Upwelling-Driven Inner-Shelf Hypoxia and its Connection to Oceanographic Changes in the
Northeast PacificJ. Barth1, B. Grantham2, F. Chan1, K. Nielsen3, D. Fox4,
A. Huyer1, J. Lubchenco1, B. Menge1, A. Kirincich1, B. Hales1 and P. Wheeler1
1Oregon State University2Washington State Dept. of Ecology3Sonoma State University, CA4Oregon Dept. of Fish and Wildlife
0
5
10
15
20
25
Aug 2000 Jun 2001 Jul 2002 Aug 2002 Oct 2002
Schooling rockfishBenthic rockfish
Fish
Den
sity
(per
100
m2 )
00
5
10
15
20
25
0
5
10
15
20
25
Aug 2000 Jun 2001 Jul 2002 Aug 2002 Oct 2002
Schooling rockfishBenthic rockfish
Fish
Den
sity
(per
100
m2 )
0
AB
C
Grantham et al. (2004)
Hypoxia off the central Oregon coast
July 2002
Normal Inner-ShelfRockfish Community
125 124.8 124.6 124.4 124.243.9
44.1
44.3
44.5
44.7
Longitude (°W)
Latit
ude
(°N
)
50
Heceta Bank
Stonewall Bank
HH-Line
NH-Line
0% 1-25% 26-50% 51-75%76-100%
SH-Line
70100200300400
Newport
100
500
B
Florence
A
124
Crab Mortality Classes
Percentage of Pots0 50 100
Grantham et al. (2004)
Significant Dungeness crab die-offs
1.5 ml l-1
Low-oxygen shelf water
Grantham et al. (2004)
1960-69, 1972 average
July 2002
-10
0
10
06/09 06/19 06/29 07/09 07/29 08/08 08/18 08/28 09/07
10
15Strawberry Hill 30 M Mooring Temperatures
Confirmed Severe Hypoxia
10/07
1 2 3 4 5 6
07/19
Newport Winds
Velo
city
(m s
-1)
Tem
pera
ture
(o C)
A
B
0
2
4
6
6/ 9 6/ 19 6/ 29 7/ 9 7/ 19 7/ 29 8/ 8 8/ 18 8/ 28 9/ 7
D.O
.(m
l l-1
)
Bottom Dissolved OxygenC
Grantham et al. (2004)
2002
Low-oxygen bottom water persisted for ~2 months
Freeland et al.(2003)
Subarctic Invasion in 2002caused extreme anomalies in T, S, nutrients, chlorophyll & oxygen
Cold halocline during 2002
Freeland, Gatien, Huyer and Smith (2003)Freeland, Gatien, Huyer and Smith (2003) Wheeler et al. (2003)
GLOBEC NEP, 9-11 August 20025-m chlorophyll (mg/m³)
hypoxic
Ecosystem Response
Grantham et al. (2004)
chlorophyll SST
September 2002
Is Heceta Bankspecial?
Castelao and Barth (2004)
Heceta Bank deflects coastal upwelling jet offshore
low-velocity inshore
Murphree et al. (2003)
anomalously strong:
• southward transport of Subarctic waters into the North Pacific Current (NPC)
• eastward flow in the eastern part of the NPC
• equatorward flow in the CCS
Freeland et al. (2003)
See also:
• Freeland (PICES XIII: S1-1818)
• Crawford et al. (PICES XIII: S7-2160)
• Bograd et al. (PICES XIII: S9-2084)
June 2002 SST (color)and wind stress anomalies
Possible mechanisms for cold-water anomaly in CCS
28-29 May 2001
11-12 August 2001
0
100
200
150
50D
epth
(m)
125 0’W 124 40’W 124 20’W
0
100
200
150
50
Dep
th (m
)
Vertical sections of oxygen (ml/l) at 44 13’W B. Hales (OSU)
Was low-oxygen deep water present in previous years?
© Jane Lubchenco/PISCO©Elizabeth Gates
Hypoxia and invertebratedie-offs in
summer 2004
A. Kirincich/J. Barth (OSU)
Cross-shelf section sampledwith a towed, undulating
Vehicle (Acrobat)
1.43 ml l-1
PISCO-OSU
LB
SH
HecetaBanksalinity
oxygen
wind
5
6
7
8
9
10
11
12
13
14
31 31.5 32 32.5 33 33.5 34 34.5Salinity
Tem
pera
ture
2004
2003
2002
2001
2000
1999
1998
1997
T/S properties of 2004 source water were not anomalous
PISCO-OSU
MEI
PDO
2003 1997 LTOP
Summer Temperature Anomalies(normalized by 1961-71 summer std dev)
Huyer et al. (S9-1871)
NH-25
1960-69, 1970
• 1999 to 2001 LTOP mean
• 2002 July LTOP
•2003 July LTOP
•2004 July Peterson/PISCO
•2004 Aug Peterson/PISCO
Error bars = 95% C.I.
DO (ml l-1)
0 1 2 3 4 5 6 7 8
Dep
th (m
)0
50
100
150
200
250
Oxygen in 2004 source water was not anomalously low
July 2002
Changes in DO along the 33.61 isohaline
1.5
2
2.5
3
3.5
-124.800 -124.600 -124.400 -124.200 -124.000
DO
(ml l-1)
8/30/20048/3/20047/13/20046/14/20047/19/20048/2/20049/16/2004
Shelf respiration signal during summer 2004
PISCO-OSU
Sufficient near-bottom organic carbon to fuel consumptionof 1 ml l-1 of DO
1 ml l-1
Upwelling-Driven Inner-Shelf Hypoxia: Summary
Deep low-oxygen water upwelled onto continental shelf(this is normal)
Shelf bottom water can become hypoxic from acombination of low-oxygen source waters and respiration
Flow-topography interaction at Heceta Bank createslow-velocity lee region with high surface chlorophyll
Location and duration of hypoxic water in inner-shelfhabitats controlled by event-scale wind forcing
Low-oxygen source water in 2002 from Subarctic invasion
Relatively normal source water properties in 2004: respirationmore important
Future events?• Hypothesis testing with models• Observing systems
