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Remote sensing application for Remote sensing application for monitoring and assessment of monitoring and assessment of

eutrophicationeutrophicationin the NOWPAP regionin the NOWPAP region

JojiJoji IshizakaIshizaka(Nagasaki University)(Nagasaki University)

OutlineOutline

•• Definition and Consequence of Definition and Consequence of EutrophicationEutrophication

•• Toyama BayToyama Bay•• South Sea of Korea Red TideSouth Sea of Korea Red Tide•• East China Sea and Yellow SeaEast China Sea and Yellow Sea•• AriakeAriake Bay Red TideBay Red Tide

Definition of EutrophicationDefinition of Eutrophication

•• Accumulation of nutrients and organic Accumulation of nutrients and organic matter to lake and coastal environments matter to lake and coastal environments and resulted changes of ecosystem.and resulted changes of ecosystem.

•• Natural: Long term succession.Natural: Long term succession.

•• Anthropogenic (HumanAnthropogenic (Human--made): Discharge made): Discharge of waist, fertilizer etc. of waist, fertilizer etc.

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Consequence of EutrophicationConsequence of Eutrophication

•• Increase of Red Tide (HAB: harmful algal Increase of Red Tide (HAB: harmful algal bloom)bloom)

•• Decrease of Low Dissolved Oxygen Decrease of Low Dissolved Oxygen ConditionCondition

•• Mass Mortality to OrganismsMass Mortality to Organisms

BottomBottom--up Control up Control ((vs. Topvs. Top--down Control)down Control)

Fish YieldFish Yield

⇑⇑Ecosystem Structure (Ecosystem Structure (trophictrophic level)level)

⇑⇑Primary ProductionPrimary Production

⇑⇑Environments Environments (Nutrients)(Nutrients)

Food Food ChainChain

Lalli and Parsons

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Global CHLGlobal CHL--aaMost of the ocean is Most of the ocean is oligotrophicoligotrophic!!

Paradox of EutrophicationParadox of Eutrophication

•• Phytoplankton: Primary ProducerPhytoplankton: Primary ProducerOligotrophicOligotrophic Environment Environment –– Low ProductivityLow Productivity

•• Large Area is Large Area is OligotrophicOligotrophicFishing Ground Fishing Ground –– Upwelling Area (Natural Upwelling Area (Natural

Eutrophication)Eutrophication)

Appropriate Amount of Nutrient is Appropriate Amount of Nutrient is Necessary!Necessary!

What is Appropriate Amount?What is Appropriate Amount?

BeforeBefore EutrophicationEutrophication

OrganicMaterials

NutrientsFishingHarvest

OrganicMaterials

Nutrients Phytoplankton

Zooplankton Fish/Clam

NutrientsOrganic

Materials

Sedimentation

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After Artificial EutrophicationAfter Artificial Eutrophication

OrganicMaterials

FishingHarvest

Nutrients Phytoplankton

Zooplankton

Fish/Clam

NutrientsOrganic

Materials

Sedimentation

Human Pollution

OxygenDepletion

Red Tide

Blue Tide

How we can use remote sensing to How we can use remote sensing to monitoring of eutrophication.monitoring of eutrophication.

•• Direct observation of changeDirect observation of change•• Check of appropriate location of ship Check of appropriate location of ship

observationobservation•• Check of background level Check of background level

•• -- chlorophyllchlorophyll--a, red tidea, red tide•• -- SST, altimeter,,SST, altimeter,,

Toyama Bay ProjectToyama Bay ProjectMonitoring in situ Survey of Toyama BayMonitoring in situ Survey of Toyama Bay–– Observed Variable with VesselObserved Variable with Vessel

Temperature, Salinity, Water Color,Temperature, Salinity, Water Color,Transparency, Remote Sensing ReflectanceTransparency, Remote Sensing Reflectance

–– Analyzed Variable in LabAnalyzed Variable in LabDissolved Oxygen, CODDissolved Oxygen, CODPhosphate, Nitrogen and SilicatePhosphate, Nitrogen and SilicateChlChl--a, Suspended Solid, CDOM, a, Suspended Solid, CDOM,

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Analysis of MODIS Analysis of MODIS ChlChl--a Daily Imagesa Daily Images

Anti-clockwise flow pattern

Monthly Monthly SeaWiFSSeaWiFS ChlChl--a a Data Data AanalysisAanalysis (98(98--03)03)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

1998

1999

2000

2001

2002No valide dataavailable

2003

Two peaks of Chl-a concentration one in early spring and the other in fall every year

Chl-a concentration of inner are of the Bay become higher every summer

Seasonal Variability Seasonal Variability of Satellite of Satellite Chlorophyll a Chlorophyll a

1997~20021997~2002

Chlorophyll a Chlorophyll a ＞＞ 0.8 0.8 μμg lg l--11

(Yamada et al.)

