kam w. tang amy r. shields walker o. smith, jr. virginia institute of marine science
DESCRIPTION
ESCAP Ecology of Solitary and Colonial Antarctic Phaeocystis. David Elliott Maureen Lynch Jennifer Gaydos Britt Anderson Eva Bailey Heidi Geisz Adriana Veloza Emily Yam. Dark and cold survival of Phaeocystis antarctica. - PowerPoint PPT PresentationTRANSCRIPT
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Kam W. Tang Kam W. Tang Amy R. Shields Amy R. Shields Walker O. Smith, Jr. Walker O. Smith, Jr.
Virginia Institute of Marine ScienceVirginia Institute of Marine ScienceGloucester Point, Virginia, USAGloucester Point, Virginia, USA
Dark and cold survival ofDark and cold survival ofPhaeocystis antarcticaPhaeocystis antarctica
David Elliott Maureen Lynch Jennifer GaydosDavid Elliott Maureen Lynch Jennifer GaydosBritt Anderson Eva Bailey Heidi GeiszBritt Anderson Eva Bailey Heidi GeiszAdriana Veloza Emily YamAdriana Veloza Emily Yam
ESCAPESCAPEcology of Solitary and Colonial Antarctic Ecology of Solitary and Colonial Antarctic PhaeocystisPhaeocystis
Acknowledgements:Acknowledgements:U.S. NSF ANT-0440478U.S. NSF ANT-0440478RPSC, McMurdo Station, Crary LabRPSC, McMurdo Station, Crary Lab
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Rousseau et al. (1994)
P. globosaP. globosaP. pouchetiiP. pouchetiiP. antarcticaP. antarctica
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ESCAP – Ecology of Solitary and Colonial Antarctic ESCAP – Ecology of Solitary and Colonial Antarctic PhaeocystisPhaeocystis
- Survival of grazing- Survival of grazing
- Survival of freezing and darkness in winter- Survival of freezing and darkness in winter
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Chlorophyll-size-fraction-specific grazing by microzooplankton in McMurdo Sound as determined by dilution technique (Preliminary results)
Grazing coefficient (d-1) Date 0.7 m fraction 5 m fraction 20 m fraction
01-03-06 NS 0.14 NS
01-09-06 0.05 NS NS
01-16-06 NS NS NS
01-24-06 0.14 0.24 0.12 01-30-06 NS NS NS
02-06-06 0.17 0.10 NS
Chlorophyll-size-fraction-specific grazing by microzooplankton in McMurdo Sound as determined by dilution technique
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Zo
op
lan
kto
n D
MS
P (
nm
ol in
d-1 )
0
5
10
15
20
25McMurdo Sound 2005-2006 Long Island Sound
Limac
ina
Clione
Calanu
s acu
tus
Oithon
a
Micr
ocala
nus
Calano
ides
Parae
ucha
eta
Copep
od n
aupli
i
Steph
os
Polych
aete
larv
ae
Cteno
phor
e
P. antarctica single cells and small colonies are consumed by (small) grazers, which subsequently support the higher trophic levels.
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P. antarctica
Grazers + Food
Dialysis bag
Does grazing affect colony formation?(sensu Jakobsen & Tang 2002)
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Grazing Signal experiment S-1numbers represent geometric mean
underlined numbers indicate significant difference betweengrazing treatment and control; Rank-sum Test; p<0.05
Day
0 5 10 15
Co
lon
y d
iam
eter
( m
)
0
200
400
600
Day
0 5 10 15
Co
lon
y d
iam
eter
( m
)
0
200
400
600
105.8 111.8
93.1
105.8 44.446.4
Grazing
Control
137.0
68.8
Consistent with previous studies on P. globosa (Jakobsen & Tang 2002; Tang 2003)
Grazer
No grazer
P. antarctica exposed to “grazing signal” had significantly larger colonies
* * *
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Can P. antarctica survive austral winter?
• Physiological response to long period of darkness.
• Physiological response to freeze-thaw treatment.
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Light treatmentLight treatment
Dark treatmentDark treatment
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Dark-treatment
0 5 10 15 20
0.7
m fr
actio
n ch
loro
phyl
l
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 5 10 15 20
5 m
frac
tion
chlo
roph
yll
0.2
0.3
0.4
0.5
0.6
0.7
Day
0 5 10 15 20
20
m fr
actio
n ch
loro
phyl
l
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
p< 0.001
p< 0.05
>0.7 m “Single cells + Colonies”
>5 m “Small+ Large colonies”
>20 m “Large colonies”
Ch
loro
phy
ll (
g l-1
)Significant decrease
Significant increase
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Day
0 5 10 15 20
Sin
gle
ce
lls m
l-1 (
me
an
±sd
)
0
500
1000
1500
2000
2500
3000
Col 1 vs Col 4
Day
0 5 10 15 20
Co
lon
ies
ml-1 (
me
an
±sd
)
0
20
40
60
80
100
Day
0 5 10 15 20
Colo
ny d
iam
ete
r (m
m)
0.00
0.02
0.04
0.06
0.08
0.10
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Pbmax in culture: 0.19 - 4.10 (Schoemann et al. 2005)
Irradiance (mol photons m-2 s-1)
0 100 200 300 400 500
Pb
(m
gC
mg
Ch
la-1
h-1
) fo
r >
0.7
m
siz
e f
ract
ion
0.0
0.1
0.2
0.3
0.4
0.5
LightDark
Pbmax = 0.4 mgC mgChla-1 h-1
Pbmax = 0.26 mgC mgChla-1 h-1
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Freeze for 15 daysFreeze for 15 days
Recovery for up to 21 daysRecovery for up to 21 days
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Freeze-Thaw experiment FT-1(freeze-15-day)
Day
-15 0 7 14 21
Co
lon
y d
iam
ete
r (
m)
0
50
100
150
200
250
300
116.8
85.8
110.9
60.2 70.3
Freeze-Thaw experiment FT-1(freeze-15-day)
Day
-15 0 7 14 21
Cel
ls o
r co
loni
es m
l-1
10
100
1000
10000Single cellsColonies
Day
-15 0 7 14 21
Chl
orop
hyll
(g
l-1)
0
5
10
15
20
25
>0.7 m >20 m
Freeze-Thaw experiment FT-1(freeze-15-day)
Day
-15 0 7 14 21
Cel
ls o
r co
loni
es m
l-1
10
100
1000
10000Single cellsColonies
Day
-15 0 7 14 21
Chl
orop
hyll
(g
l-1)
0
5
10
15
20
25
>0.7 m >20 m
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Freeze-Thaw expt FT-1freeze-15-day
Day
-15 0 7 14 21
Fv/F
m (
me
an
+s
d)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Irradiance
0 200 400 600 800 1000 1200
ET
R
0
10
20
30
40
50 Before freezingDay 0 recoveryDay 7 recoveryDay 14 recoveryDay 21 recovery
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Grazing signal led to larger colonies --- potential defense mechanism against small grazers
P. antarctica may survive long darkness and freezing in ice during austral winter, and subsequently seed the water column population in the spring.