SlideShare uma empresa Scribd logo
1 de 19
Baixar para ler offline
A seminar on 
Nitrogen cycle in aquatic ecosystem 
Submitted by, 
B.F.Sc. 1st yr 2nd sem 
FS-06/13
Introduction: 
 Nitrogen is essential for many processes and is 
crucial for any life on Earth. 
It is a component in all amino acids, as 
incorporated into proteins, and is present in the 
bases that make up nucleic acids, such as DNA 
and RNA. 
 The process of converting nitrogen into 
compounds that can be used by plants and 
animals is called the nitrogen cycle. 
 Although Earth’s atmosphere is an abundant 
source of nitrogen, most is relatively unusable 
by plants. 
 This trans- formation can be carried out through 
both biological and physical processes.
Cycling of Nitrogen in Aquatic Ecosystem : 
 Four processes participate in the 
cycling of nitrogen through the 
biosphere as well as aquatic 
ecosystem : 
1) Nitrogen fixation 
2) Decay 
3) Nitrification 
4) Denitrification 
Microorganisms play major roles 
in these processes
Fixation 
 Nitrogen fixation refers to the 
conversion of N2 to either NO3 
or NH4(Organic N)by bacteria. 
 Terrestrial systems: Soil 
bacteria in root nodules of 
legumes. 
 Aquatic systems: Blue green 
algae( Anabaena, Nostoc, 
Azolla) 
 Biological, meteorological, 
industrial transformations 
also occur.
Decay 
 The proteins made by plants enter and pass through food 
webs just as carbohydrates do. At each trophic level, their 
metabolism produces organic nitrogen compounds that 
return to the environment, chiefly in excretions. 
 The final beneficiaries of these materials are 
microorganisms of decay. 
 They breakdown the molecules in excretions and dead 
organisms into ammonia (NH3).
Contd….. 
 NH3 separated from organic protein via microbial 
activity. 
 This process referred to as deaminification or 
ammonification. 
 NH3 is released to water column (mineralization) 
and assimilated into primary productivity (NH+ H+ 
3 --> NH+). 
4 
 Ammonification is heterotrophic, under aerobic or 
anaerobic conditions.
Nitrification 
 The term nitrification 
refers to the conversion of 
ammonium to nitrate 
(pathway 3-4 opposite). 
 Responsible: nitrifying 
bacteria known as 
chemoautotrophs. 
 These bacteria gain their 
energy by oxidizing NH3, 
while using CO2 as a source 
of carbon to synthesize 
organic compounds.
Contd….. 
 First step by Nitrosomonas sp. 
 second step by Nitrobacter sp. 
 Both steps/reactions use NH4 
+ and NO2 
- as an energy 
source, CO2 as a carbon source. 
This is a non-photosynthetic type of growth. NH3 
and NH4 
+ are both either assimilated by aquatic 
plants for growth or nitrified (oxidized) to NO3 
- 
(nitrate). 
Nitrate can also be used as a growth substrate.
 Two step process: 
NH4 
+ + 1.5O2 
 NO2 
- + 2H+ + H2O 
NO2 
- + 0.5O2 
 NO3 
- 
 These are oxygen-driven reactions. Reaction runs best at 
pH 7-8 and 25-30oC. 
 However, under low DO, it runs in reverse. 
 It occurs in the hypolimnion under eutrophic (stagnant) 
conditions.
Denitrification 
 By this process, NO3 in soil 
or water is converted into 
atmospheric N2, nitric 
oxide or nitrous oxide. 
 This must occur under 
anaerobic conditions 
(anaerobic respiration). 
 Presence of O2 can reverse 
the reaction. 
 It is again, mediated by 
bacteria (Pseudomonas sp., 
Alkaligenes sp. and Bacillus 
sp.)
Nitrogen: aqueous forms 
 Gaseous form of nitrogen (N2) is most prevalent. 
 Gaseous followed by: nitrite, nitrate, ammonia or 
ammonium. 
 Ratio of NH3:NH4 
+ rises with pH. 
 Unfertilized ponds: TAN (NH3 +NH4 
+) = 0.05-0.075 
mg/L. 
 Fertilized ponds: TAN = 0.5 mg/L, 0.075 mg NO3 
-
Nitrogen Amendments 
 Nitrogen added as fertilizer to 
ponds: urea 
 Immediately upon addition, it 
starts to decline. 
 Only small portion detectable 
from metabolic processes. 
 Plants typically take it up, die, 
mud deposit. 
 Inorganic nitrogen typically 
denitrified in the hypolimnion. 
 High afternoon pH = increased 
volatization. 
urea
Affects of Nitrogen Cycle In Aquatic Ecosystem : 
 Ammonia Toxicity : 
 Both NH3 and NH4 
+ are toxic to fish/invertebrates. 
 In Blood/tissue of fishes if NH3 increases then blood pH also 
increases. 
 It causes imbalance in enzyme activity, reduced membrane 
stability. 
 Increases O2 consumption by tissues, gill damage, reduced O2 
transport. 
 Reduced growth of fishes, histological changes in gills/other 
organs. 
 Toxicity tolerance varies due to biological variability of 
different strains of species, Eggs are most tolerant (fish), 
Larvae least tolerant, olders are more tolerant. 
 NH3 is more toxic when DO levels are low.
 Nitrate Toxicity : 
 Nitrite reacts with hemoglobin to form methemoglobin. 
 In this process, iron converted from ferrous (Fe2+) to ferric 
(Fe3+) form. 
Ferric form of iron cannot bind with oxygen,so blood 
changes from red to brown. 
 Those fish having methemoglobin reductase enzyme can 
convert iron moeity back to ferrous. 
 Recovery from nitrite toxicity usually occurs when fish are 
transferred to better water.Complete recovery can occur in 
24 h. 
 Nitrite is quickly transported across gill membrane by 
lamellar chloride cells.So cells can’t distinguish between 
NO- and Cl- 
2
Nitrogen cycle in aquatic ecosystem...................................
Nitrogen cycle in aquatic ecosystem...................................
Conclusion: 
 Nitrogen Cycle play an important role as bio-geochemical 
cycle.It carries on the balance of aquatic ecosystem. 
 Though free nitrogen is not present in aquatic 
environment,but it present in aquatic ecosystem in a 
combined form as NH+. 
4 
 Chemical processing, or natural fixation are necessary to 
convert gaseous nitrogen into compound forms by living 
organisms, which makes nitrogen a crucial component of 
food production. 
 The nitrogen cycle is the process by which nitrogen is 
converted between its various chemical forms.
Reference: 
WEBSITES : 
 www.google.com 
 www.wikipedia.com 
 www.ask.com 
BOOKS : 
 “Fundamental of Aquatic Ecology” : Wiley,2nd 
Edition. 
 “Freshwater Ecology”(2nd Edition) – Walter 
K.Dodds and Matt R.Whiles. 
 “Introduction to Limnology”- Prof. S.Welch
Nitrogen cycle in aquatic ecosystem...................................

