High nutrient availability leads to weaker top-down control of stream periphyton: Compensatory feeding in Ancylus fluviatilis

2018 ◽  
Vol 64 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Alessandra Iannino ◽  
Alexander T. L. Vosshage ◽  
Markus Weitere ◽  
Patrick Fink
Keyword(s):  
Nutrient Availability ◽  
Top Down ◽  
Compensatory Feeding ◽  
Stream Periphyton ◽  
High Nutrient

scholarly journals Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1682
Author(s):  
Yoonja Kang ◽  
Yeongji Oh
Keyword(s):  
Nutrient Availability ◽  
Fast Response ◽  
Nutrient Addition ◽  
The Other ◽  
Zooplankton Grazing ◽  
Top Down ◽  
Bottom Up ◽  
Phytoplankton Distribution ◽  
Summer Bloom ◽  
Gwangyang Bay

The interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determined by flow cytometry, were examined in association with zooplankton grazing and nutrient availability. The summer bloom was attributed to nanoplankton, and microplankton was largely responsible for the winter bloom, whereas the picoplankton biomass was relatively consistent throughout the sampling periods, except for the fall. The nutrient addition experiments illustrated that nanoplankton responded more quickly to phosphate than the other groups in the summer, whereas microplankton had a faster response to most nutrients in the winter. The dilution experiments ascribed that the grazing mortality rates of eukaryotes were low compared to those of the other groups, whereas autotrophic cyanobacteria were more palatable to zooplankton than cryptophytes and eukaryotes. Our experimental results indicate that efficient escape from zooplankton grazing and fast response to nutrient availability synergistically caused the microplankton to bloom in the winter, whereas the bottom-up process (i.e., the phosphate effect) largely governed the nanoplankton bloom in the summer.

scholarly journals Relationship between Bacterial Community Composition and Bottom-Up versus Top-Down Variables in Four Eutrophic Shallow Lakes

2002 ◽  
Vol 68 (10) ◽  
pp. 4740-4750 ◽  
Author(s):  
Koenraad Muylaert ◽  
Katleen Van der Gucht ◽  
Nele Vloemans ◽  
Luc De Meester ◽  
Moniek Gillis ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Shallow Lakes ◽  
Bacterial Community Composition ◽  
Top Down ◽  
Bottom Up ◽  
Rdna Genes ◽  
Explanatory Variables ◽  
High Nutrient ◽  
Eutrophic Shallow Lakes

ABSTRACT Bacterial community composition was monitored in four shallow eutrophic lakes during one year using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified prokaryotic rDNA genes. Of the four lakes investigated, two were of the clearwater type and had dense stands of submerged macrophytes while two others were of the turbid type characterized by the occurrence of phytoplankton blooms. One turbid and one clearwater lake had high nutrient levels (total phosphorus, >100 μg liter−1) while the other lakes had relatively low nutrient levels (total phosphorus, <100 μg liter−1). For each lake, seasonal changes in the bacterial community were related to bottom-up (resources) and top-down (grazers) variables by using canonical correspondence analysis (CCA). Using an artificial model dataset to which potential sources of error associated with the use of relative band intensities in DGGE analysis were added, we found that preferential amplification of certain rDNA genes over others does not obscure the relationship between bacterial community composition and explanatory variables. Besides, using this artificial dataset as well as our own data, we found a better correlation between bacterial community composition and explanatory variables by using relative band intensities compared to using presence/absence data. While bacterial community composition was related to phytoplankton biomass in the high-nutrient lakes no such relation was found in the low-nutrient lakes, where the bacterial community is probably dependent on other organic matter sources. We used variation partitioning to evaluate top-down regulation of bacterial community composition after bottom-up regulation has been accounted for. Using this approach, we found no evidence for top-down regulation of bacterial community composition in the turbid lakes, while grazing by ciliates and daphnids (Daphnia and Ceriodaphnia) was significantly related to changes in the bacterial community in the clearwater lakes. Our results suggest that in eutrophic shallow lakes, seasonality of bacterial community structure is dependent on the dominant substrate source as well as on the food web structure.

scholarly journals Apical leaf necrosis as a defence mechanism against pathogen attack: effects of high nutrient availability on onset and rate of necrosis

2008 ◽  
Vol 57 (6) ◽  
pp. 1009-1016 ◽  
Author(s):  
F. van den Berg ◽  
F. van den Bosch ◽  
S. J. Powers ◽  
M. W. Shaw
Keyword(s):  
Nutrient Availability ◽  
Defence Mechanism ◽  
High Nutrient ◽  
Apical Leaf ◽  
Leaf Necrosis ◽  
Pathogen Attack

scholarly journals Phytoplankton dynamics in relation to environmental changes in a phytoplankton-dominated Mediterranean lagoon (Cabras Lagoon, Italy)

