changes in aquatic biodiversity and ecosystem functioning

2021 ◽  
Vol 4 ◽  
Author(s):  
Isabelle Domaizon
Keyword(s):  
Community Dynamics ◽  
Temporal Dynamics ◽  
Critical Research ◽  
Aquatic Biodiversity ◽  
Biological Variables ◽  
Long Term Changes ◽  
Research Questions ◽  
Population And Community Dynamics ◽  
Emerging Topics

The emergence of molecular analyses based on the sequencing of sedimentary DNA has opened up many new areas of inquiry in paleolimnology. DNA preserved in sediments (SedDNA) offers the possibility to consider taxa that were traditionally not accessible because they do not leave distinct morphological fossils. Recent applications that considered a diversity of biological groups (including bacteria, protists, zooplankton, fish) illustrate how efficiently SedDNA-based methods complement both classical paleolimnology proxies and limnological data. The knowledge gained from this approach is very diverse in scope, ranging from quantifying natural variability in population and community dynamics to understanding how these biological variables respond to anthropogenic disturbances and climatic change. The use of lake sedimentary DNA to track long-term changes in aquatic biota is a rapidly advancing field of research. Based on recent applications, this presentation illustrates (i) the potential and challenges associated with the study of SedDNA to address critical research questions in lacustrine ecology (ii) the main methodological precautions to be taken into account for implementing these types of DNA analyses (i.e. best practices) and (iii) the emerging topics that could be addressed using sedimentary DNA, in particular to reconstruct the temporal dynamics of lacustrine biodiversity.

Initial studies of the growth, nitrogen sequestering, and de-watering potential of perennial grass selections for use as nitrogen catch crops in orchards

2003 ◽  
Vol 54 (1) ◽  
pp. 27 ◽  
Author(s):  
P. R. Stork ◽  
P. H. Jerie
Keyword(s):  
Open Field ◽  
Festuca Arundinacea ◽  
Inorganic Nitrogen ◽  
Perennial Grass ◽  
Fruit Trees ◽  
High Water ◽  
Field Trials ◽  
Growth Cycle ◽  
Perennial Grasses ◽  
Leaching Losses

Two field trials were established to evaluate the ability of perennial grasses to recoup leaching losses of nitrogen in orchards. A perennial grass was considered suitable for use in orchards if it had a winter active–summer dormant growth cycle. High winter growth would ensure de-watering of the soil profile and nitrate uptake during this period, when an orchard is most vulnerable to leaching losses of nitrate. Low growth in summer would minimise competition for water and nutrients with fruit trees. These traits were studied in 14 varieties of grasses from 8 species in an open field and in an established apricot orchard. Semi-dormant summer growth was observed in species such as Dactylis glomerata L. cv. Kasbah, and Festuca arundinacea L. cv. MK88931. In the open field trial, the sequestration of NO3–-N + NH4+-N between late autumn and early spring, by Kasbah and MK88931, was estimated at 172 and 220 kg N/ha, respectively. Kasbah and MK88931 also demonstrated the driest soil profiles to a depth of 1.5 m in this period. This reflected their high water use and de-watering potential. Therefore, the performance of these grasses demonstrated a model approach to mitigate nitrate leaching below orchard root-zones. They could minimise deep percolation of rainfall and sequestered large amounts of inorganic nitrogen in soil during winter, whilst producing low growth during summer.

scholarly journals Phytoplankton Biomass Dynamics in Tropical Coastal Waters of Jakarta Bay, Indonesia in the Period between 2001 and 2019

2020 ◽  
Vol 8 (9) ◽  
pp. 674 ◽  
Author(s):  
Ario Damar ◽  
Franciscus Colijn ◽  
Karl-Juergen Hesse ◽  
Luky Adrianto ◽  
Yonvitner ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Temporal Dynamics ◽  
Inorganic Nitrogen ◽  
Outer Part ◽  
Middle Part ◽  
Nutrient Concentrations ◽  
Marine Biota ◽  
Chl A ◽  
Hypoxic Conditions

A study of nutrients, underwater light dynamics, and their correlation with phytoplankton biomass was conducted in the tropical estuary of Jakarta Bay, Indonesia, in the dry season during the period from 2001 to 2019. This study analyzed the spatial and temporal dynamics of phytoplankton biomass and its correlation with phytoplankton biomass. There was significant increase in nutrient concentration in Jakarta Bay, with annual means of 27.97 µM dissolved inorganic nitrogen (DIN) and 11.31 µM phosphates in 2001, increasing to 88.99 µM DIN and 25.92 µM phosphates in 2019. Increased mean nutrient concentrations were accompanied by increased mean phytoplankton biomass, from 15.81 µg Chl-a L−1 in 2001 to 21.31 µg Chl-a L−1 in 2019. The eutrophication status of Jakarta Bay waters was calculated using the Tropical Index for Marine Systems eutrophication index, which showed increased areas of hyper-eutrophic and eutrophic zones, while the mesotrophic area decreased. The hyper-eutrophic zone dominated the areas around river mouths and the inner part of the bay, while eutrophic status was observed in the middle part of the bay and mesotrophic status was found in the outer part of the bay. The area of hyper-eutrophic water increased 1.5-fold, from 75.1 km2 in 2001 to 114.0 km2 in 2019. Increasing eutrophication of the bay has had negative ecological consequences including algal blooms, hypoxic conditions, and mass mortality of marine biota, and it urgently requires remediation.