Mais conteúdo relacionado

Mais procurados

Phosphorous Cycle in Marine environment
Phosphorous Cycle in Marine environmentPhosphorous Cycle in Marine environment
Phosphorous Cycle in Marine environmentKashyap Kumar
 
Claasification of zooplankton and Benthos
Claasification of zooplankton and BenthosClaasification of zooplankton and Benthos
Claasification of zooplankton and BenthosKANTHARAJAN GANESAN
 
zonations of sea and ecological classification of marine biota
 zonations of sea and ecological classification of marine biota  zonations of sea and ecological classification of marine biota
zonations of sea and ecological classification of marine biota Mariyam Nazeer Agha
 
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEM
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEM
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEMpatel sahebb
 
INTRODUCTION OF PLANKTON
INTRODUCTION OF PLANKTONINTRODUCTION OF PLANKTON
INTRODUCTION OF PLANKTONMahiRaj10
 
STRATIFICATION OF MARINE ECOSYSTEM
STRATIFICATION OF MARINE ECOSYSTEMSTRATIFICATION OF MARINE ECOSYSTEM
STRATIFICATION OF MARINE ECOSYSTEMpatel sahebb
 
Marine Ecosystems
Marine EcosystemsMarine Ecosystems
Marine Ecosystemspg8s
 
Freshwater Ecosystems
Freshwater EcosystemsFreshwater Ecosystems
Freshwater EcosystemsEdelyn Cagas
 
Primary productivity estimation
Primary productivity estimationPrimary productivity estimation
Primary productivity estimationAthira Pk
 
Freshwater ecology
Freshwater ecology Freshwater ecology
Freshwater ecology Terry Baita
 
