Contribution by Macroalgal Mats to Primary Production of a Shallow Embayment Under High and Low Nitrogen-loading Rates

1996 ◽  
Vol 43 (3) ◽  
pp. 311-325 ◽  
Author(s):  
P. Peckol ◽  
J.S. Rivers
Keyword(s):  
Primary Production ◽  
Nitrogen Loading ◽  
Loading Rates ◽  
Low Nitrogen ◽  
Macroalgal Mats

Relationship Between N2-Fixation and Heterocyst Abundance and its Relevance to the Nitrogen Budget of Lake 227

1994 ◽  
Vol 51 (10) ◽  
pp. 2254-2266 ◽  
Author(s):  
D. L. Findlay ◽  
R. E. Hecky ◽  
L. L. Hendzel ◽  
M. P. Stainton ◽  
G. W. Regehr
Keyword(s):  
N:P Ratio ◽  
Molar Ratio ◽  
External Loading ◽  
N Fixation ◽  
Fixation Rate ◽  
Loading Rates ◽  
Relative Contribution ◽  
Cyanobacteria Blooms ◽  
N Loading ◽  
Low Nitrogen

A significant relationship between seasonal N2-fixation rate and heterocyst abundance has been found in Lake 227 and can be modelled to estimate areal rates of N2-fixation based on the known historical phytoplankton records. Experimental imposition of low nitrogen (N): phosphorus (P) loading ratios stimulated N,-fixation. The N:P molar ratio of the internal pool of nutrients oscillates around a mean of 30:1, despite experimental loading ratios that vary from 13:1 to 0. Maintenance of this internal nutrient mass ratio requires preferential regeneration of N through time at all loading rates. Heterocystous, cyanobacteria blooms are most predictable during imposition of a very low external loading N:P ratio and high P loading relative to natural sources. Knowledge of the internal loading N:P ratio and relative contribution of internal and external loadings are required for predicting blooms at intermediate external N:P loading rates. The internal N:P ratio has fluctuated within narrow limits over 25 yr of nearly constant P loading because of adjustments in N2-fixation, N sedimentation, and denitrification, which have counterbalanced changing experimental N loading regimes.

Metagenomics reveals microbial community differences lead to differential nitrate production in anammox reactors with differing nitrogen loading rates

2020 ◽  
Vol 169 ◽  
pp. 115279 ◽  
Author(s):  
Wei Li ◽  
Jin-long Zhuang ◽  
Yuan-yuan Zhou ◽  
Fan-gang Meng ◽  
Da Kang ◽  
...  
Keyword(s):  
Microbial Community ◽  
Nitrogen Loading ◽  
Loading Rates ◽  
Nitrate Production

Comparison of quasisteady-state performance of the DEAMOX process under intermittent and continuous feeding and different nitrogen loading rates

2007 ◽  
Vol 2 (7) ◽  
pp. 894-900 ◽  
Author(s):  
Sergey Kalyuzhnyi ◽  
Marina Gladchenko ◽  
Arnold Mulder ◽  
Bram Versprille
Keyword(s):  
Nitrogen Loading ◽  
Loading Rates ◽  
Continuous Feeding

Tolerance of the arctic graminoid Luzula arcuata ssp. confusa to simulated grazing in two nitrogen environments

2000 ◽  
Vol 78 (8) ◽  
pp. 1108-1113 ◽  
Author(s):  
Kari Anne Bråthen ◽  
Ann Marie Odasz-Albrigtsen
Keyword(s):  
Primary Production ◽  
No Reduction ◽  
Reproduction Number ◽  
Plant Traits ◽  
Net Primary Production ◽  
The Arctic ◽  
Growing Seasons ◽  
Simulated Grazing ◽  
Nitrogen Treatment ◽  
Low Nitrogen

We investigated the response of the important forage plant Luzula arcuata Swartz ssp. confusa (Lindeb.) Blytt to simulated grazing during two growing seasons in a phytotron. Plants were clipped at five levels of intensity and fertilized at two levels of nitrogen. There was no reduction in net primary production of clipped compared with unclipped plants after either of the two growing seasons. Such results indicate that L. arcuata ssp. confusa can compensate for defoliation. Plants overcompensated in net aboveground primary production (NAPP) in the first season and compensated in NAPP in the second season. Plant traits contributing to the compensation in NAPP were stimulation of tillering in clipped plants, increase in specific leaf area of the most heavily clipped plants, and a higher proportion of NAPP occurring below clipping height in frequently clipped plants. Sexual reproduction (number of flowering shoots) was enhanced in the second season in plants clipped at 6 cm above the soil and reduced in plants clipped 3 cm above the soil. The response to clipping was independent of nitrogen treatment, suggesting that nitrogen did not limit regrowth even in the low nitrogen environment. Luzula arcuata ssp. confusa is tolerant of dry, cold and windswept, low-nutrient habitats in the Arctic. This study shows that it also is tolerant of defoliation.Key words: forage, herbivory, compensation, grazing responses, Svalbard.

scholarly journals Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

2017 ◽  
Vol 14 (19) ◽  
pp. 4423-4433 ◽  
Author(s):  
Yafei Zhu ◽  
Andrew McCowan ◽  
Perran L. M. Cook
Keyword(s):  
Water Quality ◽  
Primary Production ◽  
Total Phosphorus ◽  
Coastal Lagoon ◽  
Nutrient Dynamics ◽  
Nutrient Loading ◽  
Nitrogen Loading ◽  
Quality Model ◽  
Nitrogen Loads ◽  
Sediment Carbon

Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

Abundance, Biomass, and Species Richness of Fish Communities in Relation to Nitrogen-Loading Rates of Waquoit Bay Estuaries

1996 ◽  
Vol 191 (2) ◽  
pp. 321-322 ◽  
Author(s):  
J. Tober ◽  
C. Fritz ◽  
E. LaBrecque ◽  
P. J. Behr ◽  
I. Valiela
Keyword(s):  
Species Richness ◽  
Fish Communities ◽  
Nitrogen Loading ◽  
Loading Rates ◽  
Waquoit Bay
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