Seasonal succession of diatom epiphyton on dense mats of Lemna minor

1985 ◽  
Vol 63 (12) ◽  
pp. 2332-2339 ◽  
Author(s):  
L. G. Goldsborough ◽  
G. G. C. Robinson
Keyword(s):  
Lemna Minor ◽  
Algal Growth ◽  
Seasonal Succession ◽  
Ambient Air ◽  
Early Spring ◽  
Early Summer ◽  
Algal Community ◽  
Light Limitation ◽  
Total Biomass

Annual sequences of biomass, species diversity, and community composition of epiphytic diatoms on a dense mat of Lemna minor L. growing in a freshwater marsh are described. In 2 successive years, maximum biomass occurred in early spring prior to occlusion of the water surface by the mat, while diversity reached relative maxima in the early summer (during a period of declining total biomass) and late fall. Ambient air temperature (possibly through a relationship with in situ metabolic activity and nutrient availability) was significantly correlated with community ordination scores on a temporal basis. Depth profile maxima of diatom abundance on vertically positioned artificial substrata occurred below the mat, suggesting that light limitation of algal growth within dense mats may be of lesser importance. Dominant diatom species in the spring and fall were generally ubiquitous in the surrounding marsh, while the major taxa in midsummer, Achnanthes hungarica, Amphora veneta, and Navicula twymaniana, may be specific to the Lemna microhabitat. The development of algal community specificity within a defined seasonal range is discussed in terms of the relative importance of host exudates versus exogenous nutrients as the basis for algal-substratum associations.

Impacts of Lythrum salicaria invasion on plant community and soil properties in two wetlands in central New York, USA

2006 ◽  
Vol 84 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Wendy M. Mahaney ◽  
Kurt A. Smemo ◽  
Joseph B. Yavitt
Keyword(s):  
New York ◽  
Soil Properties ◽  
Aboveground Biomass ◽  
Native Species ◽  
Community Dynamics ◽  
Inorganic Nitrogen ◽  
New York State ◽  
Lythrum Salicaria ◽  
Agricultural Field ◽  
Central New York

While the spread of the exotic Lythrum salicaria L. across wetlands in North America is thought to negatively affect the performance and diversity of native species, the actual impacts of L. salicaria invasion on community dynamics and ecosystem properties are not well understood. To determine whether L. salicaria affects community aboveground biomass, native species biomass, or soil properties, we studied two common situations in central New York State where L. salicaria invaded (i) an abandoned agricultural field and (ii) a relatively pristine wetland with low species diversity. In the agricultural site, nearly monospecific stands of L. salicaria and Phalaris arundinacea L. had nearly identical shoot mass (approx. 850 g·m–2) but divergent soil characteristics. Inorganic nitrogen was significantly higher under L. salicaria than under P. arundinacea. The low-diversity site is dominated by Carex lacustris Willd., with distinct areas codominated by either L. salicaria or Typha latifolia L. In this site, we found that areas with a codominant species had significantly more total aboveground biomass than those dominated by C. lacustris, suggesting that L. salicaria invasion does not significantly lower native species biomass. However, most soil nutrient levels did not differ among vegetation zones, indicating that species composition changes did not alter soil properties in the short term. This study supports a growing literature suggesting that L. salicaria invasion may not negatively impact relatively pristine wetlands as previously believed.

Dynamique d'une bordure forestière et variations récentes du niveau du fleuveSaint-Laurent

1988 ◽  
Vol 66 (10) ◽  
pp. 1905-1913 ◽  
Author(s):  
Yves Bégin ◽  
Jean Lavoie
Keyword(s):  
Plant Community ◽  
Woody Plants ◽  
Community Dynamics ◽  
Direct Evidence ◽  
Ring Width ◽  
High Water ◽  
Water Levels ◽  
Exposed Site ◽  
Plant Community Dynamics ◽  
Saint Lawrence River

The forested shoreline of the Saint Lawrence River upper estuary is frequently damaged by spring ice, currents, and waves during episodes of high water levels. A dendroecological analysis of the significant river floods, as recorded by ring-width patterns of uprooted woody plants, population growth and decay structures, and scars caused by ice on trees within the shore environment, provides direct evidence of a landward migrating shoreline. Regressive succession of vegetation is associated with a general rise in year-to-year flood levels. Plant community dynamics and shore sediment migration were investigated in a particularly exposed site between Grondines and Sainte-Anne-de-la-Pérade. Most of the oldest sublittoral trees are undergoing slow degradation and hydrophilous shrubby stands show extensive expansion within the shoreline habitat, which is associated with an important landward displacement of sediments. These ecological and geomorphological results concur with the general rising trend of flood levels of the Saint Lawrence during the last 30 years.

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