Adaptations in deep sea fishes
Adaptations in deep sea fishesAdaptations in deep sea fishes
Adaptations in deep sea fishesAnuSharma263
 

Mais procurados (20)

Phosphorous Cycle in Marine environment
Phosphorous Cycle in Marine environmentPhosphorous Cycle in Marine environment
Phosphorous Cycle in Marine environment
 
Claasification of zooplankton and Benthos
Claasification of zooplankton and BenthosClaasification of zooplankton and Benthos
Claasification of zooplankton and Benthos
 
zonations of sea and ecological classification of marine biota
 zonations of sea and ecological classification of marine biota  zonations of sea and ecological classification of marine biota
zonations of sea and ecological classification of marine biota
 
Lake ecology 2017
Lake ecology 2017Lake ecology 2017
Lake ecology 2017
 
Classification of lakes
Classification of lakes Classification of lakes
Classification of lakes
 
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEM
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEM
STRATIFICATION OF FRESHWATER ECOSYSTEMSTRATIFICATION OF FRESHWATER ECOSYSTEM
 
INTRODUCTION OF PLANKTON
INTRODUCTION OF PLANKTONINTRODUCTION OF PLANKTON
INTRODUCTION OF PLANKTON
 
STRATIFICATION OF MARINE ECOSYSTEM
STRATIFICATION OF MARINE ECOSYSTEMSTRATIFICATION OF MARINE ECOSYSTEM
STRATIFICATION OF MARINE ECOSYSTEM
 
Marine Ecosystems
Marine EcosystemsMarine Ecosystems
Marine Ecosystems
 
Marine ecosystems
Marine  ecosystemsMarine  ecosystems
Marine ecosystems
 
Deep sea adaptations
Deep sea adaptationsDeep sea adaptations
Deep sea adaptations
 
Seawater and its properties
Seawater and its propertiesSeawater and its properties
Seawater and its properties
 
Zonation in the ocean powerpoint
Zonation in the ocean powerpointZonation in the ocean powerpoint
Zonation in the ocean powerpoint
 
Fresh water ecosystem
Fresh water ecosystemFresh water ecosystem
Fresh water ecosystem
 
Freshwater Ecosystems
Freshwater EcosystemsFreshwater Ecosystems
Freshwater Ecosystems
 
Physical and chemical characteristics of limnetic environment
Physical and chemical characteristics of limnetic environmentPhysical and chemical characteristics of limnetic environment
Physical and chemical characteristics of limnetic environment
 
Plankton
PlanktonPlankton
Plankton
 
Primary productivity estimation
Primary productivity estimationPrimary productivity estimation
Primary productivity estimation
 
Freshwater ecology
Freshwater ecology Freshwater ecology
Freshwater ecology
 
Adaptations in deep sea fishes
Adaptations in deep sea fishesAdaptations in deep sea fishes
Adaptations in deep sea fishes
 

Semelhante a Nitrogen cycle in aquatic ecosystem...................................

Nitrogen cycle and NITROGEN FIXATION
Nitrogen cycle and NITROGEN FIXATIONNitrogen cycle and NITROGEN FIXATION
Nitrogen cycle and NITROGEN FIXATIONAnjali Tripathi
 
Nutrient Cycle.pptx
Nutrient Cycle.pptxNutrient Cycle.pptx
Nutrient Cycle.pptxSayabDawar
 
Presentation on biogeochemical cycles 2
Presentation on biogeochemical cycles 2Presentation on biogeochemical cycles 2
Presentation on biogeochemical cycles 2naimal kainat
 
biogeochemical_cycle.pdf
biogeochemical_cycle.pdfbiogeochemical_cycle.pdf
biogeochemical_cycle.pdfMidhatSarfraz
 
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfv
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfvN2 CYCLE PRESENTATION. 11.05.22.pptx gkfv
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfvAniket789077
 
Unit III- Nitrogen metabolism and Growth
Unit III- Nitrogen metabolism and GrowthUnit III- Nitrogen metabolism and Growth
Unit III- Nitrogen metabolism and GrowthTUSHAR WANKHEDE
 
Biogeochemical cycle
Biogeochemical cycleBiogeochemical cycle
Biogeochemical cycleRashmi Yadav
 
Biogeochemical cycle
Biogeochemical cycleBiogeochemical cycle
Biogeochemical cycleRashmi Yadav
 
