Management of wetlands by biomanipulation studies


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Management of wetlands by biomanipulation studies

  1. 1. MANAGEMENT OF WETLANDS BY Presentation by Livi Wilson and Jitendra Kumar College of Fisheries, KVAFSU, Mangalore, Karnataka BIOMANIPULATION STUDIES
  2. 2. NEED FOR WETLAND MANAGEMENT Natural wetlands –ECOLOGICAL ENGINEERS for waste water treatment  They function as filters, sinks, transformation sites for chemicals  Natural wetlands have been severely altered by the chronic exposure to pollutants, especially nutrients. 
  3. 3. EFFECTS OF INCREASED NUTRIENT & TURBIDITY LEVELS • Decreased biomass of large-bodied zooplankton • Elevated biomass of planktivorous & benthivorous fish • Shifts from submerged macrophyte dominance to phytoplankton dominance
  4. 4. EFFECTS OF EUTROPHICATION Increase in algal biomass ,including toxic cyanobacteria  As a consequence ,colour,taste & odour due to dissolved organic carbon & cyanobacterial blooms cause major water quality problems  cause enormous treatment cost 
  5. 5. CONT….  Cyanobacterial blooms can cause serious health problems including hepatoentritis,liver damage, promotion of tumour growth,gastroenteritis,hepatitis,renal malfunctioning & haemorrhaging. Burch(1993)
  6. 6. BIOMANIPULATION Increasing grazing pressure on phytoplankton Increase water clarity & promote the growth of aquatic macrophytes Reduce grazing pressure on zooplankton
  7. 7. BIOMANIPULATION A new tool for water management (Gulati et al. 1990).  Biomanipulation is a widely accepted & frequently applied eco-technology to improve the environmental quality of standing waters  Based on the concept of cascading trophic interactions in aquatic food web  Introduced by Shapiro in 1975 
  8. 8. INCREASING POPULARITY OF BIOMANIPULATION IS DUE TO Absence of toxic chemicals High effectiveness Low cost Absence of machinery
  9. 9. BIOMANIPULATION Adjusting the biological community to achieve a desired outcome
  10. 10. DESIRED OUTCOME INCLUDES Less turbid water Removal of pest species Reduced phytoplankton blooms
  11. 11. DISCRETE MECHANISMS BEHIND BIOMANIPULATION  Macrophytes Biomanipulation can be considered in the theoritical context of two alternative stable state equilibrium ,as the extreme perturbation required to move from a phytoplankton dominated state to one dominated by macrophytes Aquatic macrophytes have been identified as a key component for the long term success of biomanipulation management
  12. 12. CONT… Macrophytes stabilize the sediment preventing resuspension of nutrients as well as utilizing nutrients for their own growth.  Algal blooms is repressed by the macrophytes which can keep the water clear for a long period during the year  Aquatic macrophytes such as Characeae can colonize large parts of the benthos  Once established Characeae is suggested to have a high resistance to the negative effects of fluctuating phytoplakton turbidity 
  13. 13. FISH In Europe most turbid water lakes are dominated by bream,roach,common carp …  While clear water are dominated by pike,eel.European catfish,redfin perch…  Redfin perch have also been identified as a potential contributor to the turbid water state as their feeding eliminates large filter feeding cladocerans allowing phytoplankton to flourish 
  14. 14. CONT… In another Matveev (1994) experiments with mosquito fish (Gambusia holbrooki) determined that the species directly stimulated the growth of the phytoplankton by excretion  Hence biomanipulation can be defined more broadly as a removal or biomass reduction of any undesirable fish, irrespective of the impact on the zooplankton grazing, then a reduction in phtoplankton biomass could be expected. 
  15. 15. BENTHIVOROUS FISH A reduction in benthivorous fish is also suggested to have a favorable impact on the biomanipulation process(Lamarra 1975)  They stir up the bottom when feeding  Enhancing turbidity  Impairing the colonization & growth of macrophytes  Complete removal of Characeae 
  16. 16. BENTHIVOROUS FISH They stir up the bottom when feeding Impairing the colonization & growth of macrophytes Complete removal of Characeae Enhancing turbidity Loss of stability A reduction in benthivorous fish -a favorable impact on the biomanipulation process(Lamarra 1975)
  17. 17. PHYTOPLANKTIVOROUS FISH  The role of phytoplanktivorous fish in biomanipulation is gaining acceptance They also improve the water quality Some fish species can actively eliminate cyanobacterial blooms by grazing directly up on them Eg :silver carp ,bighead carp 
  18. 18. CRITERIA FOR SUCCESSFUL APPLICATION Lake area <4 ha most suitable (Reynolds 1994)  Water depth < 3 m more effective in shallow Zooplankton fauna –Daphnia foremost contributor to the success of biomanipulation  They are recognized as the most significant genus to impact upon algae blooms  When large Daphnia are absent ,zooplankton cannot reduce phytoplankton biomass(McQueen 1986)  
  19. 19. REFERENCES  EUTROPHICATION- RESEARCH AND APPLICATION TO WATER SUPPLY DAVID W. SUTCLIFFE AND J. GWYNFRYN JONES Published by the Freshwater Biological Association  Lake restoration and biomanipulation in temperate lakes: relevance forsubtropical and tropical lakes By Erik Jeppesen1.2*, Martin Søndergaard1, Nestor Mazzeo3, Mariana Meerhoff Biomanipulation : a useful tool for freshwater wetland mitigation ? By David G.Angeler Edited by
  20. 20. THANK YOU 