DECLINING DISSOLVED OXYGEN LEVELS OFF
OF CENTRAL CALIFORNIA
A LIC E R EN
AU G U ST 12, 2015
MBA R I IN TER N
U N IV ER SITY O F MA IN E
THE WORKPLACE
DECLINING OXYGEN IN
THE WORLD’S OCEANS
Atmospheric
Exchange
(Ventilation)
Respiration
Photosynthesis
WHAT’S GOING ON IN CENTRAL CALIFORNIA?
Data Source Time Period Frequency
Data Quality Data Type
BOG
(Chavez)
1998-2015
Seasonal
Good
Cast verified
with bottle
titration
CalCOFI
1950-2015
Scattered
OK
Bottle
ARGO
2001-2015
Daily, hourly
Needs QC
Float sensor
SWFSC
Rockfish
Survey
2008-2011
Annual
OK
Cast
ROVCTD
1987-2015
Many per
year
Needs QC
ROV sensor
ROMSCoSiNE
Model
1991-2010
3-day
Needs QC
Model
LINE 67 (CalCOFI and BOG)
Station
67-50
67-55
67-60
67-65
67-70
67-75
67-80
67-85
67-90
Distance
to Shore
23
64
96
131
170
208
240
280
316
BOG : LINE67
AVERAGE Oxygen with Depth
0
Depth (m)
-100
-200
-300
-400
-500
300
Hypoxic Boundary:
60 µmol/kg
200
100
Distance to Shore (km)
50
BOG : LINE67
AVERAGE Winter Oxygen with Depth
0
Depth (m)
-100
-200
-300
-400
-500
300
Hypoxic Boundary:
60 µmol/kg
200
100
Distance to Shore (km)
0
BOG : LINE67
AVERAGE Spring Oxygen with Depth
0
Depth (m)
-100
-200
-300
-400
-500
300
Hypoxic Boundary:
60 µmol/kg
200
100
Distance to Shore (km)
0
BOG : LINE67
AVERAGE Summer Oxygen with Depth
0
Depth (m)
-100
-200
-300
-400
-500
300
Hypoxic Boundary:
60 µmol/kg
200
100
Distance to Shore (km)
0
BOG : LINE67
AVERAGE Autumn Oxygen with Depth
0
Depth (m)
-100
-200
-300
-400
-500
300
Hypoxic Boundary:
60 µmol/kg
200
100
Distance to Shore (km)
0
Depth (m)
BOG : LINE67
AVERAGE Oxygen with Depth
Hypoxic Boundary:
60 µmol/kg
Distance to Shore (km)
Depth (m)
BOG : LINE67
AVERAGE Winter Oxygen with Depth
Hypoxic Boundary:
60 µmol/kg
Distance to Shore (km)
Depth (m)
BOG : LINE67
AVERAGE Spring Oxygen with Depth
Hypoxic Boundary:
60 µmol/kg
Distance to Shore (km)
Depth (m)
BOG : LINE67
AVERAGE Summer Oxygen with Depth
Hypoxic Boundary:
60 µmol/kg
Distance to Shore (km)
Depth (m)
BOG : LINE67
AVERAGE Autumn Oxygen with Depth
Hypoxic Boundary:
60 µmol/kg
Distance to Shore (km)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
Depth (m)
Dissolved Oxygen (µmol/kg)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Distance to Shore (km)
Time (yr)
OXYGEN TEMPORAL VARIABILITY ALONG
DENSITY SURFACES
Density Range
Oxygen Characteristics
25.5 – 26.2
Short-term Variability (4-8 years)
26.3 – 26.5
Little Change
26.6 – 26.8
Long-term Decline
26.9 – 27.5
Little Change & Possible Increase
Density (kg/m^3)
SPATIAL PERSPECTIVE OF DECLINE
Distance to Shore (km)
Dissolved Oxygen (µmol/kg)
SIGNIFICANT DECLINES
IN DISSOLVED OXYGEN
Time (yr)
Station
Distance
Density
67-80
240 km
26.7
Slope
(µmol/kg-yr)
R^2
P-value
-2.40
0.43
1.5e-11
Dissolved Oxygen (µmol/kg)
SIGNIFICANT DECLINES
IN DISSOLVED OXYGEN
Time (yr)
Station
Distance
Density
67-75
210 km
26.7
Slope
(µmol/kg-yr)
R^2
P-value
-2.40
0.49
4.4e-12
Dissolved Oxygen (µmol/kg)
SIGNIFICANT DECLINES
IN DISSOLVED OXYGEN
Time (yr)
Station
Distance
Density
67-65
130 km
26.7
Slope
(µmol/kg-yr)
R^2
P-value
-2.19
0.40
2.1e-10
CONCLUSIONS
Researcher
Density
Decline
(µmol/kg-yr)
Time Period
Region
Bograd et al.
2015
26.5
-1 to -2
1984-2012
S. California Bight
Pierce et al.
2012
26.3 – 26.5
-0.3 to -0.9
1960s-2000s
Newport, Oregon
Line
Mecking et al.
2008
26.6
-0.5 to -1.1
1994-2004
152 ºW
Whitney et al.
2007
26.3 – 27.0
-0.4 to -0.7
1950s-2006
Ocean Station
Papa (50 ºN, 145 ºW)
BOG data
(Chavez)
26.7
-2.4
1998-2013
Line 67
CONCLUSIONS
•
Clear decline in dissolved oxygen at depth offshore of
Monterey Bay
•
Strongest signal at 350-400 m, 26.6-26.8 sigma-theta
•
Strongest decline observed compared to literature values:
2.4 µmol/kg-yr
•
Pattern of dissolved oxygen declines along entire California
Current
ONGOING WORK
Why?
What are the mechanisms for the decreasing
dissolved oxygen levels?
ACKNOWLEDGEMENTS
•
Dave Anderson
•
Fred Bahr
•
Jen Patterson
•
Aric Bickel
•
Mike McCann
•
•
Francisco Chavez
•
Reiko Michisaki
•
Monique Messie
Rich Schramm
•
Marguerite Blum
•
Rachel Carson Crew
•
Tom O’Reilly
•
Peter Brewer Lab
•
Lisa “Z” Ziccarelli
•
Patrick Whaling
•
•
Fei Chai
George Matsumoto, Linda
Kuhnz, and Interns
•
Huijie Xue
QUESTIONS?