Nitrogen cycle (1) 1
Nitrogen cycle (1) 1Nitrogen cycle (1) 1
Nitrogen cycle (1) 1AJEV2000
 
nitrogenmetabolism-201028181632.pdf
nitrogenmetabolism-201028181632.pdfnitrogenmetabolism-201028181632.pdf
nitrogenmetabolism-201028181632.pdfStarletMG
 
Nitrogen Fixation
Nitrogen FixationNitrogen Fixation
Nitrogen Fixationdpdhanera
 
Nitrogen cycle
Nitrogen cycleNitrogen cycle
Nitrogen cycleAjmal Aju
 
Roles of microbes in nitrogen cycle aritriya
Roles of microbes in nitrogen cycle aritriyaRoles of microbes in nitrogen cycle aritriya
Roles of microbes in nitrogen cycle aritriyaaritriyajana
 
Ecology ecosystem
Ecology ecosystemEcology ecosystem
Ecology ecosystemKumar
 

Semelhante a Nitrogen cycle in aquatic ecosystem................................... (20)

Nitrogen cycle and NITROGEN FIXATION
Nitrogen cycle and NITROGEN FIXATIONNitrogen cycle and NITROGEN FIXATION
Nitrogen cycle and NITROGEN FIXATION
 
Nutrient Cycle.pptx
Nutrient Cycle.pptxNutrient Cycle.pptx
Nutrient Cycle.pptx
 
Nitrogen Cycle
Nitrogen CycleNitrogen Cycle
Nitrogen Cycle
 
Nitrogen cycle
Nitrogen cycleNitrogen cycle
Nitrogen cycle
 
Presentation on biogeochemical cycles 2
Presentation on biogeochemical cycles 2Presentation on biogeochemical cycles 2
Presentation on biogeochemical cycles 2
 
biogeochemical_cycle.pdf
biogeochemical_cycle.pdfbiogeochemical_cycle.pdf
biogeochemical_cycle.pdf
 
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfv
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfvN2 CYCLE PRESENTATION. 11.05.22.pptx gkfv
N2 CYCLE PRESENTATION. 11.05.22.pptx gkfv
 
Unit III- Nitrogen metabolism and Growth
Unit III- Nitrogen metabolism and GrowthUnit III- Nitrogen metabolism and Growth
Unit III- Nitrogen metabolism and Growth
 
Nitrogen cycle
Nitrogen cycleNitrogen cycle
Nitrogen cycle
 
Biogeochemical cycle
Biogeochemical cycleBiogeochemical cycle
Biogeochemical cycle
 
Biogeochemical cycle
Biogeochemical cycleBiogeochemical cycle
Biogeochemical cycle
 
Nitrogen cycle (1) 1
Nitrogen cycle (1) 1Nitrogen cycle (1) 1
Nitrogen cycle (1) 1
 
Nitrogen metabolism
Nitrogen metabolismNitrogen metabolism
Nitrogen metabolism
 
nitrogenmetabolism-201028181632.pdf
nitrogenmetabolism-201028181632.pdfnitrogenmetabolism-201028181632.pdf
nitrogenmetabolism-201028181632.pdf
 
Nitrogen Fixation
Nitrogen FixationNitrogen Fixation
Nitrogen Fixation
 
Nutrient cycles
Nutrient cyclesNutrient cycles
Nutrient cycles
 
Nitrogen cycle
Nitrogen cycleNitrogen cycle
Nitrogen cycle
 
nutrients cycle
nutrients cyclenutrients cycle
nutrients cycle
 
Roles of microbes in nitrogen cycle aritriya
Roles of microbes in nitrogen cycle aritriyaRoles of microbes in nitrogen cycle aritriya
Roles of microbes in nitrogen cycle aritriya
 
Ecology ecosystem
Ecology ecosystemEcology ecosystem
Ecology ecosystem
 

Mais de WBUAFS

Food additives
Food additivesFood additives
Food additivesWBUAFS
 
Hazard Analysis Critical Control Point
Hazard Analysis Critical Control PointHazard Analysis Critical Control Point
Hazard Analysis Critical Control PointWBUAFS
 
FISH MEAL
FISH MEALFISH MEAL
FISH MEALWBUAFS
 
ISO 9000:2000
ISO 9000:2000ISO 9000:2000
ISO 9000:2000WBUAFS
 
Auxiliary marine machinery systems
Auxiliary marine machinery systemsAuxiliary marine machinery systems
Auxiliary marine machinery systemsWBUAFS
 
