Upwelling-Driven Inner-Shelf Hypoxia and Its Connection to Oceanographic Changes in the Northeast Pacific J

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Upwelling-Driven Inner-Shelf Hypoxia and its Connection to Oceanographic Changes in the Northeast Pacific J. Barth1, B. Grantham2, F. Chan1, K. Nielsen3, D. Fox4, A. Huyer1, J. Lubchenco1, B. Menge1, A. Kirincich1, B. Hales1 and P. Wheeler1

1Oregon State University 2Washington State Dept. of Ecology 3Sonoma State University, CA 4Oregon Dept. of Fish and Wildlife Hypoxia off the central Oregon coast

Normal Inner-Shelf Rockfish Community

25 B A )) 22 20 Schooling rockfish Benthic rockfish

C 10 Fish Density (per (perFish Density Fish Density 100m 100m

0 0 Aug 2000 Jun 2001 Jul 2002 Aug 2002 Oct 2002 July 2002

Grantham et al. (2004) Significant Dungeness crab die-offs

A 400 300 200 100 70 50 B 44.7 NH-Line Newport

Stonewall Bank

44.5 500

Crab 44.3 SH-Line Mortality Classes

Latitude (°N) Latitude 100 0% 1-25% Heceta Bank 26-50% 44.1 51-75% HH-Line 76-100%

Florence 43.9 125 124.8 124.6 124.4 124.2 124 0 50 100 Longitude (°W) Percentage of Pots

Grantham et al. (2004) Low-oxygen shelf water

1960-69, 1972 average

July 2002

1.5 ml l-1

Grantham et al. (2004) Low-oxygen bottom water persisted for ~2 months

Confirmed Severe Hypoxia A Newport Winds 10 ) -1 0 (m s

Velocity -10

B Strawberry Hill 30 M Mooring Temperatures 15 C)

o 10 ( Temperature C Bottom Dissolved Oxygen 6 )

-1 4 D.O.

(ml l 2 0 6/9 6/19 6/29 7/9 7/19 7/29 8/8 8/18 8/28 9/7 06/09 06/19 06/29 07/09 07/19 07/29 08/08 08/18 08/28 09/07 10/07

1 2 3 4 5 6 2002

Grantham et al. (2004) Subarctic Invasion in 2002 caused extreme anomalies in T, S, nutrients, chlorophyll & oxygen

Freeland et al. (2003) Cold halocline during 2002

Freeland, Gatien, Huyer and Smith (2003) Wheeler et al. (2003) Ecosystem Response GLOBEC NEP, 9-11 August 2002 5-m chlorophyll (mg/m³)

hypoxic Grantham et al. (2004) chlorophyll SST

Is Heceta Bank special?

September 2002 Heceta Bank deflects coastal upwelling jet offshore

low-velocity inshore

Castelao and Barth (2004) Possible mechanisms for cold-water anomaly in CCS

anomalously strong: June 2002 SST (color) and wind stress anomalies • 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)

Murphree et al. (2003) See also:

• Freeland (PICES XIII: S1-1818)

• Crawford et al. (PICES XIII: S7-2160)

• Bograd et al. (PICES XIII: S9-2084) Was low-oxygen deep water present in previous years?

100

Depth (m) 28-29 May 2001 150

200 0

50 11-12 August 2001 100 Depth (m) 150

200 125 0’W 124 40’W 124 20’W Vertical sections of oxygen (ml/l) at 44 13’W B. Hales (OSU) Hypoxia and invertebrate die-offs in summer 2004

1.43 ml l-1

A. Kirincich/J. Barth (OSU) wind LB

Heceta salinity Bank oxygen SH

PISCO-OSU T/S properties of 2004 source water were not anomalous

2004 2003 14 2002 13 12 2001 11 2000 10 1999 9 1998 Temperature 8 1997 7 6 5 31 31.5 32 32.5 33 33.5 34 34.5 Salinity

PISCO-OSU 2003

LTOP

1997

PDO MEI (normalized by 1961-71 summer std dev) Summer Temperature Anomalies Huyer et al. (S9-1871) Oxygen in 2004 source water was not anomalously low

DO (ml l-1)

012345678 NH-25 0

50 1960-69, 1970 July 2002 • 1999 to 2001 LTOP mean • 2002 July LTOP 100 •2003 July LTOP •2004 July Peterson/PISCO 150

Depth (m) •2004 Aug Peterson/PISCO

200 Error bars = 95% C.I.

250 Shelf respiration signal during summer 2004

Changes in DO along the 33.61 isohaline 8/30/2004 3.5 8/3/2004 7/13/2004 6/14/2004 3 7/19/2004 8/2/2004 2.5 9/16/2004

-1 1 ml l l-1) (ml DO 2

1.5 -124.800 -124.600 -124.400 -124.200 -124.000

Sufficient near-bottom organic carbon to fuel consumption of 1 ml l-1 of DO

PISCO-OSU Upwelling-Driven Inner-Shelf Hypoxia: Summary

Deep low-oxygen water upwelled onto continental shelf (this is normal)

Shelf bottom water can become hypoxic from a combination of low-oxygen source waters and respiration

Flow-topography interaction at Heceta Bank creates low-velocity lee region with high surface chlorophyll

Location and duration of hypoxic water in inner-shelf habitats controlled by event-scale wind forcing

Low-oxygen source water in 2002 from Subarctic invasion

Relatively normal source water properties in 2004: respiration more important

Future events? • Hypothesis testing with models • Observing systems