La mer 53 : 43-51, 2015
Société franco-japonaise dʼocéanographie, Tokyo

Observation of near-inertial internal waves in the abyssal Japan Sea
TOMOHARU SENJYU

Abstract: Observation with a moored Acoustic Doppler Current Profiler (ADCP) set to a very
short measurement interval revealed vertical propagation of near-inertial internal waves (NIW)in the abyssal Yamato Basin in the Japan Sea. Flow and temperature measurements showed asinusoidal variation having near-inertial period associated with NIW. From the polarization of flow
vectors, vertical and horizontal wave numbers of the NIW were estimated to be 1.741×10-3 m-1
and 2.563×10-4 m-1, respectively. Phase propagation of the NIW was downward at speed of 5.34×
10-2 ms-1, indicating an upward group velocity. Back-tracing of the energy ray path of NIW
passing through the observation point shows that the observed NIW were the bottom-reflected
waves. The bottom reflected waves were the downward-propagating NIW generated in the upper
layer. An event of clockwise rotation of wind vectors was suggested as a cause of the observed
NIW.
Keywords : Yamato Basin, ADCP, short measurement intervals, vertical propagation

1.

Introduction(Fig. 1), has its own thermohaline circulation

Internal gravity waves with frequency close tosystem (GAMO and HORIBE, 1983; SENJYU et al.,the local inertial frequency (near-inertial internal

2002). NIW have been frequently reported in the

waves, NIW) are ubiquitous in the world oceans

Japan Sea not only in the upper layer (KANARI et(WEBSTER, 1968; FU, 1981). NIW have beenal., 1987; LIE, 1988; KIM et al., 2001; KIM et al., 2005;

considered to be an important agent for mixing in

PARK and WATTS, 2005; OKEI et al., 2009; IGETA etthe ocean interior (HIBIYA et al., 1996) whichal., 2009, 2011; BYUN et al., 2010), but also in thecontrols the intensity of the global-scale thermo-

deep layer (TAKEMATSU et al., 1999; SENJYU et al.,haline circulation (TOOLE and McDOUGALL, 2001);

2005; MORI et al., 2005). Considering that the

however, NIW structure and propagation proc-

frequency of internal gravity waves (ω) must be

esses in the deep sea have not been clarified.

in the band between local inertial frequency (f)It is known that the Japan Sea, a semi-enclosed

and buoyancy frequency (N) (GILL, 1982), we

marginal sea in the northwestern North Pacifichave some advantages to NIW observation in theJapan Sea. First, the frequency of NIW generated

Division of Earth Environment Dynamics,
Research Institute for Applied Mechanics, Kyushu
University
6-1 Kasuga-Koen, Kasuga City, Fukuoka 816-8580,
Japan
e-mail: senjyu@riam.kyushu-u.ac.jp

in there is limited to 0.837-1.149×10-4 s-1, becauseof the Japan Sea’s latitudinal extent (35˚-52˚ N).
Second, deep water in the sea, the Japan Sea
Proper Water, has very narrow ranges oftemperature and salinity (WORTHINGTON, 1981),

44

La mer 53, 2015

which results in a buoyancy frequency on thesame order of f (typically 1.0-5.0×10-4 s-1 below

1000 m). These facts indicate that NIW in theabyssal Japan Sea have a narrow frequency
range. In addition, tidal flows in the Japan Sea are
generally weak (SENJYU et al., 2005). This factindicates little contamination from tidal motions.
The weakness of tidal flows also indicates that themost of sub-diurnal variations in the Japan Sea
are the near-inertial motions, which suggests thatthe intensity of the basin-scale thermohaline
circulation in the sea is mainly controlled by thenear-inertial flows associated with NIW, analogous to the global-scale thermohaline circulation.
One reason that the behavior of NIW in deep
water has not been clarified is that deep flow
observations with high spatial and temporal
resolution are not common. For example, in theJapan Sea, it has been common in long-termcurrent monitoring for serial single-layer current
meters to be spaced at tens to hundreds of metersin the vertical, with 30-60 minute sampling

Fig. 1 Observation site. Contour lines indicate
water depth in meters. Star and circle indicate Sta.
SH of ADCP mooring and Sta. KS3638 of JMA,
respectively. YB and YR denote the Yamato Basinand Yamato Rise, respectively. The ray-tracing
was done in the section along the solid line. The
area is enlarged map of the square in the inset
showing the Japan Sea.

