EMECS 9 2011 Aug 28

Satoshi Chiba

Faculty of Environmental and Information Sciences,

Yokkaichi University, Mie, Japan

Yasuhiro Shimizu , Hideki Kokubu, Hiroshi Tachi

Mie Prefecture Fisheries Research Institute, Mie, Japan

Pearl Culture Waste, Nutrient Load from Land

or Loss of Tidal Flat, What is the Cause of the

Deterioration and what should be controlled

for the Restoration of Ago Bay Environment?

Ｎ

0 1 2 3 4km

Ugata

Inlet

Shinmei

Inlet

Tategami

Inlet

Funakoshi

Inlet

Hamajima

Inlet

Location, Landscape and Bathymetry of Ago Bay

Owase

Kumano

Ago Bay

Tsu

Ise Bay

Yokkaichi

Pacific Ocean

N

Nagoya

Islands of Japan

Ago Bay

Pacific

Ocean

Ise

Bay

Environmental Problems of Ago Bay

1. Organic Pollution in Sediment

2. Hypoxia in Water Column

3. Reduction of Benthos Diversity and Density

4. Break Out of Toxic Plankton and Infectious

Disease for Pearl Oyster

History of Environmental

Matters

1900 1920 1940 1960 1980 2000 2020

Nutrient Load

From LandCOD

in Sediment

COD in

Water Colum

Pearl

Production

DO in Water

near Seafloor

Reclamation

Red Tide

Hypoxia in water column

Toxic Dinoflagellate,

Infectious Disease of

Pearl Oyster

YEAR

Mass Mortality of Pearl Oyster

Birth of Pearl

Culture

WW2

70mg/g-dw

30mg/g-dw

50ton/y

100tonN/y

200tonN/y

5ton/y

Nutrient Load

From Outer Sea

Previous Research for Environment of Ago bay

Research for the organic pollution by the pearl culture

Research for the material budget around Ago bay

• Y.Sawada and M.Taniguchi (1968)

• H.Uemoto (1981)

• S.Ueno, et.al. (2000)

• others

• Ago Bay Project (2003-2007)

Objectives of This Study

1. To quantify the effect of several environmental

factors on organic pollution of sediment and

hypoxia in seawater of Ago bay, with the aid of

numerical models.

2. To provide helpful data for policy making and

restoration activity in the future.

Hydrodynamic Model

Physiology Model

Of Pearl Oyster(3-Generation Model)

Pelagic Ecosystem

Model

Early Diagenesis Model

of Sediment

Numerical Models of Ago Bay

Not Coupled.

Coupled

Coupled

Mean Distance Between Rafts : 38m

Raft Width : 6m (typical)

Me

an

Wa

ter

De

pth

= 1

0m

Enhanced

Sedimentation

Water Surface

Sediment

Waste

Deposition

Localization of POC Sedimentation of

Suspended Pearl Culture

Trapping of

PlanktonPearl Oysters

DispersionReduced

Sedimentation

Anoxia

Block Division of Sediment Model

All the waste from the pearl

culture is assumed to settle

on the culture area.

Hamajim

a

Ugata

Shinmei

Tategami

GozaFunakoshi

Fukaya

Wagu

Ｎ

12

3

4

5

6

789

10

Non-Culture

Area

Culture

Areaone-tenth of N-C Area

Sediment

Model

Pelagic

Ecosystem

Model

One Block

Vertical section (image)

Ｎ

Ugata

WD=12.8m

Tategami

WD=9.0m

Takonobori

WD=26.7m

0m

20m

40m

Water Depth

Location of Observation Sites

J A S O N D J F M A M J J A S O N D

J A S O N D J F M A M J J A S O N D

Comparison of Dissolved Oxygen in Water Column

Observed Data at Takonobori Unit（mgO2/liter）2003 July 1 to 2004 Dec.31

Computational Result for Takonobori

Observed Data at Tategami

Computational Result for Tategami

0

5

10

15

20

25

30

0 10 20 30 40 50

Dep

th(cm)

POC(mgC/g-dw)

Tategami

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 10 20 30 40 50

Dep

th(cm)

POC(mgC/g-dw)

Takonobori

Non-Culture Zone

Culture Zone

Observation

Comparison of POC in Sediment

0

5

10

15

20

25

30

0 1 2 3

Dep

th(cm)

FeS(mgS/g-dw)

Tategami

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 1 2 3

Dep

th(cm)

FeS(mgS/g-dw)

