Ocean Deoxygenation and Coastal Hypoxia in a Changing World
GESAMP 39 18 April 2012 Nancy N. Rabalais et al. Louisiana
Universities Marine Consortium [email protected]
http://www.gulfhypoxia.net
Slide 2
Goolsby et al. 1999, Rabalais 2002 Point Source 10% Nonpoint
Source 90%
Slide 3
http://water.usgs.gov/nawqa/sparrow/gulf_findings/Alexander et
al. 2008 & Nutrient Yields from the Mississippi Basin
Slide 4
Effects are more far reaching than suspended sediment plume,
esp. N & somewhat P New Orleans dominant wind direction
Mississippi River Atchafalaya River Hypoxic Area Mississippi River
Gulf of Mexico Ecosystem Continuum Source: N. Rabalais
Slide 5
up to 22,000 km 2 4 - 5 m nearshore to 35 - 45 m offshore 0.5
km nearshore to 100 + km offshore widespread and severe in Jun Sep
Source: N. Rabalais, LUMCON Extensive, Severe Low Oxygen
Waters
Slide 6
April 29 rain June 18 rain
Slide 7
2011 2010 maximum average minimum Mississippi River Discharge
Hydrographs Tarbert Landing, MS (1930-2011) Cubic feet per second x
1000 * Trans C&F Shelfwide * Heterosigma bloom
Slide 8
Slide 9
Station:C6C, approx 15 miles south of LUMCON (29 o 52.12 N / 90
o 29.42 W) Date: March 21, 2011 Bottom Depth: 19.5 m Bloom Color:
Greenish-brown Salinity: 28.7 psu Chlorophyll: 117 ug/L Oxygen:
204% oxygen saturation DO: 16-17 mg/L Heterosigma akashiwo
Slide 10
Predicting Hypoxia in summer (nitrate-N flux in May, year)
Turner et al. 2006
Slide 11
LA TXMSAL Mississippi River Atchafalaya River Distribution of
bottom-water dissolved oxygen July 18-21 (east of the Mississippi
River delta) and July 24-30 (west of the Mississippi River delta),
2011. Data source: NN Rabalais, Louisiana Universities Marine
Consortium, and RE Turner, Louisiana State University. Funding
source: National Oceanic and Atmospheric Administration, Center for
Sponsored Coastal Ocean Research. http://www.gulfhypoxia.net