Sous vide technology
Sous vide technologySous vide technology
Sous vide technologyWBUAFS
 
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...WBUAFS
 
Fatty acid composition of fish liver and body oils
Fatty  acid  composition  of  fish  liver  and  body oilsFatty  acid  composition  of  fish  liver  and  body oils
Fatty acid composition of fish liver and body oilsWBUAFS
 
Cell culture
Cell cultureCell culture
Cell cultureWBUAFS
 
Infusoria culture
Infusoria cultureInfusoria culture
Infusoria cultureWBUAFS
 
Nutritional requirements of exotic carps in different life stages
Nutritional requirements of exotic carps in different life stagesNutritional requirements of exotic carps in different life stages
Nutritional requirements of exotic carps in different life stagesWBUAFS
 
Microeconomics
MicroeconomicsMicroeconomics
MicroeconomicsWBUAFS
 
Coral reefs
Coral reefsCoral reefs
Coral reefsWBUAFS
 
Inland fishery resources of world
Inland fishery  resources of worldInland fishery  resources of world
Inland fishery resources of worldWBUAFS
 

Mais de WBUAFS (14)

Food additives
Food additivesFood additives
Food additives
 
Hazard Analysis Critical Control Point
Hazard Analysis Critical Control PointHazard Analysis Critical Control Point
Hazard Analysis Critical Control Point
 
FISH MEAL
FISH MEALFISH MEAL
FISH MEAL
 
ISO 9000:2000
ISO 9000:2000ISO 9000:2000
ISO 9000:2000
 
Auxiliary marine machinery systems
Auxiliary marine machinery systemsAuxiliary marine machinery systems
Auxiliary marine machinery systems
 
Sous vide technology
Sous vide technologySous vide technology
Sous vide technology
 
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...
Chemical treatment prior to freezing: antioxidants, cryoprotectants and other...
 
Fatty acid composition of fish liver and body oils
Fatty  acid  composition  of  fish  liver  and  body oilsFatty  acid  composition  of  fish  liver  and  body oils
Fatty acid composition of fish liver and body oils
 
Cell culture
Cell cultureCell culture
Cell culture
 
Infusoria culture
Infusoria cultureInfusoria culture
Infusoria culture
 
Nutritional requirements of exotic carps in different life stages
Nutritional requirements of exotic carps in different life stagesNutritional requirements of exotic carps in different life stages
Nutritional requirements of exotic carps in different life stages
 
Microeconomics
MicroeconomicsMicroeconomics
Microeconomics
 
Coral reefs
Coral reefsCoral reefs
Coral reefs
 
Inland fishery resources of world
Inland fishery  resources of worldInland fishery  resources of world
Inland fishery resources of world
 

Nitrogen cycle in aquatic ecosystem...................................

