management of wetlands by biomanipulation studies
TRANSCRIPT
jitendera
nduat@
gm
ail.co
m
MANAGEMENT OF WETLANDS BY BIOMANIPULATION STUDIES
Presentation by
Livi Wilson and Jitendra Kumar
College of Fisheries, KVAFSU, Mangalore, Karnataka
jitendera
nduat@
gm
ail.co
mNEED 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.
jitendera
nduat@
gm
ail.co
mEFFECTS OF INCREASED NUTRIENT & TURBIDITY LEVELS• Shifts from
submerged macrophyte dominance to phytoplankton dominance
• Decreased biomass of large-bodied zooplankton
• Elevated biomass of planktivorous & benthivorous fish
jitendera
nduat@
gm
ail.co
m
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
jitendera
nduat@
gm
ail.co
m
CONT….
Cyanobacterial blooms can cause serious health problems including hepatoentritis,liver damage, promotion of tumour growth,gastroenteritis,hepatitis,renal malfunctioning & haemorrhaging. Burch(1993)
jitendera
nduat@
gm
ail.co
m
BIOMANIPULATIONReduce grazing pressure on zooplankton
Increase water clarity & promote the growth of aquatic macrophytes
jitendera
nduat@
gm
ail.co
m
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
jitendera
nduat@
gm
ail.co
m
INCREASING POPULARITY OF BIOMANIPULATION IS DUE TO
Low cost
Absence of
machinery
Absence of toxic
chemicals
High effectivene
ss
jitendera
nduat@
gm
ail.co
m
BIOMANIPULATION
Adjusting the biological community to achieve a desired outcome
jitendera
nduat@
gm
ail.co
m
DESIRED OUTCOME INCLUDES
Reduced phytoplankton blooms
Less turbid water
Removal of pest species
jitendera
nduat@
gm
ail.co
m
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
jitendera
nduat@
gm
ail.co
m
CONT…
Macrophytes stabilize the sediment preventing re-suspension 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
jitendera
nduat@
gm
ail.co
m
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
jitendera
nduat@
gm
ail.co
m
CONT…
In another Matveev et.al (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.
jitendera
nduat@
gm
ail.co
m
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
jitendera
nduat@
gm
ail.co
m
BENTHIVOROUS FISH
A reduction in benthivorous fish -a favorable impact on
the biomanipulation process(Lamarra 1975)
They stir up the bottom when feeding
Impairing the colonization & growth
of macrophytes
Complete removal of Characeae
Enhancing turbidity
Loss of stability
jitendera
nduat@
gm
ail.co
m
PHYTOPLANKTIVOROUS FISH
The role of phytoplanktivorous fish in biomanipulation is gaining acceptance
Some fish species can actively eliminate cyanobacterial blooms by grazing directly up on them
Eg :silver carp ,bighead carp
They also improve the water quality
jitendera
nduat@
gm
ail.co
m
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 et.al 1986)
jitendera
nduat@
gm
ail.co
m
REFERENCES EUTROPHICATION- RESEARCH AND APPLICATION TO WATER
SUPPLY
Edited by
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
jitendera
nduat@
gm
ail.co
m
THANK YOU