intervals (SENJYU et al., 2005). Therefore, we

upward looking at 2650 m. To detect NIW

made special observations to capture NIW

propagation, we set bin size and measurement

propagation in the abyssal Japan Sea, using aintervals at 4 m (with the first bin at 6.2 m) andmoored10 seconds, respectively. The nominal accuracy of

Acoustic

DopplerCurrent

Profiler(ADCP) set to a very short measurement

the ADCP is ±0.5% of water velocity relative tointerval. Although the period of observation was

the instrument ± 0. 5 cms-1. The accuracy andonly about 2 days, we successfully observed

precision of flow direction are ±2.0˚ and ±0.5˚,

vertical NIW propagation in the deep sea. This

respectively.

paper describes the results of the observation and

The posture of ADCP during the observation

discusses the NIW structure, propagation, andwas very stable. Pitch and roll angles monitored

generation in the abyssal Japan Sea.

by a tilt sensor in the instrument were within ±1˚throughout the mooring period. Nevertheless, no2.

Observation

flow data were obtained by the equipment for

The ADCP (300 kHz Workhouse, Teledyne

layers farther than 50 m because of weak acoustic

RDI) was deployed at Sta. SH in the Yamato

echo intensity, though the nominal observation

Basin of the Japan Sea (38˚ 17.05’ N, 135˚ 50.0 6’ E)

distance was set to 100 m. In addition, data at theat 07:12 on 13 May and recovered at 05:39 on 15

first layer (2644 m) were noisy. Therefore, we

May 2013 by TR/V Nagasaki Maru of Nagasaki

analyzed the velocity profile in the 40 m range

University (Fig. 1). The ADCP was mooredfrom 2600 to 2640 m (lay ers 2-12 of the

Observation of near-inertial internal waves in the abyssal Japan Sea

45equipment, for a total of 11).
Six successive velocity profiles at 10-second
intervals were averaged to yield 1-minute interval data. Furthermore, 5-minute running mean
was applied to the 1-minute data to reduce shortterm fluctuations. The size of the averaging time
window (5-minute) was determined try anderror to reserve the signal of vertical propagationof NIW. Owing to the averaging, standard
deviation in a current measurement was reduced
to 0. 16 cms-1. The available data length is 45
hours 54 minutes from 07:43 on 13 May to 05:37 on
15 May 2013.
In addition to the flow observation, temperature at 2650 m was measured with a sensor
embedded in the ADCP transducer head at thesame sampling intervals as flows. Though thenominal precision of the sensor is ±0.4˚C and theaccuracy and time constant of the sensor are
unknown, the temperature measurements areuseful for the present study because the relative

Fig. 2 Time series of velocity at 2604, 2620, and 2636
m and temperature at 2650 m. Gray thin and blackbold lines in velocity show east-west (u) andnorth-south ( ) components, respectively. Thinstrait lines in each panel denote the linear trend
throughout the observation period.

values of temperature are available by the
resolution of the sensor, 0.01˚C. The same proce-about 20 hours, superimposed on the linear trend,

dure of flows was applied to the temperature

was clear in each layer. The phase of sinusoidal
variation indata.

led by about 90˚ than that in u,

showing a clockwise change of flow direction.
3.

Results

Similar periodical variation to that of flows wasTime series of east-west (u) and north-south

found for temperature. In addition, vertically-(ν) components of velocities at 2604, 2620, andcoherent fluctuations with relatively large ampli-

2636 m are shown in Fig. 2, along with tempera-

tude were occurred intermittently, for example ature measurements (T) at 2650 m. Flows at eachvelocity shift in 16:30-17:00 on 13 May and a jumplayer exhibited similar temporal variations toineach other, showing a prevailing barotropic flow.

short period fluctuations in flow and temperature

Speed and direction of the vertically-averaged

measurements are probably due to noise, whichmean flow for the observation period were 2.73

amplitudes are near the measurement threshold

cms

and tend to be large as increase of distance from-1

and 315. 8˚, respectively. This northwest-

ward flow may be part of the cyclonic circulationin 09:00-10:00 on 14 May. However, most of

the equipment.

in the Yamato Basin (SENJYU et al., 2005), though

For a rough estimate of the dominant period of

the observed flows showed a linear temporalvariation, we separated the periodical compo-

trend.

nents in u, , and T (hereafter uʼ, ʼ, and Tʼ) fromA sinusoidal flow variation with a period ofbackground variations by subtracting the tempo-

