Coastal acidification and fishery in Japan
Tsuneo Ono (FRA)

Japan Ocean Acidification Networkongoing Japan-coast pH monitoring sites [after S. Takao/WESTPAC 2015]

M6

M7
M9
★M10
M8

M1: Oshoro Bay [Japan Sea & origotrophic;2013 – present]
M2: Tsugaru Straight [transition & origotrophic; 2014 – present]
M3: Tateyama Bay [subtropic & eutrophic;2011 – present]
M4: Shimoda Bay [Subtrophic & oligotrophic; 2011 – present]
M5: Nago Bay [Coral coast;
2000 – present]
M6: Akkeshi Bay [subarctic eelgrass swamp;
2014 – present]
M7: Miyako station [transition & oligotrophic; 2014 – present]
M8: Arasaki Station [Subtrophic & oligotrophic; 2009 - 2011]
M9:Kashiwazaki Station [Subtrophic & oligotrophic; 1982 –present ]M10:Onjuku Station [Subtrophic & oligotrophic; 1982 –present ]High diurnal/seasonal variation of pH in coastal area:
What does biota respond to? Average or Minimum?

with diurnal variation

averageThresh holdFew decades later?

100 year later?

year

modified from Yamamoto-Kawai et al.

Effects of diurnally-variable pCO2 on ezo-abalone larvae
by culture experiment [Onitsuka et al., submit.]
Constant treatments

1600

Targeted pCO2
400 µatm, 800 µatm, 1200 µatm

1400

Results of monitoring(Dotted lines)
430±15, 732±19, 1175±20 µatm

1200
1000
800

Diel cycle treatments

600

Targeted pCO2
400-1200 µatm, 800-1600 µatm

400
200
000.5

11.5

22.5

3Days after initiation of experiment

Results of monitoring(Solid lines)
420-1189 µatm, 739-1537 µatm

Results : Effects on larval fitness
2520

Mortality

There were no significant differences inmortality rate among all the pCO2treatments.

15105060

40

Abnormality
bc200caab

Abnormality rate was significantly higher
in the 1200µatm, and more inNormal
Abnormal
800-1600 µatm

ab350300

Larval shell length*250200400800

Shell length in the 800-1600 µatm wassignificantly shorter but not in
the 1200µatm.

400- 1200 8001600
1200

pCO2 (µatm)[Onitsuka et al., submit.]

Results 2: Effect of integral pCO2 on larval fitness
50

Abnormality

40

The aragonite saturation state aroundΩ=1.0 is equivalent to 1100 µatm pCO2.

30

Integral pCO2 over 1100 µatm=∑ 𝑷 − 𝟏𝟏𝟏𝟏 𝒊20100300

P: pCO2 over 1100 µatmi: exposed hours to pCO2 over 1100 µatm

280260240

Larval shell length2202000

2000 4000 6000 8000

Integral pCO2 over 1100 µatm(µatm h)Open markers: diel cycle treatments
Solid markers: constant treatments

Abnormality rate increased withincrement of integral pCO 2 over 1100
µatm .
Larval shell length decreased as integral
pCO2 over 1100 µatm increased.

High diurnal/seasonal variation of pH in coastal area:
What does biota respond to? Average or Minimum?

with diurnal variation

averageThresh holdFew decades later?

100 year later?

year

modified from Yamamoto-Kawai et al.

Oshoro Bay station, Hokkaido
2013 summer

pH amplitude:
avg. 0.18 ± 0.08
max 0.44
min 0.08

2014 summer

pH amplitude:
avg. 0.28 ± 0.19
max 0.83
min 0.05

another example: Arasaki Station [FRA]

pCO2 monitoring tank(1.5m depth x~0.5h residence time)eelgrass
bed
100m

water pump line
mouth = 3m depth(average)
brown algae bed©KIMOTOElectｒonic

1-year composite pCO2 variation
pCO2 monitoring (continuous pCO2
monitoring system by Kimotoelectronic) was occupied
intermittently from 2009 to 2011 tomake composite 1-year time series.

1-year composite data・significant seasonal dependence in the amplitude of diurnal pCO2 variation#winter (Nov. – Mar.)#spring (May –mid July)#summer (mid July – early Sept.)#autumn(mid Sept.-Oct.)・Annual pCO2 maximum:~150 ppm~200ppm>300ppm (max. 400)
~200ppm

daily avg. 600ppm
with diurnal variation: >800ppm

result of 24-hour pCO2 monitoring

temporal pCO2 increse
further +200ppm

avg =400 ppm
amplitude= ±60ppm

total diurnal pCO2 variation........about 300 ppm

Existence of local hot spot of pH and pCO2 among the Arasaki station
pCO2
(pH)

411ppm
(8.02)

329ppm(8.10)？

720ppm
(7.84)

390ppm(8.04)
ArasakiSta.
217ppm
(8.23)

526ppm
(7.93)

different biotic response between "natural eutrophication"and "polluted eutrophication"
polluted eutrophication(arasaki district)

pCO2

pCO2

natural eutrophication(inner-Bay, estuary etc.)

Summary: present knowledge on ocean acidification
In the coastal waters around Japan
1] pH decrease in Japan coast: -0.003/y at one station, but should be subject tohigh local variation (more long-term data needed!）2] existence of high diurnal / seasonal variation of pH even in one site, andsome fisheries species exhibit high sensibility not against daily average but daily minimum pH(or daily integral of pH deficit from the level equivalent to Ωara =1 )We need high-res., continuous pH monitoring to acquire this information.
3] detailed OA-mapping observation showed that there are many local hot spot of pCO2 (pH)along the Japan coast as the result of the anthropogenic eutrophication. This may cause
severe effect to local biota (incl. fisheries resources) when considering historical biologicaladaptation.
4] Anthropogenic CO2-derived OA, naturally eutrophicated OA, and anthropogenically-eutrophicated OA affect to ecosystem DIFFERENTY.
We need multi-parameter monitoring data (e.g., nutrient and Chla in parallel with pH) todetermine different cause of ocean acidification.