scholarly journals Nitrogen fixation does not axiomatically lead to phosphorus limitation in aquatic ecosystems

Oikos ◽  
2018 ◽  
Vol 128 (4) ◽  
pp. 563-570 ◽  
Author(s):  
Luuk P. A. van Gerven ◽  
Jan J. Kuiper ◽  
Wolf M. Mooij ◽  
Jan H. Janse ◽  
Hans W. Paerl ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Aquatic Ecosystems ◽  
Phosphorus Limitation

scholarly journals Cyano-assassins: Widespread cyanogenic production from cyanobacteria

2020 ◽  
Author(s):  
Manthos Panou ◽  
Spyros Gkelis
Keyword(s):  
Nitrogen Fixation ◽  
Secondary Metabolism ◽  
Hydrogen Cyanide ◽  
Aquatic Ecosystems ◽  
Study Material ◽  
Universal Representation

AbstractCyanobacteria have been linked with hydrogen cyanide, based on their ability to catabolize it by the nitrogenase enzyme, as a part of nitrogen fixation. Nitrogenase can also use hydrogen cyanide instead of its normal substrate, dinitrogen and convert it to methane and ammonia. In this study, we tested whether cyanobacteria are able, not only to reduce, but also to produce HCN. The production of HCN was examined in 78 cyanobacteria strains from all five principal sections of cyanobacteria, both non-heterocytous and heterocytous, representing a variety of lifestyles and habitats. Twenty-eight (28) strains were found positive for HCN production, with universal representation amongst 22 cyanobacterial planktic and epilithic genera inhabiting freshwater, brackish, marine (including sponges), and terrestrial (including anchialine) habitats. The HCN production could be linked with nitrogen fixation, as all of HCN producing strains are considered capable of fixing nitrogen. Epilithic lifestyle, where cyanobacteria are more vulnerable to a number of grazers and accumulate more glycine, had the largest percentage (75%) of HCN-producing cyanobacteria compared to strains from aquatic ecosystems. Further, we demonstrate the isolation and characterisation of taxa like Geitleria calcarea and Kovacikia muscicola, for which no strain existed and Chlorogloea sp. TAU-MAC 0618 which is, to the best of our knowledge, the first bacterium isolate from anchialine ecosystems. Our results highlight the complexity of cyanobacteria secondary metabolism, as well as the diversity of cyanobacteria in underexplored habitats, providing a missing study material for this type of environments.

Nitrogen Fixation in Aquatic Ecosystems

1990 ◽  
pp. 147-162
Author(s):  
Janet I. Sprent ◽  
Peter Sprent
Keyword(s):  
Nitrogen Fixation ◽  
Aquatic Ecosystems

Molybdenum and phosphorus limitation of moss-associated nitrogen fixation in boreal ecosystems

2016 ◽  
Vol 214 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Kathrin Rousk ◽  
Jefferson Degboe ◽  
Anders Michelsen ◽  
Robert Bradley ◽  
Jean-Philippe Bellenger
Keyword(s):  
Nitrogen Fixation ◽  
Phosphorus Limitation ◽  
Boreal Ecosystems

scholarly journals The Individual and Combined Effects of the Cyanotoxins, Anatoxin-a and Microcystin-LR, on the Growth, Toxin Production, and Nitrogen Fixation of Prokaryotic and Eukaryotic Algae

Toxins ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 43 ◽  
Author(s):  
Mathias Chia ◽  
Benjamin Kramer ◽  
Jennifer Jankowiak ◽  
Maria Bittencourt-Oliveira ◽  
Christopher Gobler
Keyword(s):  
Nitrogen Fixation ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Quantum Efficiency ◽  
Aquatic Ecosystems ◽  
Cyanobacterial Blooms ◽  
Combined Effects ◽  
Phytoplankton Communities ◽  
The Individual ◽  
Maximum Quantum Efficiency

Globally, eutrophication and warming of aquatic ecosystems has increased the frequency and intensity of cyanobacterial blooms and their associated toxins, with the simultaneous detection of multiple cyanotoxins often occurring. Despite the co-occurrence of cyanotoxins such as microcystins and anatoxin-a (ATX) in water bodies, their effects on phytoplankton communities are poorly understood. The individual and combined effects of microcystin-LR (MC-LR) and ATX on the cyanobacteria Microcystis spp., and Anabaena variabilis (a.k.a. Trichormus variabilis), and the chlorophyte, Selenastrum capricornutum were investigated in the present study. Cell density, chlorophyll-a content, and the maximum quantum efficiency of photosystem II (Fv/Fm) of Microcystis cells were generally lowered after exposure to ATX or MC-LR, while the combined treatment with MC-LR and ATX synergistically reduced the chlorophyll-a concentration of Microcystis strain LE-3. Intracellular levels of microcystin in Microcystis LE-3 significantly increased following exposure to MC-LR + ATX. The maximum quantum efficiency of photosystem II of Anabaena strain UTEX B377 declined during exposure to the cyanotoxins. Nitrogen fixation by Anabaena UTEX B377 was significantly inhibited by exposure to ATX, but was unaffected by MC-LR. In contrast, the combination of both cyanotoxins (MC-LR + ATX) caused a synergistic increase in the growth of S. capricornutum. While the toxins caused an increase in the activity of enzymes that scavenge reactive oxygen species in cyanobacteria, enzyme activity was unchanged or decreased in S. capricornutum. Collectively this study demonstrates that MC-LR and ATX can selectively promote and inhibit the growth and performance of green algae and cyanobacteria, respectively, and that the combined effect of these cyanotoxins was often more intense than their individual effects on some strains. This suggests that the release of multiple cyanotoxins in aquatic ecosystems, following the collapse of blooms, may influence the succession of plankton communities.