46

La mer 53, 2015
Table 1 Mean relative angles of the velocity vector at each layer to the velocity at 2640 m

Depth (m)

2636

2632

2628

2624

2620

2616

2612

2608

2604

2600

Relative Angle (˚)

0.86

1.83

0.88

2.06

2.47

1.54

2.29

3.06

3.93

3.17

ral linear trends from the measurements, thencalculated auto-correlation functions for uʼ, ʼ, andTʼ The linear temporal trend for flows wascalculated from the vertically-averaged flow byleast square method. The estimated periods(frequencies) of uʼ and ʼ as the mean for the allobservation depths were 1118. 3 minutes ( u =9.364×10-5 s-1) and 1192.6 minutes ( v=8.781×10-5 s-1), respectively, and the estimated period(frequency) of Tʼ at 2650 m was 1136 minutes( T = 9. 218 × 10-5 s-1). Since the local inertial
period (frequency) at the observation site is1158.9 minutes (f =9.036×10-5 s-1), the observed
periodical variations of flows and temperature aremostly attributable to NIW. It may seem strangethat the frequency of ʼ is lower than the local
inertial frequency. This is likely due to an
insufficiently long observation period for precise
estimation of near-inertial motions, though a

Fig. 3 Relationship between the mean relative
angles of velocity vector to that at 2640 m ( )and the vertical distance from 2640 m ( D). The
regression line is shown by the strait line.

region of negative relative vorticity can trap sub1982). As a typical example of vertical NIW

inertial frequency motions (KUNZE, 1985).
Because of the noisy short period fluctuations,propagation, time-depth diagrams of uʼ and ʼ are

it is hard to confirm the polarization relation in ashown in Fig. 4 for 11: 00-17: 00 on 14 May.

snapshot profile of uʼ andʼ. Therefore, we

Vertical phase propagation from upper to lower

calculated the angles between the velocity vector

layers is discernible in both components. Similar

at each layer and that at 2640 m (relative angles

vertical phase propagations in uʼ and ʼ to that inreferred to the deepest layer velocity vector),

Fig. 4 were detected several times during theand averaged them for the observation period

observation period.

(Table 1 and Fig. 3). The mean relative angles
exhibited positive values throughout the observa-

4.

tion depths, indicating a clockwise rotation of

4.1 Structure of the NIW

velocity

Discussions

layers.

At first, vertical phase speed and wave number

Furthermore, the mean relative angles tend toof the NIW were tried to estimate from verticaldecrease from 3-4˚ at 2600-2608 m to less than 1˚cross-correlation functions for uʼ and ʼ. However,vectors

intheshallower

at 2628 and 2636 m. This polarization suggests a

broad peaks in the cross-correlation functions

downward phase propagation of NIW (GILL,

prevented

us

from

a

reliableestimation.

Observation of near-inertial internal waves in the abyssal Japan Sea

47

Fig. 5 Vertical profile of squared buoyancy frequency (N2) at Sta. KS3638 of JMA.
Fig. 4 Time-depth diagram for uʼ (upper) and ʼ(lower) during 11: 00 to 17: 00 on 14 May 2013.
Negative values were denoted by dashed contours. Broken line in lower panel shows theestimated propagation speed 5.34×10-2 ms-1.

higher than the local inertial frequency at theobservation site, then vertical phase speed CZ (=/m) is estimated to be 5.34×10-2 ms-1 (broken

line in the lower panel of Fig. 4). Such fast phasepropagations cannot be captured by typical deepsea mooring observations with few current

Therefore, we estimated the vertical wave length

meters of tens to hundreds of meters verticalof the NIW from the polarization relation; Fig. 3

spacing and 30-60 minutes sampling intervals.

shows a clear linear relationship between therelative angle (Unfortunately, there were no stratification data

) and distance from thenear the observation site during the mooringreference depth 2640 m ( D), with the correla-

period. Therefore, we inferred squared buoyancy

tion coefficient of +0.89. The polarization relation

frequency N2 in the abyssal Yamato Basin fromdetermined by least square method istemperature and salinity data at Sta. KS3638(38˚16.52’ N, 135˚ 50.69’ E), obtained by the Japan

D = 10.025(1),which shows the vertical wave length

Meteorological Agency (JMA) on 4 November
2012 (Fig. 1). N2 from 2600 to 2640 m is 2.554--3m (vertical wave number =1.741×10
D at=360˚. If we takethe mean ofu andz of 3609-1m ) as-5=9.291×10

-1

s

as

T, reasonable frequencies

3.385×10-8 s-2 (Fig. 5), with mean 3.022×10-8 s-2
corresponding to the buoyancy frequency (peri-od) of 1.739×10-4 s-1 (602.4 minutes).

