Climate change in the shallows – interacting effects of diel-cycling hypoxia and acidification* Denise Breitburg Andrew Keppel Seth Miller Rebecca Burrell
*unpublished student data removed from presentation
Atmospheric CO2
Acidification Respiration
+CO2
Hypoxia/ deoxygenation
-O2 Eutrophication
Fisheries
warming
Multiple stressors – management, understanding
Atmospheric CO2
Acidification Respiration
+CO2
Hypoxia/ deoxygenation
-O2
warming
Multiple stressors – management, understanding
Breitburg et al., in press; data from Maas et al. 2014, Breitburg et al., unpublished
Costa Rica Dome 0-1000 m
Estuarine salt marsh 1 m
Chesapeake Bay
Gedan et al, unpubl
Breitburg et al., 2015
Shallow Chesapeake Bay high productivity restricted circulation nutrient enriched
high respiration seasonal & diel-cycling hypoxia
Diel-cycling hypoxia and acidification • Patterns? • Do diel-cycling acidification and hypoxia affect
native species in spite of potential adaptation and daily periods of recovery? (Experiments with oysters & fish)
Contrasting patterns at 3 sites in Chesapeake Bay ’
dis
so
lve
d o
xyg
en
(m
g/L
)
0
2
4
6
8
10
12
time of day
pH
6.5
7.0
7.5
8.0
8.5
Oxygen and pH daily cycles
MD-DNR: eyesonthebay.net
‘Classic’ diel cycling’
Bear Creek
‘Classic’ diel cycling’ d
iss
olv
ed
ox
yg
en
(m
g/L
)
0
2
4
6
8
10
12
time of day
pH
6.5
7.0
7.5
8.0
8.5
Oxygen and pH daily cycles
Daylight – Photosynthesis dominates + oxygen, -CO2
‘Classic’ diel cycling’ d
iss
olv
ed
ox
yg
en
(m
g/L
)
0
2
4
6
8
10
12
time of day
pH
6.5
7.0
7.5
8.0
8.5
Oxygen and pH daily cycles
Dark – Respiration dominates - oxygen, +CO2
R² = 0.76
6.5
6.7
6.9
7.1
7.3
7.5
7.7
7.9
8.1
8.3
0 2 4 6 8 10 12
pH
DO (mg/L)
Salt marsh Creek Rhode River, Chesapeake Bay
Strong tidal signal
0
2
4
6 D
O (
mg
/L) P ≤ 0.0002
6.4
6.6
6.8
7
7.2
7.4
L F H E
pH
Tide Stage
P ≤ 0.0005
Low Flood High Ebb
0
1
2
3
4
5
6
7
8
9
10
0:00 2:24 4:48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 0:00
DO
(m
g/L
)
Time of day
DO Time Series (7/16-21 GCRW Marsh)
7/16/2014
7/17/2014
7/18/2014
7/19/2014
7/20/2014
7/21/2014
High Tide
Low Tide
High Tide
Low Tide
Dawn - 5:54-5:58
daw
n
Tide-dominated pattern: timing of minima vary among days
R² = 0.9365
6.5
7
7.5
8
8.5
9
0 2 4 6 8 10 12
pH
DO (mg/L)
DO vs. pH (7/10-8/11 SERC Dock) Dock site Rhode River, Chesapeake Bay
Mid-day minima
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
0:00 2:24 4:48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 0:00
DO
(m
g/L
)
Time of Day
DO Time Series (8/6-11 SERC Dock)
8/8/2014
8/9/2014
8/10/2014
Dawn 6:10-6:16
High Tide Low Tide Low Tide High Tide
Stratification on sunny days – Mid-day minima
DO and pH at 2 m continue to decline after dawn
0.00
0.50
1.00
1.50
2.00
2.50
2.00 3.00 4.00 5.00 6.00
De
pth
(m
)
DO (mg/L) 7.00 7.10 7.20 7.30 7.40
pH
5:32
5:56
6:18
6:43
7:06
7:25
7:50
8:13
Sample Time
Shallow water cycles of dissolved oxygen and pH
Large spatial variation in timing and magnitude of cycles- different drivers dominate patterns Spatial variation in ways hypoxia and acidification interact with diel patterns of behavior and physiology
Disease Growth
Eastern Oyster (Crassostrea virginica)
Growth Sensitivity to hypoxia
Atlantic & inland silversides (Menidia menidia & M. beryllina)
LabVIEW program
manifold
Rep
. 1
R
ep.
2
Rep
. 3
R
ep.
4
Rep
. 5
R
ep.