Phosphorus limitation on nitrogen fixation by Facaltaria seedlings

2003 ◽  
Vol 186 (1-3) ◽  
pp. 171-176 ◽  
Author(s):  
Dan Binkley ◽  
Randy Senock ◽  
Kermit Cromack
Keyword(s):  
Nitrogen Fixation ◽  
Phosphorus Limitation

scholarly journals Nitrogen fluxes in Western streams

2017 ◽  
Vol 40 ◽  
pp. 61-68
Author(s):  
Hilary L. Madinger ◽  
Robert O. Hall Jr.
Keyword(s):  
Nitrogen Fixation ◽  
Primary Production ◽  
Aquatic Ecosystems ◽  
Additional Data ◽  
Gross Primary Production ◽  
Dissolved Gas ◽  
Dissolved Nitrogen ◽  
Relationship Types ◽  
Stream Nitrate ◽  
The Relationship

Nitrogen pollution to streams is altering the nitrogen cycling in unknown ways, causing challenges for predicting nitrogen fixation fluxes within aquatic ecosystems. Increasing nitrate pollution decreases the amount of nitrogen fixation occurring in streams. However, the relationship between stream nitrate concentration and the rate of nitrogen fixation is unknown. We predict that lower nitrate streams will have the highest rates of nitrogen fixation. Additionally, there will be much more energy produced in streams with nitrogen fixation compared to the amount required to fix the nitrogen. We estimated whole-stream gross primary production and nitrogen fixation fluxes using the diel change in dissolved nitrogen and oxygen gases compared to the expected dissolved gas saturation. Our whole-stream method is preferable to chamber estimates to understand the relationship between energy requirements for nitrogen fixation and gross primary production, but additional data is needed to distinguish between relationship types and make our measurements generalizable.   Featured photo by Intermountain Forest Service, USDA Region 4 Photography on Flickr. https://flic.kr/p/jbTRUj

scholarly journals A novel Ca2+ signalling pathway co-ordinates environmental phosphorus sensing and nitrogen metabolism in marine diatoms

2020 ◽  
Author(s):  
K. E. Helliwell ◽  
E. Harrison ◽  
J. Christie-Oleza ◽  
A. P. Rees ◽  
J. Downe ◽  
...  
Keyword(s):  
Aquatic Ecosystems ◽  
Carbon Fixation ◽  
Resource Competition ◽  
Phosphorus Limitation ◽  
Nutrient Sensing ◽  
Signalling Pathway ◽  
Photosynthetic Eukaryotes ◽  
Highly Sensitive ◽  
Sense And Respond ◽  
Phytoplankton Group

AbstractDiatoms are a diverse and globally important phytoplankton group, responsible for an estimated 20% of carbon fixation on Earth. They frequently form spatially extensive phytoplankton blooms, responding rapidly to increased availability of nutrients including phosphorus and nitrogen. Although it is well established that diatoms are common first-responders to nutrient influxes in aquatic ecosystems, little is known of the sensory mechanisms that they employ for nutrient perception. Here we show that diatoms use a novel and highly-sensitive Ca2+-dependent signalling pathway, not previously described in eukaryotes, to sense and respond to the critical macronutrient phosphorus. We demonstrate that phosphorus-Ca2+ signalling is essential for regulating diatom recovery from phosphorus limitation, by controlling rapid and substantial increases in nitrogen assimilation. Phosphorus-Ca2+ signalling thus mediates fundamental cross-talk between the vital nutrients P and N to maximise resource competition, and likely governs the success of diatoms as major bloom formers in regions of pulsed nutrient supply. Importantly, our study demonstrates that distinct mechanisms for nutrient sensing have evolved in photosynthetic eukaryotes.

Comparison of the biogeochemistry of lakes and estuaries: ecosystem processes, functional groups, hysteresis effects and interactions between macro- and microbiology

1999 ◽  
Author(s):  
Graham P. Harris
Keyword(s):  
Functional Groups ◽  
Aquatic Ecosystems ◽  
Ecosystem Processes ◽  
Phosphorus Limitation ◽  
Nitrogen And Phosphorus ◽  
Marine Systems ◽  
Minor Elements ◽  
Water Flows ◽  
Global Patterns ◽  
Nitrogen Phosphorus

This paper reviews the biogeochemistry of carbon, nitrogen, phosphorus and their associated minor elements (iron and sulfur) in rivers, lakes and estuaries. The biogeochemistry of these elements can be explained by the physiology and stoichiometry of the major functional groups of micro- and macro-biota in these ecosystems. Furthermore, the global patterns of nitrogen and phosphorus limitation in freshwater and marine systems are explicable in terms of evolutionary differences between the major functional groups in freshwater and marine ecosystems, and their physiology and stoichiometry, as well as the interactions of carbon, iron, water residence times and ionic strength as the water flows from catchments to the sea. The highly non-linear responses of aquatic ecosystems to changing catchment loads of major and minor elements are explained by the interactions of the major functional groups and by competition between the pelagic and the benthos for nutrients and light.

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