2012 ◽  
Vol 3 (2) ◽  
pp. 147 ◽  
Author(s):  
B.M. Padedda ◽  
S. Pulina ◽  
P. Magni ◽  
N. Sechi ◽  
A. Lugliè
Keyword(s):  
Nutrient Availability ◽  
Environmental Changes ◽  
Negative Impact ◽  
Inorganic Nitrogen ◽  
Algal Species ◽  
Temporal Variations ◽  
Extreme Weather Events ◽  
Economic Activities ◽  
Phytoplankton Assemblages ◽  
High Nutrient

In Mediterranean lagoons, macrophytes often surpass phytoplankton as the most important primary producers. Less frequently, phytoplankton dominates throughout the year, thus knowledge of its dynamics is relatively limited and scattered. In this study, we assessed over two years the dynamics of phytoplankton assemblages, including potential harmful algal species (HAS), in relation to environmental changes in the phytoplankton-dominated Cabras Lagoon (Sardinia, Italy). The lagoon was characterised by uniform spatial conditions, wide temporal variations in salinity (40 PSU) and high nutrient availability. Phosphorus was highest in summer, possibly recycled within the system, while dissolved inorganic nitrogen increased in winter and spring due to watershed discharge. Chlorophyll a, positively correlated with nutrients and rainfall, showed a typical bimodal pattern with summer-winter blooms. Modifications in phytoplankton composition strongly correlated with extreme weather events, such as intense rainfall. This generated an abrupt salinity decrease that, combined with high nutrient availability, favoured the dominance of Cyanophyceae of reduced cell size, such as Cyanobium and Rhabdoderma species. We suggest that the prolonged and intense dominance of Cyanophyceae, added to other HAS, has a negative impact on the primary economic activities of the lagoon, such as fishery, and generally on the whole lagoon functioning.

scholarly journals Plant flexible stoichiometry and herbivore compensatory feeding drive population dynamics across temperature and nutrient gradients

2021 ◽  
Author(s):  
Jori Marx ◽  
Ulrich Brose ◽  
Angélica Gonzalez ◽  
Benoit Gauzens
Keyword(s):  
Population Dynamics ◽  
Nutrient Availability ◽  
Nutrient Content ◽  
Temperature Threshold ◽  
Feeding Rates ◽  
Higher Plant ◽  
Substantial Impact ◽  
Compensatory Feeding ◽  
Modelling Studies ◽  
Lower Temperature

Global change drivers like warming and changing nutrient cycles have a substantial impact on ecosystem functioning. In most modelling studies, organism responses to warming are described through the temperature dependence of their biological rates. In nature, however, organisms are more than their biological rates. Plants are flexible in their elemental composition (stoichiometry) and respond to variance in nutrient availability and temperature. An increase in plant carbon-to-nutrient content means a decrease in food quality for herbivores. Herbivores can react to this decrease by compensatory feeding, which implies higher feeding rates and higher carbon excretion to optimize nutrient acquisition. In a novel model of a nutrient-plant-herbivore system, we explored the consequences of flexible stoichiometry and compensatory feeding for plant and herbivore biomass production and survival across gradients in temperature and nutrient availability. We found that flexible stoichiometry increases plant and herbivore biomasses, which results from increased food availability due to higher plant growth. Surprisingly, compensatory feeding decreased plant and herbivore biomasses as overfeeding by the herbivore reduced plants to low densities and depleted their resource. Across a temperature gradient, compensatory feeding caused herbivore extinction at a lower temperature, while flexible stoichiometry increased its extinction threshold. Our results suggest that compensatory feeding can become critical under warm conditions. In contrast, flexible stoichiometry is beneficial for plants up to a certain temperature threshold. These findings demonstrate the importance of accounting for adaptive and behavioural organismal responses to nutrient and temperature gradients when predicting the consequences of warming and eutrophication for population dynamics and survival.

scholarly journals Soil microbes mediate the effects of environmental variability on plant invasion

2021 ◽  
Author(s):  
Xue Zhang ◽  
Mark van Kleunen ◽  
Chunling Chang ◽  
Yanjie Liu
Keyword(s):  
Nutrient Availability ◽  
Plant Invasion ◽  
Environmental Variability ◽  
Soil Analysis ◽  
Soil Microbial Communities ◽  
Soil Nutrient ◽  
Opposite Pattern ◽  
Native Communities ◽  
Soil Microbial ◽  
High Nutrient

Many studies indicate that increases in resource variability promote plant invasion. However, it remains unknown to what extent these effects might indirectly be mediated by other organisms. To test this, we grew eight alien species in pot-mesocosms with five different native communities under eight combinations of two nutrient-availability, two nutrient-fluctuation and two soil-microbe treatments. We found that when plants grew in sterilized soil, nutrient fluctuation promoted the dominance of alien plants under low nutrient availability, whereas its effect was minimal under high nutrient availability. However, the opposite pattern was found when plants grew in living soil. Analysis of the soil microbial community suggests that this might reflect that nutrient fluctuation strongly increased the soil fungal pathogen diversity under high nutrient availability, but slightly decreased it under low nutrient availability. Our findings indicate that besides its direct influence, environmental variability could also indirectly affect plant invasion via changes in soil-microbial communities.