Takonobori

Non-Culture Zone

Culture Zone

Observation

Comparison of FeS in Sediment

Calculation Cases

Case Name

Heterocapsa

Circulari

Squama

Nutirent

Load

from

Land

Nutrient

Load

from

Outer

Sea

Factor for

Number of

Cultured

Pearl

Oysters

Tidal

Flat

Returning

Factor of

Nutrient

from TF

nonhetero None 100% 100% 1.0 None

land50%

(nh)None 50% 100% 1.0 None

ocean50%

(nh)None 100% 50% 1.0 None

akoya5(nh) None 100% 100% 5.0 None

tflat0(nh) None 100% 100% 1.0 Included 0.0

tflat1(nh) None 100% 100% 1.0 Included 1.0

hetero Included 100% 100% 1.0 None

tflat0(h) Included 100% 100% 1.0 Included 0.0

Note : (h) and (nh) indicate condition with and without Heterocapsa Circularisquama.

Tidal flat area : 266 hectare

1.18

1.02

1.10

1.10

1.14

1.23

0.8 1.0 1.2 1.4

nonhetero

land50%(nh)

ocean50%(nh)

akoya5(nh)

tflat0(nh)

tflat1(nh)

GPP(gC/m2/day)

Gross Primary Production and POC Loading on Sea FloorAverage of Bay Head Area in Warm Months (May to October)

2.126

1.653

1.882

1.446

1.938

2.062

0.116

0.067

0.105

0.231

0.100

0.122

0.0 1.0 2.0 3.0

POC Loading (tonC/day)

POC Loading without Culture Waste

POC Loading due to Culture Waste

decrease!!

Nitrogen Budget in Ago Bay

360

350

194

274 13 160

127

Unit：ton-

N/year

Case : Nonhetero

Elution

Culture

WastePON

Sea Floor

Permanent

Sedimentation

Land

(without toxic plankton)

287=

353

357

194

217 31 135

113

Case : Akoya5

Elution

Culture

WastePON

Sea Floor

Permanent

Sedimentation

Land

(Increased oyster density)

Outer

Sea

Outer

Sea

248=

0.21

0.16

0.18

0.14

0.19

0.20

0.32

0.23

0.29

0.37

0.29

0.32

0.0 0.1 0.2 0.3 0.4 0.5

nonhetero

land50%(nh)

ocean50%(nh)

akoya5(nh)

tflat0(nh)

tflat1(nh)

POC Flux (gC/m2/day)

POC Flux of Non-Culture Area

POC Flux of Culture Area

POC Flux to Sea Floor around Bay Head Area

Culture Area Non-Culture Area

POC FluxPOC Flux

Increase,

but slightly!

0.08

0.03

0.02

0.02

0.06

0.09

0.26

0.18

0.0 0.1 0.2 0.3 0.4

nonhetero

land50%(nh)

ocean50%(nh)

akoya5(nh)

tflat0(nh)

tflat1(nh)

hetero

tflat0(h)

Hypoxic Area (km2)

Average Hypoxic Area of

Seafloor during May to October

0.0

1.0

2.0

3.0

4.0

J F M A M J J A S O N D

Hypoxic

Are

a

(Km

2)

hetero

0.0

1.0

2.0

3.0

4.0

J F M A M J J A S O N D

Hyp

oxic

Are

a

(Km

2)

nonhetero

Hypoxic Area of Seafloor

Effective

for hypoxia

reduction

0.91

0.60

0.75

0.26

0.78

0.99

1.31

1.13

1.25

1.25

1.25

1.21

0.0 0.5 1.0 1.5 2.0

nonhetero

land50%(nh)

ocean50%(nh)

akoya5(nh)

tflat0(nh)

tflat1(nh)

FeS(mgS/g-dw)

Non-Culture Area Culture Area

18.8

15.5

16.6

12.4

17.3

18.8

26.3

20.9

23.2

26.6

23.9

26.5

10 15 20 25 30 35

nonhetero

land50%(nh)

ocean50%(nh)

akoya5(nh)

tflat0(nh)

tflat1(nh)

POC (mgC/g-dw)

Non-Culture Area Culture Area

Average POC in Upper 3cm of

Surface Sediment at Tategami

Average FeS in Upper 3cm of

Surface Sediment at Tategami

Evaluation of Environmental Factors

Environmental

Factor

Hypoxia in

Water Column

OM Accumulation

in Sediment of

Non-Culture Area

OM Accumulation

in Sediment of

Culture Area

Nutrient Loading

from LandE E E

Nutrient Loading

from Outer SeaE E E

Pearl Culture R R E

Tidal Flat R R R

Heterocapsa

CircularisquamaE U U

E : Enhance, R : Reduce, U : Unknown

• This study with new computer models quantified

the effect of several environmental factors and

brought some new insights for the environmental

deterioration of Ago bay.