  • 1. A seminar on Nitrogen cycle in aquatic ecosystem Submitted by, B.F.Sc. 1st yr 2nd sem FS-06/13
  • 2. Introduction:  Nitrogen is essential for many processes and is crucial for any life on Earth. It is a component in all amino acids, as incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA.  The process of converting nitrogen into compounds that can be used by plants and animals is called the nitrogen cycle.  Although Earth’s atmosphere is an abundant source of nitrogen, most is relatively unusable by plants.  This trans- formation can be carried out through both biological and physical processes.
  • 3. Cycling of Nitrogen in Aquatic Ecosystem :  Four processes participate in the cycling of nitrogen through the biosphere as well as aquatic ecosystem : 1) Nitrogen fixation 2) Decay 3) Nitrification 4) Denitrification Microorganisms play major roles in these processes
  • 4. Fixation  Nitrogen fixation refers to the conversion of N2 to either NO3 or NH4(Organic N)by bacteria.  Terrestrial systems: Soil bacteria in root nodules of legumes.  Aquatic systems: Blue green algae( Anabaena, Nostoc, Azolla)  Biological, meteorological, industrial transformations also occur.
  • 5. Decay  The proteins made by plants enter and pass through food webs just as carbohydrates do. At each trophic level, their metabolism produces organic nitrogen compounds that return to the environment, chiefly in excretions.  The final beneficiaries of these materials are microorganisms of decay.  They breakdown the molecules in excretions and dead organisms into ammonia (NH3).
  • 6. Contd…..  NH3 separated from organic protein via microbial activity.  This process referred to as deaminification or ammonification.  NH3 is released to water column (mineralization) and assimilated into primary productivity (NH+ H+ 3 --> NH+). 4  Ammonification is heterotrophic, under aerobic or anaerobic conditions.
  • 7. Nitrification  The term nitrification refers to the conversion of ammonium to nitrate (pathway 3-4 opposite).  Responsible: nitrifying bacteria known as chemoautotrophs.  These bacteria gain their energy by oxidizing NH3, while using CO2 as a source of carbon to synthesize organic compounds.
  • 8. Contd…..  First step by Nitrosomonas sp.  second step by Nitrobacter sp.  Both steps/reactions use NH4 + and NO2 - as an energy source, CO2 as a carbon source. This is a non-photosynthetic type of growth. NH3 and NH4 + are both either assimilated by aquatic plants for growth or nitrified (oxidized) to NO3 - (nitrate). Nitrate can also be used as a growth substrate.
  • 9.  Two step process: NH4 + + 1.5O2  NO2 - + 2H+ + H2O NO2 - + 0.5O2  NO3 -  These are oxygen-driven reactions. Reaction runs best at pH 7-8 and 25-30oC.  However, under low DO, it runs in reverse.  It occurs in the hypolimnion under eutrophic (stagnant) conditions.
  • 10. Denitrification  By this process, NO3 in soil or water is converted into atmospheric N2, nitric oxide or nitrous oxide.  This must occur under anaerobic conditions (anaerobic respiration).  Presence of O2 can reverse the reaction.  It is again, mediated by bacteria (Pseudomonas sp., Alkaligenes sp. and Bacillus sp.)
  • 11. Nitrogen: aqueous forms  Gaseous form of nitrogen (N2) is most prevalent.  Gaseous followed by: nitrite, nitrate, ammonia or ammonium.  Ratio of NH3:NH4 + rises with pH.  Unfertilized ponds: TAN (NH3 +NH4 +) = 0.05-0.075 mg/L.  Fertilized ponds: TAN = 0.5 mg/L, 0.075 mg NO3 -
  • 12. Nitrogen Amendments  Nitrogen added as fertilizer to ponds: urea  Immediately upon addition, it starts to decline.  Only small portion detectable from metabolic processes.  Plants typically take it up, die, mud deposit.  Inorganic nitrogen typically denitrified in the hypolimnion.  High afternoon pH = increased volatization. urea
  • 13. Affects of Nitrogen Cycle In Aquatic Ecosystem :  Ammonia Toxicity :  Both NH3 and NH4 + are toxic to fish/invertebrates.  In Blood/tissue of fishes if NH3 increases then blood pH also increases.  It causes imbalance in enzyme activity, reduced membrane stability.  Increases O2 consumption by tissues, gill damage, reduced O2 transport.  Reduced growth of fishes, histological changes in gills/other organs.  Toxicity tolerance varies due to biological variability of different strains of species, Eggs are most tolerant (fish), Larvae least tolerant, olders are more tolerant.  NH3 is more toxic when DO levels are low.
  • 14.  Nitrate Toxicity :  Nitrite reacts with hemoglobin to form methemoglobin.  In this process, iron converted from ferrous (Fe2+) to ferric (Fe3+) form. Ferric form of iron cannot bind with oxygen,so blood changes from red to brown.  Those fish having methemoglobin reductase enzyme can convert iron moeity back to ferrous.  Recovery from nitrite toxicity usually occurs when fish are transferred to better water.Complete recovery can occur in 24 h.  Nitrite is quickly transported across gill membrane by lamellar chloride cells.So cells can’t distinguish between NO- and Cl- 2
  • 17. Conclusion:  Nitrogen Cycle play an important role as bio-geochemical cycle.It carries on the balance of aquatic ecosystem.  Though free nitrogen is not present in aquatic environment,but it present in aquatic ecosystem in a combined form as NH+. 4  Chemical processing, or natural fixation are necessary to convert gaseous nitrogen into compound forms by living organisms, which makes nitrogen a crucial component of food production.  The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms.
  • 18. Reference: WEBSITES :  www.google.com  www.wikipedia.com  www.ask.com BOOKS :  “Fundamental of Aquatic Ecology” : Wiley,2nd Edition.  “Freshwater Ecology”(2nd Edition) – Walter K.Dodds and Matt R.Whiles.  “Introduction to Limnology”- Prof. S.Welch