scholarly journals Population dynamics and net primary production of the aquatic macrophite Nymphaea rudgeana C. F. Mey in a lotic environment of the Itanhaém River basin (SP, Brazil)

2000 ◽  
Vol 60 (1) ◽  
pp. 83-92 ◽  
Author(s):  
A. F. M. CAMARGO ◽  
E. R. FLORENTINO
Keyword(s):  
Population Dynamics ◽  
Primary Production ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Net Primary Production ◽  
Growth Period ◽  
Pistia Stratiotes ◽  
Annual Productivity ◽  
Lotic Environment ◽  
Low Levels

In this paper we evaluated the population dynamics and obtained estimates of the net primary production of the aquatic macrophyte Nymphaea rudgeana in an arm of the Itanhaém River (São Paulo State, Brazil). This species presents, in the studied area, a broad seasonal variation of biomass. As from November (13.1 g DW/m²) we observed a gradual increase of biomass that reached a maximum in February (163.1 g DW/m²). Then, the biomass decreased, maintaining low levels until a new growth period. The reduction of biomass is associated to the development of floating aquatic macrophytes (Pistia stratiotes and Salvinia molesta) and, subsequently to environmental factors (higher salinity values) that are unfavorable to their development. The net primary production of N. rudgeana was estimated from the biomass data, and the annual productivity value was estimated between 3.02 and 3.82 t/ha/year.

scholarly journals Estimation of Net Primary Production of Rice Crop using CASA model in Nankana Sahib.

2019 ◽  
Vol 01 (01) ◽  
Author(s):  
Ayesha Behzad ◽  
Usman Rafique ◽  
Mushtaq Qamar ◽  
Bilal Islam ◽  
Hafiz Umer Hameed ◽  
...  
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Growth Period ◽  
Rice Crop ◽  
Growth Stages ◽  
Casa Model ◽  
Rice Area ◽  
Reporting Service ◽  
Sunshine Hours ◽  
Wet Biomass

Estimation of Net Primary Production (NPP) is crucial for the supply of food/wood. Precise estimates of NPP are important for sustainable development. We used Light Use Efficiency (LUE) model to appraise various growth-related processes e.g., photosynthesis, respiration and transpiration, in the rice plant. The study site received 1213 actual sunshine hours in comparison to total possible sunshine hours which were 1595 during the complete Rice Growth Period (RGP). Water stress was estimated throughout the RGP which resulted in surplus of water in early growth stages (W=53) and deficiency in the final ripening stage with W=0.14. Careful results indicate that about 5128 kg/ha of wet biomass was generated during the complete RGP. We applied a harvest index of 0.50 to estimate the dry biomass that was 2564 kg/ha which is about (2.82 ton/ha). These estimates seem to be in exaggeration according to real time field estimates collected by Crop Reporting Service (CRS) department which were (1.83 ton/ha). To manage this exaggeration, we applied the Soil Suitability Constant (ħα) which resulted as 1.99 ton/ha in suitable zone, 1.21 ton/ha in less suitable, 1.76 ton/ha in moderately suitable and 0.73 ton/ha in not suitable zones. The average yield was estimated as 1.62 ton/ha. According to CRS department, the rice area in the study site was reported as 107000 ha and the net rice production was estimated as 1,73,340 tons in the study site. The LUE model is reliable to estimate NPP of rice crop which is useful for decision makers to determine the contribution of rice in Gross Domestic Product (GDP) at regional scales in term of surplus or shortfall.

scholarly journals Catastrophic shifts in the aquatic primary production revealed by a small low-flow section of tropical downstream after dredging

2015 ◽  
Vol 75 (4) ◽  
pp. 804-811
Author(s):  
H. Marotta ◽  
A. Enrich-Prast
Keyword(s):  
Primary Production ◽  
Aquatic Macrophytes ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Light Attenuation ◽  
Low Flow ◽  
Flow Section ◽  
Net Heterotrophy ◽  
The Tropics ◽  
Catastrophic Shifts