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Seasonal variability of Seasonal variability of SeaWiFSSeaWiFS Chl.aChl.a from each from each sampling pointssampling points

Outer

Inner

Middle

InterInter--annual Variation annual Variation of Coastal of Coastal SeaWiFSSeaWiFSChlChl--a Concentration a Concentration

(98(98--03)03)

1998 1999 2000 2001 2002 2003

Validation of Validation of SeaWiFSSeaWiFS DataData

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Strong positive correlation(R = 0.87, N =86)

Less variability was found in spring and summer.

Comparison of in situ Comparison of in situ ChlChl--a and a and COD (Chemical Oxygen Demand)COD (Chemical Oxygen Demand)

Transport ofC. Polykrikoides

Red Tide？(MODIS, JAXA)

3. Results and Discussions

(a)

(b)

(c)

(d)

(e)

Aug. 19, 2002 Sep. 8 , 2002 True Color from MODIS bands (645, 555,469 nm).

MODIS Chlorophyll Con.

1. 10 sub-samples collected from various water condition based on true color and chlorophyll images

(NFRDI, 2004)(Son, Y.B. et al., In prep.)

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3. Results and Discussions : Spectral characteristic of sub-samples

Bright color (B1, B2) : Radiance peaks at green band.High radiance and particulate backscattering but phytoplankton absorption is minimal

High chlorophyll and red tide (H, R) : Radiance peaks at green band High absorption of the phytoplankton and gelbstoff/detritus .

Particulate backscattering values are ~3-4 times lower than in bright color samples.Low and moderate chlorophyll (L, M) : Radiance peaks from 412 nm to 531 nm (blue to green bands)

absorption and backscattering of the phytoplankton, gelbstoff, and detritus in all visual wavelengths

3. Results and Discussions : Scheme for identifying the water types

667 nm >678 nm

Turbid Water Mixed Water

Highest peak at 412 nm

Red Tide

Clear Water

Intermediate Water

No values at748 and 869 nm

Yes No

Yes

Yes

Yes

Step 1Step 3

Step 4-2

Step 4-3

Step 2-1

Step 2-2

Max(531 & 551 nm)

Radiance ratio of 412/443 is greater than that of 531/551

Step 4-1

Highest peak at 551 nm

Radiance ratio of 412/488 is greater than that of 531/551

Step 2

No

No

No

Step 4

Yes

Yes

Yes

No

No

No

Step 1: The maximum peaks in blue-to-green wavelengths to separate largely two different water types.Step 2: Determining intermediate and clear waters.

step 2-1 used the highest peak at nLw(412). Step 2-2 used that the values of nLw(748) and nLw(869) are zero.

Step 3: Turbid and mixed waters included red tide water. Turbid water used nLw(667) > nLw(678) and mixed water as nLw(667) < nLw(678).

3. Results and Discussions : Identify the water types

LC CW IW TW MW LC CW IW TW MW

19% 81%

72%

9%3%

16%

44%56%

1%

43%33%

23%

Aug. 19, 2002 Sep. 8, 2002

Step 1 Step 1

Step 2

Step 2

Step 2

Step 2

Step 3:nLw(667)>nLw(678)

Step 3:nLw(667)<nLw(678)

Step 3:nLw(667)>nLw(678)

Step 3:nLw(667)<nLw(678)

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3. Results and Discussions : HABs DetectionSep. 8, 2002Aug. 19, 2002

Step 4-1 : nLw(551) is highest peak among The 9 visible bands of MODIS

Step 4-2 :

Step 4-3 :

(NFRDI, 2004)(NFRDI, 2004)

Increase Increase of China of China Coastal Coastal Area in Area in the East the East China China SeaSea

（（Zhu, Zhu, 20032003））

Jan Feb Mar Apr

AugMay June July

Sep Oct Nov Dec

10-year average Chl-a

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Jan Feb Mar Apr

May June July Aug

Sep Oct Nov Dec

10-year average nLw555 (Sediment)

High High chl.achl.a area and area and Low Salinity WaterLow Salinity Water

(Kim et al., Submitted)

Distribution of month of maximumDistribution of month of maximum

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Distribution of month of maximumDistribution of month of maximum

浙江

省

長江

JFMAMJJASOND02468

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Seasonal Changes in Each AreaSeasonal Changes in Each Area

JFMAMJJASOND02468

10

JFMAMJJASOND02468

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10

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10 Area 4

JFMAMJJASOND02468

10 Area 5JFMAMJJASOND

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10JFMAMJJASOND

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10

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10JFMAMJJASOND

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10 Area 9

JFMAMJJASOND02468

10

JFMAMJJASOND02468

10 Area 11

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10 Area 12

JFMAMJJASOND02468

10 Area 13

JFMAMJJASOND02468

10 Area 14

JFMAMJJASOND02468

10 Area 15JFMAMJJASOND

02468

10 Area 16

浙江

省

長江

Changjiang Diluted Water

(Yamaguchi et al., In prep.)