Plant Nutrient Relations

2001 ◽  
Author(s):  
Russell K. Monson ◽  
Renée Mullen
Keyword(s):  
Nutrient Availability ◽  
Inorganic Ions ◽  
Nutrient Utilization ◽  
Alpine Plants ◽  
Alpine Soils ◽  
P Acquisition ◽  
Long Term Storage ◽  
Nutrient Use ◽  
High Nutrient ◽  
Nutrient Relations

Alpine soils do not generally exhibit high levels of inorganic fertility, which is the result of inadequate mineralization of organic litter, a consequence of the cool, short alpine growing season (Rehder and Schäfer 1978; Gokceoglu and Rehder 1977; Rehder 1976a, 1976b; Fisk and Schmidt 1995; chapters 11, 12). Slow mineralization rates, in turn, result in a soil that is high in organic humus, and more likely than the soil of other ecosystems, to sequester and bind inorganic nutrients, especially N and P. Accordingly, alpine plants are exposed to a difficult situation in their efforts to obtain the inorganic ions required to support growth and reproduction. In accommodating the relative infertility of alpine soils, plants rely on a number of different traits, some of which are ubiquitous and some of which are more restricted in their distribution. Biomass allocation patterns favor high root:shoot ratios, increasing the potential for nutrient absorption by the roots relative to nutrient utilization by the shoot. Nutrient-use efficiencies (biomass produced per mass of senescent nutrient) tend to be high in alpine plants due to efficient resorption prior to leaf senescence. In several alpine growth forms, strict internal controls over seasonal phenology and growth (e.g., preformed buds and strongly enforced dormancy patterns) bring growth demands for nutrients more into balance with the limited supply provided by the soil. Luxury uptake and long-term storage during pulses of high nutrient availability provide plants with a means of bridging the gap between incongruent periods of high nutrient supply and high nutrient demand. Association of fungi with the roots of some alpine plants has the potential to enhance N and P acquisition. Finally, some alpine species can overcome the limitations imposed by scarce inorganic nutrient supplies through high rates of organic nutrient assimilation. It is the aim of this chapter to further consider each of these traits, with particular emphasis on their relationship to N and P acquisition. Topics concerning soil processes and their role in controlling nutrient availability have been covered elsewhere (chapter 8) and will not be repeated. Rather, this review focuses on nutrient relations from the plant’s perspective.

The relationship between starch content in rhizomes of Phragmites australis (Cav.) Trin. ex Steud. and trophic conditions of habitat

1994 ◽  
Vol 102 ◽  
pp. 433-438 ◽  
Author(s):  
P. Kubin ◽  
A. Melzer ◽  
H. Čižkova
Keyword(s):  
Phragmites Australis ◽  
Nutrient Availability ◽  
Aboveground Biomass ◽  
Starch Content ◽  
Trophic Conditions ◽  
High Nutrient ◽  
One Year ◽  
Reed Decline ◽  
The Relationship

SynopsisThe hypothesis of reed decline being a consequence of eutrophication has been proved. Rhizomes of P. australis from two habitats differing in nutrient availability were collected during one year. In the nutrient-poor habitat, less aboveground biomass and greater starch reserves were formed in comparison with the nutrient-rich one. In the stand with a high nutrient availability, a decrease in starch content was observed in horizontal rhizomes during autumn.

Investigating the in-situ bacterial production of aquatic fluorescent organic matter using a freshwater laboratory model

2020 ◽  
Author(s):  
Eva Perrin ◽  
John Attridge ◽  
Robin Thorn ◽  
Stephanie Sargeant ◽  
Darren Reynolds
Keyword(s):  
Organic Matter ◽  
Nutrient Availability ◽  
Bacterial Production ◽  
Nutrient Loading ◽  
Laboratory Model ◽  
Freshwater Systems ◽  
Laboratory Conditions ◽  
Fluorescence Characteristics ◽  
High Nutrient