6
N2 MFC
00.00 N2 system,
n=3
CO2 system, n=4
O2 system, n=3
20psi
LiqN2 with gas removal
V
V
O2 MFC
00.00
20psi
O
2
CO2 MFC
00.00
15psi
CO2
Emergency fail closed solenoid
Air system, n=5
Air compres
sor
Condensing coil in freezer
Drip leg to drain
condensate
CO2 stripper column (soda
lime filled)
drying column (indicating silica
filled) Particle filter
00.00
drain
CO2 free air
^ ^
Normally open
When energized
3-way solenoid
air
H2
O
Air MFC
15psi
V
Emergency air
compressor
Emergency fail open solenoid
Oxyguard DO probes
Durafet pH probes
Trt.
1
Tr
t.
2
Trt.
3
Tr
t.
4
Trt.
5
Sp
ar e
air
H2
O
Burrell et al., accepted pending revision
LabView program
0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5
10.010.511.0
Dis
solv
ed o
xyge
n (
mg/
L)
2012 dissolved oxygen trend
DO_WB_mean
DO_WP_mean
DO_GP_mean
DO_BP_mean
DO_BB_mean
6.90
7.00
7.10
7.20
7.30
7.40
7.50
7.60
7.70
7.80
7.90
8.00
7/3
1/2
012
2:2
4
7/3
1/2
012
14
:24
8/1
/20
12 2
:24
8/1
/20
12 1
4:2
4
8/2
/20
12 2
:24
8/2
/20
12 1
4:2
4
8/3
/20
12 2
:24
8/3
/20
12 1
4:2
4
8/4
/20
12 2
:24
8/4
/20
12 1
4:2
4
pH
(u
nit
s)
2012 pH trend
DO_WB_mean
DO_WP_mean
DO_GP_mean
DO_BP_mean
DO_BB_mean
Eastern Oyster (Crassostrea virginica)
Immune response/disease (Dermo – Perkinsus marinus) hemolymph pH hemocyte function prevalence and intensity of infections Juvenile growth
Mea
n pH
±SE
7.0
7.2
7.4
7.6
7.8
8.0
Time
0 2 4 6 8 10
Mea
n pH
±SE
7.0
7.2
7.4
7.6
7.8
8.0
Time
0 2 4 6 8 10
Control
Cycling pH
Cycling DO & pH
Cycling DO;
Hemolymph pH affected by water pH
water
hemolymph
Virginia Clark - 2014
Prop
ortio
n ph
agoc
ytic
hem
ocyt
es
0.00
0.05
0.10
0.15
0.20
Severe cycling hypoxia - Normcapnia Severe cycling hypoxia - Cycling pH Normoxia - Normcapnia Normoxia - Cycling pH
Cycling (DO, CO2, DO+CO2) stimulates hemocyte function
low oxygen high oxygen hi pH low pH hi pH low pH
(cycling down to DO = 0.5, pH = 7.1)
Keppel et al., in review
Infe
ctio
n In
tens
ity
(mea
n of
all
dise
ased
oys
ters
)
0.8
1.0
1.2
1.4
1.6
1.8
Severe cycling hypoxia - Normcapnia Severe cycling hypoxia - Cycling pH Moderate cycling hypoxia - Cycling pH Normoxia - Normcapnia Normoxia - Cycling pH
Stimulation of hemocytes only tends to reduce infection progression when oxygen is high
low oxygen high oxygen hi pH low pH hi pH low pH Keppel et al., in review
Low salinity year ΩCalcite =0.69
High salinity year ΩCalcite =1.87
Juvenile growth cycling down to
DO = 0.5, pH = 7.1
Keppel 2014
The effect of diel-cycling pH differed in high and low salinity/ ΩCalcite years
0
1
2
3
4
5
6
6.87.0
7.27.4
7.67.8
8.0
02
46810
Cle
aran
ce R
ate
(L h
r-1 g
-1)
pH
Dissolved Oxygen (mg L -1) at Low Plateau
p < 0.0001Adj R2 = 0.27
Low pH slightly increases oyster filtration rates
2 way ANOVA then Planar regression Clark 2014.
Atlantic and inland Silversides- Growth, Aquatic Surface Respiration & Mortality
Seth Miller
Growth of juvenile Menidia beryllina was lower relative to controls when fish were reared in diel-cycling dissolved oxygen or constant hypoxia conditions, but was not affected by cycling pH or constant low pH
© Dave Conover
Laboratory experiments indicated that simultaneous exposure to low pH can make fish more sensitive to low dissolved oxygen
Even brief daily exposures to acidification and hypoxia can negatively affect species that are native to systems with large natural fluctuations
So – Why worry about multiple stressors?
For mobile species, co-occurrence with other stressors can determine exposure to acidification
Almost all species tested behaviorally avoid low dissolved oxygen. Co-occurring hypoxia may therefore reduce exposure to respiration-driven acidification
Individual stressors can either exacerbate or reduce effects of other stressors
We can’t predict consequences or manage effectively if we don’t consider the full context in which organisms live