Summary

• The nutrient loading from the drainage area and

the outer sea are found to be the most probable

cause for the environmental change for recent

years, and it corresponds to the actual change of

nutrient loading.

Summary (continued)

• Although the pearl culture enhances the organic

pollution in the sediment near the raft, it also

reduces the organic pollution in the non-culture

area and the hypoxia in the water column.

Summary (Continued)

• The effect of tidal flat for environmental change

was not significant. It is clear that the present

model neglects the biological aspect for the tidal

flat such as the role of the nursing for marine

creatures. This suggests the need for the

simulation with the higher trophic model.

Summary (Continued)

END

Thank you for your cooperation.

Information of Ago BayGovernmental

body

Shima City

Drainage Area abt.70km2

Water Basin

Area

abt.25km2

Population in

Drainage Basin

abt.36,000

Number of

tourists

abt.10million/y

Pearl Oysters in culture net

Maintenance Work (Shell Cleaning)

Harvest of Pearls

Pearl Oyster(pinctada fucata

martensii)

All photos were taken

by T.Atsumi.

Culture Raft

Number of groups

farming pearl culture

abt.500

Number of pearl oysters abt.100 mill.

Population density of p.o. abt.4 /m2

Information of Pearl Culture

Hypoxic Water Distribution

2003 Sep.11

2003 Aug.21 2003 Aug.26

3 mgO2/L

2 mgO2/L

Dissolved Oxygen data were

measured at 26 sites in the bay

from observation vessel and

processed as 3-D contour map.

Bay Mouth Bay Mouth

Bay Center

Bay Head

Bay Mouth

Contour Level

Seasonal Change of Benthos Population

Benthos Data (2002)

Unpublished data for the benthos population by Naoa Hata of

Mie Prefecture Fisheries Research Institute, 2002.

0

1000

2000

3000

4000

5000

1 2 8 9 10 11 12 13 14 15 16 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Nu

m.o

fIn

div

idu

als

(1/m

2)

Site No.

2002 April

0

1000

2000

3000

4000

5000

1 2 8 9 10 11 12 13 14 15 16 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Num

.of In

div

idu

als

(1

/m2

)

Site No.

2002 September

Protochordate

Echinodermata

Pogonophora

Arthropoda

Mollusca

Tentaculata

Annelida

Sipuncula

Nemertea

Platyhelminthes

Coelenterata

April September

Wet

Weight17.1 g/m2 10.7 g/m2

Number of

Individuals 3098 /m2 764 /m2

Feature of Numerical Models

1. Three-dimensional, Time Dependent, Hydro-Static Model

2. Sea Surface Conformed Grid System

3. Quickest Scheme for Advection

4. Time Splitting Integration for External and Internal Modes

5. One Equation Turbulent Model (M & Y Level 2.0 Modification)

1. (ERSEM Like) Low Trophic Model

2. Coupled with Pearl Oyster Model

3. Coupled with Sedimentary Model

1. One-dimensional Early Diagenesis Model

2. Ideas of H.Fossing (2004) and P.Berg (2003) are largely

borrowed for set-up.

Pelagic Ecosystem Model (original)

Sedimentary Model (original)

Hydrodynamic Model (original)

X

ZY

20

0m

Region I (Offshore Region,

X axis : Eastward, Y axis : Northward)

Region II (Core of

Ago Bay Region)Region II

Grid System of Numerical Models

Lo

we

r P

art

(F

ixe

d)

Up

pe

r P

art

(Mo

va

ble

) High Water

Low Waterabt.2m

7grids

28m

18grids

abt.3m

Vertical Arrangement of Grids

Model of Pelagic Ecosystem

Diatom

Dinoflagellates

Zooplankton

DIP

DIN POP

PON

Dissolved

OxygenPhotosynthesis

respiration

Settling

Effluent

Consumption by sediment

Predation

Uptake

ReleaseDeath

Atmospheric

OxygenSea Surface

Sediment

Sun Ray

Exchange with

Outer Sea

POC

DOP

DON

DOC

Consumption by OM dissolution

Dissolution

Dissolved

Organic Matter

Particulare

Organic Matter

Inorganic

Nutrient

Resuspension

Pearl Oyster

Egestion

Inflow from

Drainage Basin

Waste of

Shell Cleaning

DIP

DINCell

Quota

DIN, DIP

respiration

respiration

Effluent

Settling

Predation

Egestion

Mortality

Dis-

solution

Dis-

solution

Release

Egestion

Model Geometry (1-D)