&lt;p&gt;This research explores the &lt;em&gt;in-situ&lt;/em&gt; bacterial production of aquatic fluorescent organic matter (AFOM) under controlled laboratory conditions. Whilst fluorescence techniques have long been used to monitor AFOM distribution, origin and dynamics within aquatic systems, the extent to which AFOM characteristics are defined by microbial processing in surface freshwaters has largely been overlooked. Current convention champions the assumption that humic-like (Peak C) and protein-like (Peak T) fluorescence signatures are exclusively derived from terrestrial (allochthonous) or microbial (autochthonous) origins respectively, with Peak T having been directly correlated with microbial enumeration. Under intensifying anthropogenic perturbations and changing catchment characteristics, the complexities associated with bacterial-organic matter (OM) interactions in freshwater systems are increasing, challenging our understanding as to the origin and fate of aquatic OM. To what extent the observed AFOM in freshwater systems is defined by bacterial processing and how such processing may be influenced by nutrient availability are key knowledge gaps that need to be addressed. Previous research has observed the &lt;em&gt;in-situ&lt;/em&gt; bacterial production of humic-like compounds in a laboratory model system with a high-nutrient and high-carbon content synthetic growth medium. This work describes a non-fluorescing, simulated freshwater matrix which is low in both nutrient and organic carbon concentrations. Using this model, growth curve incubation experiments have been undertaken over a 48-hour period with a monoculture laboratory strain of &lt;em&gt;Pseudomonas aeruginosa&lt;/em&gt;. Microbiological and fluorescence analyses undertaken at regular time intervals demonstrate the bacterial production of humic-like OM (Peak C) under oligotrophic (after 8hrs) and simulated high-nutrient conditions (after 6hrs). These findings, albeit under laboratory conditions, are important as they show that this fluorescence region, currently viewed as allochthonous in origin, can also represent labile OM generated &lt;em&gt;in-situ&lt;/em&gt; by bacteria and, furthermore, that this bacterial production increases as a function of nutrient loading. In addition, the data quantitatively demonstrates that fluorescence intensities increase independently of cell density. These results challenge the assumption that humic-like AFOM is exclusively terrestrial in origin and suggest that bacteria may &amp;#8220;engineer&amp;#8221; OM&lt;em&gt; in-situ&lt;/em&gt; that gives rise to these fluorescence characteristics as a function of metabolism. Importantly, nutrient availability is a key driver of metabolic activity, outlining the potential for the use of fluorescence as a marker for stream metabolism as opposed to a measure of bacterial numbers. Further development of the laboratory model via the utilisation of environmentally-sourced bacterial communities is required. Ultimately, this laboratory model will inform field studies that look to improve our understanding of how microbial communities respond to catchment stressors, and how these responses influence AFOM fluorescence signatures and ultimately the origin and fate of OM in freshwater systems.&lt;/p&gt;

scholarly journals Growth and photosynthesis responses of two co-occurring marsh grasses to inundation and varied nutrients

Botany ◽  
2015 ◽  
Vol 93 (10) ◽  
pp. 671-683 ◽  
Author(s):  
Elizabeth Burke Watson ◽  
Holly M. Andrews ◽  
Amy Fischer ◽  
Morgan Cencer ◽  
Laura Coiro ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Nutrient Availability ◽  
Tidal Marshes ◽  
Nutrient Loads ◽  
Nutrient Inputs ◽  
Nutrient Additions ◽  
High Nutrient ◽  
Us Northeast ◽  
Tiller Density

For tidal marshes of the US Northeast, the late twentieth century decline of Spartina patens (Aiton) Muhl. has been attributed to increased flooding associated with accelerated sea level rise and nitrogen over-enrichment from cultural eutrophication. The objective of this study was to examine the impacts of inundation and nutrient availability on growth, photosynthesis, and interactions of S. patens and Distichlis spicata (L.) Greene, which co-occur and are common marsh species. Plants were grown in a factorial greenhouse experiment, where flow-through seawater was used to simulate semidiurnal tides. Field surveys were additionally conducted to relate plant distributions to environmental conditions. For S. patens grown in monoculture, nutrient additions did not enhance growth for the high inundation treatment. In addition, the combination of high nutrient availability and high inundation adversely affected S. patens tiller density, photosynthetic efficiency, and leaf CO2 uptake. For D. spicata, nutrient additions enhanced growth for both inundation treatments with respect to aboveground biomass and tiller density. For species pairings, S. patens expanded relative to D. spicata under low inundation, low nutrient availability conditions, but declined relative to D. spicata under daily inundation in combination with nutrient amendments. These findings were additionally supported by field data, which indicated that D. spicata was more common than S. patens where nutrient availability was high. These results suggest that S. patens persistence is favored by low nutrient inputs and well-drained conditions, and supports the interpretation that this species is vulnerable to loss where high nutrient loads coincide with accelerated sea level rise.

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