Abstract Dredging is a catastrophic disturbance that directly affects key biological processes in aquatic ecosystems, especially in those small and shallow. In the tropics, metabolic responses could still be enhanced by the high temperatures and solar incidence. Here, we assessed changes in the aquatic primary production along a small section of low-flow tropical downstream (Imboassica Stream, Brazil) after dredging. Our results suggested that these ecosystems may show catastrophic shifts between net heterotrophy and autotrophy in waters based on three short-term stages following the dredging: (I) a strongly heterotrophic net primary production -NPP- coupled to an intense respiration -R- likely supported by high resuspended organic sediments and nutrients from the bottom; (II) a strongly autotrophic NPP coupled to an intense gross primary production -GPP- favored by the high nutrient levels and low solar light attenuation from suspended solids or aquatic macrophytes; and (III) a NPP near to the equilibrium coupled to low GPP and R rates following, respectively, the shading by aquatic macrophytes and high particulate sedimentation. In conclusion, changes in aquatic primary production could be an important threshold for controlling drastic shifts in the organic matter cycling and the subsequent silting up of small tropical streams after dredging events.

Phytoremediation of Chromium and Lead Using Water Lettuce Pistia stratiotes L.)

2013 ◽  
Vol 401-403 ◽  
pp. 2071-2075 ◽  
Author(s):  
Yuan Qing Zhou ◽  
Shu Ying Li ◽  
Yun Dong Shi ◽  
Wei Lv ◽  
Tai Bo Shen ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Pollution ◽  
Aquatic Macrophytes ◽  
Bioconcentration Factor ◽  
Aquatic Macrophyte ◽  
Pistia Stratiotes ◽  
Chromium Removal ◽  
Water Lettuce ◽  
Metal Solution

Heavy metal pollution of water is of concern for human health and ecosystem. Under present investigation Pistia stratiotes L. (water lettuce) has been tested for removal of two important heavy metals chromium (Cr) and lead (Pb) from metal solution. This species was grown at four concentrations of Cr and Pb, i.e. 5.0, 10.0, 15.0 and 20.0 mg/L, respectively in single metal solution. This aquatic macrophyte has successfully removed up to 80% of Cr and 93% of Pb after 10 days. The bioconcentration factor (BCF) value ranged between 299 and 1026 for Cr and between 1672 and 1852 for Pb, respectively. The amount of BCF in Pistia stratiotes showed that removal of Pb was higher than removal of Cr. The accumulation of heavy metals was more obvious in the roots as compared to leaves. These findings contribute to the application of aquatic macrophytes to lead and chromium removal from moderately contaminated waters.

Primary production, food web structure, and fish yields in constructed and natural wetlands in the floodplain of an African river

2013 ◽  
Vol 70 (4) ◽  
pp. 543-553 ◽  
Author(s):  
Andrew T. Jackson ◽  
Alphonse Adite ◽  
Katherine A. Roach ◽  
Kirk O. Winemiller
Keyword(s):  
Primary Production ◽  
Food Web ◽  
Aquatic Macrophyte ◽  
Net Primary Production ◽  
Large Fraction ◽  
River Channel ◽  
Nutrient Concentrations ◽  
Food Web Structure ◽  
Web Structure ◽  
Floodplain Habitats

In the Ouémé River, Africa, whedo (artificial pond) aquaculture on the floodplain is an important method of fishery production. We surveyed fishes in whedos and adjacent main-channel and floodplain habitats during the receding-water period (December 2010 – January 2011) and analyzed carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of fish and primary producer tissue samples to investigate food web structure. We also measured instream respiration, net primary production, algal biomass (chlorophyll a), and nutrient concentrations in the habitats. Floodplain habitats were more nutrient-rich than the river channel, and whedos were net heterotrophic (net primary production < 0). Phytomicrobenthos and C3 macrophytes accounted for a large fraction of fish biomass in whedos and the natural floodplain depression, while the river channel was mainly supported by seston and C3 macrophytes. Whedo food webs were dominated by piscivorous fishes and had fewer trophic transfers compared with the food web of the river channel. Our results suggest that control of aquatic macrophyte growth in whedos may yield greater algal production and consumer biomass, including harvestable fish stocks.

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