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JFMAMJJASOND02468

10

JFMAMJJASOND02468

10

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10

JFMAMJJASOND02468

10 Area 4

JFMAMJJASOND02468

10 Area 5JFMAMJJASOND

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10 Area 9

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10

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10 Area 11

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10 Area 12

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10 Area 13

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10 Area 14

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10 Area 15JFMAMJJASOND

02468

10 Area 16

浙江

省

長江

Changjiang Diluted Water

Interannual Variability of Chl-a and Changjiang Discharge on May-Oct.

0x100 2x104 4x104 6x104 8x10402468

1012

0x100 2x104 4x104 6x104 8x1040

0.20.40.60.8

11.2

0x100 2x104 4x104 6x104 8x1040

1

2

3

4

0x100 2x104 4x104 6x104 8x1040

1

2

3

4

0x100 2x104 4x104 6x104 8x1040

0.20.40.60.8

11.21.4

R=0.27P=0.12

R=0.43P<0.01

R=0.57P<0.01

R=0.67P<0.01

(Lag= 0)

(Lag= 0)

(Lag= 1)

(Lag= 2)

R=0.70P<0.01

(Lag= 2)

CRD (m3/s)

chl-a

(mg/

m3 )

Correlation between Chl-a and Discharge with Lag 0-2 months

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Interannual Variability in the Yellow Sea

ChangjiangDischarge

Chl.a ○

nLw555

Spring Summer

Increase of Frequency of Intense Increase of Frequency of Intense Algal Blooms in the Yellow SeaAlgal Blooms in the Yellow Sea

Nutrient Changes in the Yellow SeaNutrient Changes in the Yellow Sea

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YOC Verification ProjectYOC Verification Project（（Yellow Sea Large Marine Yellow Sea Large Marine

EcosystemEcosystem-- Ocean Color ProjectOcean Color Project））

Standard_chlorophyll_concentration

New_chlorophyll_concentration

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Location Location of the of the Ariake Ariake SoundSound

50

40

30

20

120 130 140 150

129.5 130.0 130.5 131.0

33.5

33.0

32.5

32.0

Isahaya Bay

Reclamation Area1996～

Eutrophication in Eutrophication in AriakeAriake Bay?Bay?

-- Symptom of eutrophicationSymptom of eutrophication•• Red tide increaseRed tide increase•• Low oxygen conditionLow oxygen condition

However:However:•• No nutrient load increaseNo nutrient load increase•• Dike Construction on 1998Dike Construction on 1998

諫早湾干拓（諫早湾干拓（ASTERASTER））

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IsahayaIsahaya DikeDike

Red Tide in Ariake Bay in Winter 2000Red Tide in Ariake Bay in Winter 2000--0101NoriNori (red algae) Culture(red algae) Culture40% ($200M!) Loss40% ($200M!) Loss

Comparison with Red Tide Map Comparison with Red Tide Map Produced by Nagasaki Fisheries Produced by Nagasaki Fisheries Experimental StationExperimental Station

：Observed Area）（

有明海

Nov. 9-Dec. 6, 2001

July 8-13, 2001有明海

Jul 9,2001

Nov 22,2001

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RelcamationArea

Red Red TideTidein in AriakeAriakeBayBay

SeaWiFS (2000.11.23SeaWiFS (2000.11.23--2001.4.1)2001.4.1)

0404

0303

0202

0101

0000

9999

9898

121211111010998877665544332211

Monthly SeaWiFS Chl.a 0.01 0.1 10 64

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Turbidity and Turbidity and Chlorophyll Chlorophyll Change with Change with Tidal CycleTidal Cycle

SEA

LEVEL

(cm

)

6410

1

0.050.1

31

0.10.05

3 5 9 10 11 14 16 24

5

October, 2002

700600500400300200100

SpringNeapSpring

Chl

.anL

w 5

55

Chl.a

(m

g m

-3) n

Lw

555

(mW

cm-2

μm

-1 sr

-1)

48

1216

1.01.52.02.53.020

(SeaWiFS)

Red Tide Red Tide Number Number in in AriakeAriakeSoundSound（（IsobeIsobe，，20002000））

85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00

3030--year Increase of transparencyyear Increase of transparencyValue (m) % Change

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AriakeAriake Bay HypothesisBay Hypothesis

•• Decrease of Tidal Flat (Not only Decrease of Tidal Flat (Not only IsahayaIsahayaBay)Bay)

•• Decrease of Tidal CurrentDecrease of Tidal Current•• Decrease of TransparencyDecrease of Transparency•• Increase of Available Light to Increase of Available Light to

PhytoplanktonPhytoplankton•• Increase of Red TideIncrease of Red Tide•• Increase of Low Oxygen WaterIncrease of Low Oxygen Water• D f ClDec ease of Clam

Use of Remote Sensing for Use of Remote Sensing for EutrophicationEutrophication MonitoringMonitoring

•• Large Spatial CoverageLarge Spatial Coverage•• High FrequencyHigh Frequency•• Low PriceLow Price

HoweverHowever•• Period is still limited for 10 years.Period is still limited for 10 years.•• Accuracy have to be checked.Accuracy have to be checked.•• Cause and effect is not clear.Cause and effect is not clear.

•• Combination with shipCombination with ship--observation is necessary.observation is necessary.