Sediment ModelSea Bed

Computational Cell

z

DBL

Bottom Boundary

Upper Boundary

Early Diagenesis Model

30 c

m in

dep

th, 60 G

rid

Po

ints

Bio-GeoChemical

Reactions

J A S O N D J F M A M J J A S O N D

J A S O N D J F M A M J J A S O N D

Computational Result for Tategami

Comparison of Salinity in Water Column

Observed Data at Tategami

Observed Data at Takonobori Unit（PSU）2003 July 1 to 2004 Dec.31

Computational Result for Takonobori

2003 July 1 to 2004 Dec.31

Computational Result for St.B

Comparison of Sea Water Temperature

Observed Data at St.B

Computational Result for St.A

Observed Data at St.A Unit（Celsius）

Note: Heterocapsa Circulary Squama

included in the computation.

Unit（μg/liter）

2003 July 1 to 2004 Dec.31

Computational Result for St.B

Comparison of Chlorophyll

Observed Data at St.B

Computational Result for St.A

Observed Data at St.A

Note: Heterocapsa Circulary Squama

included in the computation.

0

5

10

15

20

25

30

0 1 2 3

De

pth

(cm

)

FeS(mgS/g-dw)

Tategami

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 1 2 3 D

ep

th(c

m)

FeS(mgS/g-dw)

Ugata

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 1 2 3

De

pth

(cm

)

FeS(mgS/g-dw)

Takonobori

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 10 20 30 40 50

De

pth

(cm

)

POC(mgC/g-dw)

Tategami

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 10 20 30 40 50

De

pth

(cm

)

POC(mgC/g-dw)

Ugata

Non-Culture Zone

Culture Zone

Observation

0

5

10

15

20

25

30

0 10 20 30 40 50

De

pth

(cm

)

POC(mgC/g-dw)

Takonobori

Non-Culture Zone

Culture Zone

Observation

Comparison of POC and FeS in Sediment

Gross Primary Production- Comparison with Observation Data -

Solid Line : Computational Results for 2004

Solid Circle : Observation data in 2009

Calculation Case : nonhetero

0.0

1.0

2.0

3.0

4.0

5.0

GP

P (

gC/m

2/d

ay)

J F M A M J J A S O N D

0.0

1.0

2.0

3.0

4.0

5.0

GP

P (

gC/m

2/d

ay)

Takonobori (Bay Center) Tategami (Bay Head)

J F M A M J J A S O N D

0

2

4

6

8

10

12

J F M A M J J A S O N D

Dis

so

lve

d O

xyg

en

(m

gO

2/L

)

nonheteroland50%ocean50%akoya5tflat0observation data

0

2

4

6

8

10

12

J F M A M J J A S O N D

Dis

so

lve

d O

xyg

en

(m

gO

2/L

)heterononheteroobservation data

3mgO2/L

Dissolved Oxygen in Water Column near Sea Floor at Tategami

Data of 2004

11.4

8.4

10.9

4.4

15.8

27.3

19.0

25.2

13.3

40.3

0 10 20 30 40 50

1

2

3

4

5

Blo

ck N

o.

Eflux of H2S (mgS/m2/day)

Non-Culture Area Culture Area

Ugata

0

2

4

6

8

10

0 100 200 300 400

De

pth

(cm

)

H2S(μM)

Culture Area

1112131415

0

2

4

6

8

10

0 100 200 300 400

De

pth

(cm

)

H2S(μM)

Non-Culture Area

1 2 3

4 5

Average H2S Eflux

During Warm MonthsVertical Distribution of H2S

on September at Tategami

Tategami

All data : Nonhetero Condition

Increase of Nutrient Load from

Drainage Area & Outer Sea

Excess Deposition of Organic

Waste from Pearl Culture

Hypoxia in

Water Column

Decrease of Decomposition

rate of OM and Vertical-Mixing

Capability of sediment

Enrichment of

Sediment

Attenuation of Benthos

Increase of Toxic

Dinofllagelate

Increase of Anoxic

Decomposition

The Sequence of Environmental Deterioration

in Ago Bay (Estimation)