Cyanobacteria, microcystins and cylindrospermopsin in public drinking supply reservoirs of Brazil
Nutrient use by cyanobacteria in subtropical reservoirs
Transcript of Nutrient use by cyanobacteria in subtropical reservoirs
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Nutrient use by cyanobacteria in subtropical reservoirs
Michele Burford
Tim Davis, Priya Muhid, Matt Prentice Australian Rivers Institute
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Stratified lakes & reservoirs promote cyanobacteria
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Key questions
Should we invest in controlling nutrient inputs?
How do we decide whether nutrient inputs
are a problem? Nutrient concentrations Nutrient ratios Algal measures – chl, algal #, toxins
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PN PN
PN
PN
PN PN
PN PN PN
PN 10 days supply
PN PN
1 day supply
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Algal bioassays
N, P and N+P additions Photosynthetic yield
response (PHYTOPAM) after 24-48 h
Typically co-limited in
summer
Muhid & Burford, in press Inland Waters
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Mesocosm experiments
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Experimental design
Treatments Control Nitrate Urea Phosphate Nitrate + phosphate Urea + phosphate
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Background nutrients
mg/L DIN + urea DIP DN:DIP
Expt 1 0.032 0.004 19:1 Expt 2 0.019 0.004 12:1
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Biovolum
e (x10
7 µm
3 mL-‐1)
Biovolum
e (x10
7 µm
3 mL-‐1)
Ambient Control Nitrate Urea PhosphateNitrate + P Urea + P
Cyanobacteria Diatoms Chlorophytes CryptophytesChrysophytes Dinoflagellates Euglenophytes
Ambient Control Nitrate Urea Phosphate Nitrate + P Urea + P
Experiment 1 Experiment 2
3
2
1
0
3
2
1
0
T. Davis, unpubl. data
Urea + P stimulated phytoplankton
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C. raciborskii response
0.0E+00
4.0E+06
8.0E+06
1.2E+07
1.6E+07
0.0E+00
4.0E+06
8.0E+06
1.2E+07
1.6E+07
AmbientT0
Ambient
Contro
l
Nitrate
Urea
Phosp
hate
Nitrate+
P
Urea+P
AmbientT0
Ambient
Control
Nitrate
Urea
Phosp
hate
Nitrate+
P
Urea+P
Cel
l bio
vol.
(€m
3 ml-1
) *
Expt 1
Expt 2
Expt 3
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Cylindrospermopsins cell quota
0.00E+00
2.00E-07
4.00E-07
6.00E-07
8.00E-07
AmbientT
0
Ambient
Contro
l
Nitrate
Urea
Phosp
hate
Nitrate+
P
Urea+P
QTCYN
QdeoxyCYNQCYN A
A
A + B
A + B
BB B
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Source: Google Earth
1
2
3
4
Upper reservoir zone
Mid reservoir zone
Lower reservoir zone
Source: Badin Gibbes
33P-phosphate uptake studies
Lake Wivenhoe, Queensland
Monthly sampling Four sites
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Rapid P uptake
M. Prentice, unpubl. data
Threshold value
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Uptake by starved C.raciborskii
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 5 10 15 20 25 30
Specific DIP up
take rate
[µg DIP µg Chl a
L-‐1hr
-‐1]
Days post T=0
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P P
Active uptake
organicP
Slow use
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Conclusions
Nitrogen and phosphorus promotes algal growth
Cyanobacteria have an active uptake mode
Measuring nutrient conc is of limited value
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Acknowledgements Students & staff
– A.Chuang, S.Faggotter, C. Laurikaunen, C.Polson Collaborators
– Seqwater (P.Orr) – B.Neilan, J.Beardall, K.O’Brien, D. Hamilton Funding sources
Seqwater, Aust. Research Council, Griffith University
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Species which grew
Expt 1 Expt 2 Expt 3
Monoraphidium Achnanthidium Synedra C. raciborskii Planktolyngbya
Achnanthidium Aulecoseira Synedra C. raciborskii Peridinium Cryptomonas
Aulecoseira C. raciborskii Planktolyngbya
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Reservoirs in subtropical Australia
Tropic of Capricorn
Burford et al. 2012 Aquat Sci Burford et al. 2012 Aquat Sci
0.002
0.006
0.01
0.014
0.018
0
0.02
0.04
0.06
0.08
0.1
0.12
0.002
0.0025
0.003
0.0035
0.004
Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09
Ammonium
Nitrate + nitrite
Phosphate
Con
c (m
g L-1
)
Burford et al 2012
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N+P increased chlorophyll a
0
20
40
60
80
0
20
40
60
80
Ambient
Contro
l
Contro
l
Nitrate
Urea
Phosp
hate
Nitrate+P
Urea+P
Chl
a (¬ g
L-1
)Expt 1
Expt 2
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Background nutrients
mg/L DIN + urea DIP DIN:DIP Post floods 0.138 0.004 76:1 Expt 3 0.044 0.006 16:1
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Post inflow event Biovolum
e (x10
7 µm
3 mL-‐1)
Ambient Control Nitrate Urea Phosphate Nitrate + P Urea + P
Cyanobacteria Diatoms Chlorophytes CryptophytesChrysophytes Dinoflagellates Euglenophytes
1.6
1.2
0.8
0.4
0
Experiment 3
Euphotic depth half previous experiments