Management of wetlands by biomanipulation studies

MANAGEMENT

OF WETLANDS BY

Presentation by
Livi Wilson and Jitendra Kumar
College of Fisheries, KVAFSU, Mangalore, Karnataka
jitenderanduat@gmail.com


BIOMANIPULATION STUDIES

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.




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

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




CONT….



Cyanobacterial blooms can cause serious health
problems including hepatoentritis,liver damage,
promotion of tumour
growth,gastroenteritis,hepatitis,renal malfunctioning
& haemorrhaging. Burch(1993)

BIOMANIPULATION

Increasing grazing
pressure on phytoplankton
Increase water clarity &
promote the growth of
aquatic macrophytes


Reduce grazing pressure
on zooplankton

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




INCREASING POPULARITY OF
BIOMANIPULATION IS DUE TO

Absence of
toxic
chemicals

High
effectiveness


Low cost

Absence of
machinery

BIOMANIPULATION

Adjusting the biological
community to achieve a
desired outcome

DESIRED OUTCOME

INCLUDES

Less turbid water

Removal of pest
species


Reduced
phytoplankton blooms

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

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



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




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.




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



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)

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


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)





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


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

Management of wetlands by biomanipulation studies

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