Using the values of f, , and N2 above, the phase48

La mer 53, 2015

propagation angle of the NIW from the horizontal

for the entire region (Fig. 1). Southward( ) was estimated at 81.6˚ frompropagation of the observed NIW is qualitatively
supported by the relationship between ʼ, and Tʼ
(2).

in Fig. 2; when ʼ was negative (southward) Tʼtended to decrease because of upward advection

Since the above relationship also represents

the aspect ratio of NIW (m2 / H2, wherehorizontal wave number),-4

NIW was estimated to be 2. 563 × 10
(horizontal wave lengthis

H

H of the observed-1m

H=24512 m).

of cold water in the lower layer, and vice versa(see Fig. 8.4 in GILL, 1982).
The ray-tracing shows that the NIW passing
through a point 2620 m of the observation sitewith upward group velocity are bottom-reflected
waves (Fig. 6), which were downward-propagat-

4.2 Propagation of the NIW
Since phase propagation of the observed NIW

ing NIW incident on the bottom about 1. l km
north of the observation site. Further back-was directed from upper to lower layers, thetracing suggests that the observed NIW weredirection of the group velocity must be upward

generated in the upper layer, rather than theaccording to the linear wave theory (GILL, 1982).

seabed around the observation site.

This suggests that the observed NIW weregenerated at the seabed or were bottom-

4.3 Generation of the NIW

reflected waves. To examine the bottom genera-

It has been reported that near-inertial motions

tion/reflection possibility, we back-traced theobserved in the upper layer of the Japan Sea

NIW energy ray from the observation site. The

were associated with atmospheric disturbances

WKB approximation is not applicable because of(KIM et al., 2005; OKEI et al., 2009; IGETA et al., 2009,

the large vertical wave length of the NIW

2011). Part of the near-inertial motions generated

comparable to the length scale of density

in the upper layer can propagate down into thestratification N. However, variation of N is on theorder of 10-4 s-1 below 1000 m (from 1.153×10-4

deep layer (ALFORD et al., 2012), though most ofwind energy injected into the ocean is confined in

s-1 near the bottom to 5.140×10-4 s-1 at 1116 m,

the surface mixed layer (FURUICHI et al., 2008).

Fig. 5). Therefore, we considered that N is almost

Therefore, we examined wind conditions before

constant and assumed that the ray-tracing

and during the observation period using the Gridmethod is locally applicable below 1000 m.

Point Value/Meso Spectral Model (GPV/MSM)

Since NIW can only freely propagate equator-

data provided from JMA. The GPV/MSM isward from its generation area (GＡＲＲＥＴＴ, 2001)

hourly operational weather forecasting data withand the critical latitude at which the local inertial

spatial resolutions of 0.05˚ and 0.0625˚ in latitude

frequency f is the same as the observed NIW

and longitude, respectively.

frequency

is 39˚35.3’ N, the generation or

The time series of wind speed averaged overreflection region of the observed NIW is likely tothe area in Fig. 1 (38˚-40˚ N, 135˚-137˚ E) is

be north of the observation site. Therefore,shown in Fig. 7a for the period of 8-15 May 2013.

tentatively, the backward ray-tracing was done

Although the wind speed was less than 10 ms-1

northward in the section along 135˚50.0’ E withthroughout the analysis period, a marked event

origin 38˚17.0’ N (observation site) on the -plane,assuming the profile of N2 at Sta. KS3638 of JMA

occurred in 10-11 May. Fig. 7b shows the timeseries of wind vectors for the 20-hour high-passObservation of near-inertial internal waves in the abyssal Japan Sea

