ocean deoxygenation and coastal hypoxia i n a changing world ”
DESCRIPTION
Ocean Deoxygenation and Coastal Hypoxia i n a Changing World ”. GESAMP 39 18 April 2012 Nancy N. Rabalais et al. Louisiana Universities Marine Consortium [email protected] http://www.gulfhypoxia.net. Goolsby et al. 1999, Rabalais 2002. Point Source 10%. Nonpoint Source 90%. - PowerPoint PPT PresentationTRANSCRIPT
Ocean Deoxygenation and Coastal Hypoxiain a Changing World”
GESAMP 3918 April 2012
Nancy N. Rabalais et al.Louisiana Universities Marine Consortium
[email protected]://www.gulfhypoxia.net
Goolsby et al. 1999, Rabalais 2002
Point Source10%
Nonpoint Source
90%
http://water.usgs.gov/nawqa/sparrow/gulf_findings/Alexander et al. 2008 &
Nutrient Yields from the Mississippi Basin
Effects are more far reachingthan 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
• up to 22,000 km2
• 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
TX MSLA
April 29 rain
June 18 rain
2011
2010maximum
average
minimum
Mississippi River Discharge HydrographsTarbert Landing, MS (1930-2011)
Cubi
c fe
et p
er se
cond
x 1
000
*
Trans C&FShelfwide
* Heterosigma bloom
Station: C6C, approx 15 miles south of LUMCON (29o 52.12 N / 90 o 29.42 W)Date: March 21, 2011Bottom Depth: 19.5 mBloom Color: Greenish-brownSalinity: 28.7 psuChlorophyll: 117 ug/LOxygen: 204% oxygen saturationDO: 16-17 mg/L
Heterosigma akashiwo
Predicting Hypoxia in summer(nitrate-N flux in May, year)
Turner et al. 2006
LA LATX MS ALMississippi RiverAtchafalaya 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
June 18, 2011 rain
Anthropogenic activities
Vertical carbon flux
Nutrient-enhancedproductivity
Physical environment(Stratification +)
(Oxygen saturation -)(Current shifts)
(Tropical storms)
Nutrient loads (+) (-)
Hydrologiccycle (+) (-)
Water temperature
(mostly +)
Bottom-waterhypoxia
Climate variabilityclimate change
Sedimentary carbonand nutrient pools
Sea levelrise (+)
Harmful & noxious
algal blooms
WindsReactive N(mostly +)
Biological responses(Metabolic rates
mostly +)(Primary production +)
(Respiration +)
Rabalais et al. 2009, 2010
(modified by N. Rabalais; Galloway and Cowling 2002; Boesch 2002)
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
1800 1850 1900 1950 2000 2050
0
20
40
60
80
100
120
Humans, millions Fertilizer, Tg NLegumes/Rice, Tg N NOx emissions, Tg N
Symptoms of Eutrophication
Developing Countries
DevelopedCountries
They are increasing
The FutureClimate Change
BiofuelsIncreased Population
Increased AgribusinessIncreased Atmospheric
Deposition