49

filtered component including the local inertial

more than 40% of the total wind speed in thisperiod variations. A clockwise change in wind

period (Fig. 7a). Since surface near-inertial

direction is clear during the period from 13:00 on

currents are most efficiently enhanced when

May 10 to 12:00 on May 11. This clockwise change

windvectorrotates

inertially(LARGEandin wind direction was dominant variation because

CRAWFORD, 1995), this atmospheric event may be

the high-pass filtered component accounts fora cause of the observed NIW.
Another possible process of the NIW generation is geostrophic adjustment accompanied withinstabilities of the mean flow (TANG, 1979). Northof the observation site, the subarctic front in theJapan Sea lies about 40˚ N with significant
variability due to mesoscale eddies generated byinstability (ISODA, 1994). Besides, internal lee
waves may be excited by interactions between
deep flows and the Yamato Rise (NIKURASHIN and
FERRARI, 2010), because the subarctic front
intersects the Yamato Rise throughout the year
(PARK et al., 2007) and the mesoscale fluctuationsin the subarctic front influence the deep flow field(SENJYU et al., 2013). The high level of internal
wave energy in the Yamato Basin (MORI et al.,2005; SHCHERBINA et al., 2003) is partly attributable

Fig. 6 Ray path of the southward propagating NIW
passing through a point 2620 m of the observationsite in the section along the solid line in Fig. 1.

to the instability of flows along the subarctic front
and the Yamato Rise. However, the observed
NIW may be not the case because of its large

Fig. 7 Time series of the GPV/MSM wind averaged over the area 38˚-40˚ N, 135˚-137˚ E (Fig. 1) for the periodof 8-15 May 2013. (a) Wind speed (bold line) and that for the 20-hour high-pass filtered component (thinline). (b) Wind vectors for the 20-hour high-pass filtered component.

50

La mer 53, 2015

vertical wave length; it has been reported thatused in this study were NetCDF files provided

the vertical scale of internal lee waves excited byfrominteractions between deep flows and topography

Humansphere, Kyoto University. Part of thisare ~600 m (NIKURASHIN and FERRARI, 2010).

study was supported by JSPS KAKENHI Grant

Research

InstituteforSustainable

Number 26610151.
5.

Remarks
Vertical propagation of NIW was observed in

the abyssal Japan Sea, where a barotropic flow
generally prevails. It is feasible to use the detailed
flow structure revealed by moored-ADCP observation of high spatial and temporal resolution to
elucidate mixing processes in the deep oceaninterior. Although vertical shears during theobservation period were relatively stable, typically on the order of 10-3 s-1, seasonal andintermittent intensifications of near-inertial flows
have been reported in the abyssal Japan Sea(MORI et al., 2005). Strong vertical shear promoting oceanic mixing is possible during such
periods.
The horizontal wave number and propagation
angle of NIW were estimated from equation (2)which relates wave parameters m,

H, and. In particular, the propagation angle
sensitively on

withdepends, because the denominator of

equation (2) becomes very small for NIW.
However, since our observation period was only
about 46 hours, 2. 4 times of the local inertial
period, we could not estimate

precisely, posing

major limitation of this study. Precise estimationof

based on longer-period observation remains

as a problem to be solved in future.
Acknowledgments
We would like to thank the captain and crew of
the TR/V Nagasaki Maru and Mr. T. Mada forhelp in the observation field. Profs. T. MATSUNO, H.
-R. SHIN, and Dr. T. Endo are acknowledged for
useful discussions. The comments from two
anonymous reviewers were helpful for therevision of the manuscript. The GPV/MSM data

References
ALFORD, M.H., M.F. CRONIN and J.M. KLYMAK (2012):
Annual cycle and depth penetration of windgenerated near-inertial waves at ocean station
Papa in the Northeast Pacific. J. Phys. Oceanogr.,
42, 889-909.
BYUN, S. S., J. J. PARK, K. I. CHANG and R. W. SCHMITT(2010): Observation of near-inertial wave reflections within the thermostad layer of an anticyclonic mesoscale eddy. Geophys. Res. Lett., 37,
L01606, doi:10.1029/2009GL041601.
FU, L.L. (1981): Observations and models of internal
waves in the deep ocean. Rev. Geophys. Space
Phys., 19, 141-170.
FURUICHI, N., T. HIBIYA and Y. NIWA (2008): Modelpredicted distribution of wind-induced internal
wave energy in the world's ocean. J. Geophys. Res.,
113, C09034, doi: 10.1029/2008JC004768.
GAMO, T. and Y. HORIBE (1983): Abyssal circulation in
the Japan Sea. J. Oceanogr. Soc. Japan, 39, 220–230.
GARRETT, C. (2001): What is the “near-inertial” band
and why is it different from the rest of the internal
wave spectrum? J. Phys. Oceanogr., 31, 962-971.
GILL, A. E. (1982): Atmosphere-Ocean Dynamics.
Academic Press, Orlando, 662 pp.
HIBIYA, T., Y. NIWA, K. NAKAJIMA and N. SUGINOHARA(1996): Direct numerical simulation of the roll-off
range of internal wave shear spectra in the ocean.
J. Geophys. Res., 101 (C6), 14123-14129, doi:
10.1029/96JC01001.
IGETA, Y., Y. KUMAKI, Y. KITADE, T. SENJYU, H. YAMADA,
T. WATANABE, O. KATOH and M. MATSUYAMA(2009): Scattering of near-inertial internal waves
along the Japanese coast of the Japan Sea. J.
Geophys. Res., 114, C10002, doi: 10. 1029/2009JC
005305.
IGETA, Y., T. WATANABE, H. YAMADA, K. TAKAYAMA andO. KATOH (2011): Coastal currents caused by

Observation of near-inertial internal waves in the abyssal Japan Sea
superposition of coastal-trapped waves and nearinertial oscillations observed near the Noto
Peninsula, Japan. Cont. Shelf Res., 31, 1739-1749.
ISODA, Y. (1994): Warm eddy movements in theeastern Japan Sea. J. Oceanogr., 50, 1-15.
KANARI, S., M. KOGA, K. TAKEUCHI and M. TSUJI (1987):
Near-inertial internal waves in the area off Yoichi
coast of Hokkaido. Geophys. Bull. Hokkaido Univ.,
49, 369-379.
KIM, H. J., Y. G. PARK and K. KIM (2005): Generation
mechanism of near-inertial internal waves observed off the east coast of Korea. Cont. Shelf Res.,25, 1712-1719.
KIM, H.R., S. AHN and K. KIM (2001): Observations ofhighly nonlinear internal solitons generated bynear-inertial internal waves off the east coast of
Korea. Geophys. Res. Lett., 28(16), 3191-3194.
KUNZE, E. (1985): Near-inertial wave propagation ingeostrophic shear. J. Phys. Oceanogr., 15, 544-565.
LARGE, W.G. and G.B. CRAWFORD (1995): Observations
and simulations of upper-ocean response to wind
events during the Ocean Storms Experiment. J.
Phys. Oceanogr., 25, 2831-2852.
LIE, H.J. (1988): Near-inertial current oscillations off
the mid-east coast of Korea. Prog. Oceanogr., 21,
241-253.
MORI, K., T. MATSUNO and T. SENJYU (2005): Seasonal/
spatial variations of the near-inertial oscillations in
the deep water of the Japan Sea. J. Oceanogr., 61,
761-773.
NIKURASHIN, M. and R. FERRARI (2010): Radiation anddissipation of internal waves generated by geostrophic motions impinging on small-scale topography: theory. J. Phys. Oceanogr., 40, 1055-1074.
OKEI, N., J. OKUNO and T. SENJYU (2009): Kyucho
around the Noto Peninsula induced by the passage
of meteorological disturbances, the observations insummer 2003. Oceanogr. in Japan, 18, 57-69.
PARK, J. H. and D. R. WATTS (2005): Near-inertial
oscillations interacting with mesoscale circulationin the southwestern Japan/East Sea. Geophys.
Res. Lett., 32, L10611, doi: 10.1029/2005GL022936.
PARK, K.A., D.S. ULLMAN, K. KIM, J.Y. CHUNG and K.R.
KIM (2007): Spatial and temporal variability ofsatellite-observed subpolar front in the East/

51

Japan Sea. Deep-Sea Res. I, 54, 453-470.
SENJYU, T., T. ARAMAKI, S. OTOSAKA, O. TOGAWA M.
DANCHENKOV, E. KARASEV and Y. VOLKOV (2002):
Renewal of the bottom water after the winter2000-2001 may spin-up the thermohaline circulation in the Japan Sea. Geophys. Res. Lett., 29(7),doi: 10.1029/2001GL014093.
SENJYU, T., H.R. SHIN, J.H. YOON, Z. NAGANO, H.S. AN, S.K.
BYUN and C.K. LEE (2005): Deep flow field in theJapan/East Sea as deduced from direct current
measurements. Deep-Sea Res. II, 52, 1726-1741.
SENJYU, T., T. ARAMAKI, S.S. TANAKA, J. ZHANG, Y. ISODA,
Y. KUMAMOTO, S. HIBINO and T. NAKANO (2013):
Abyssal water mass exchange between the Japanand Yamato Basins in the Japan Sea. J. Geophys.
Res. Ocean, 118, 4878-4888, doi: 10.1002/jgrc.
20373.
SHCHERBINA, A.Y., L.D. TALLEY, E. FIRING and P. HACKER(2003): Near-surface frontal zone trapping anddeep upward propagation of internal wave energy
in the Japan/East Sea. J. Phys. Oceanogr., 33,
900-912.
TAKEMATSU, M., Z. NAGANO, A.G. OSTROVSKII, K. KIM and
Y. VOLKOV (1999): Direct measurements of deep
currents in the northern Japan Sea. J. Oceanogr.,
55, 207-216.
TANG, C. L. (1979): Inertial waves in the Gulf of St
Lawrence: a study of geostrophic adjustment.
Atmos.-Ocean, 17, 135-156.
TOOLE, J.M. and T.J. McDOUGALL (2001): Mixing andstirring in the ocean interior. In Ocean Circulation
and Climate, Siedler, G., J. Church and J. Gould(eds.), Academic Press, San Diego, p. 337-355.
WEBSTER, F. (1968): Observations of inertial period
motions in the deep sea. Rev. Geophys. Space
Phys., 6, 473-490.
WORTHINGTON, L. V. (1981): The water mass of theworld ocean: some results of a fine-scale census. In
Evolution of Physical Oceanography, Warren, B.A.
and C. Wunsch (eds.), M.I.T. Press, Cambridge, p.
42-69.
Received: April 7, 2015
Accepted: October 2, 2015

La mer 53 : 53-60, 2015
Société franco-japonaise dʼocéanographie, Tokyo

Temporal variation of microalgal chlorophyll a in surface ice
and the underlying Water in lagoon Notoro-ko, Hokkaido, Japan.
Yasuto NISHINO1), Tomoki SATOH2) and Akira TANIGUCHI3)

Abstract: Lagoon Notoro-ko is a large brackish lake on the Okhotsk Sea coast of Hokkaido. It iscompletely covered with sea ice during winter and hydrographic and biological conditions during
this season are unknown. Previous investigations done in warm seasons indicate that the lagoon
water is almost the same as the Okhotsk Sea water because there are few inflows from the land.
We conducted a winter investigation into the temporal changes of microalgal chlorophyll a in thesea ice and water column beneath it during the period from February 6 to March 18, 2008. Of thesurface PAR, 1% penetrated to 6–10 m depth in the water column beneath the ice, where
0.4–6.0 mg/m3 chlorophyll a was detected. Integrated chlorophyll a in 18 m ranged
8.7–119.1 mg/m2. In contrast, chlorophyll a levels in 20–31 cm thick ice ranged 2.5–11.6 mg/m2,
relatively less than in the water column. However, because chlorophyll a was largely concentrated
in the bottom-most part of the ice, it might be available to grazers in the underlying water. During
ice melting, a large proportion of the populations released from the ice likely sunk to the sea
bottom rather than remaining in the water column.
Keywords : ice algae, phytoplankton, chlorophyll a, Lagoon Notoro-ko

1. Introduction

lakes on the Okhotsk Sea coast of Hokkaido also

The Okhotsk Sea is a marginal subarctic sea infreeze every winter. However, few studies on thethe western North Pacific. It is bordered byrelationship between sea ice and biologicalSiberia Russia in the north and west and by

production have been conducted in the sea. One

Hokkaido, Japan, in the south. It is the southern-of the reasons for this is that the majority of themost ice-covered sea in the northern hemispheresea ice in the Okhotsk Sea is floe or drifting ice,during winter（WATANABE, 1963; PARKINSON andwhich makes it very difficult to follow its effect on. Many of the lagoons and brackish
GRATZ, 1983）

biological production over time. To avoid this1）Faculty of Bio-Industry Tokyo University ofAgriculture, 196 Yasaka, Abashiri, Hokkaido
099-2493, Japan
2）Hokkaido National Fisheries Research Institute,Fisheries Research Agency, 2-2 Nakanoshima,
Toyohira, Sapporo, Hokkaido 062-0922, Japan
3）Sanyo TechnoMarine, Inc., 1-3-17, NihombashiHoridomecho, Chuo-ku, Tokyo 103-0012, Japandifficulty, we focused on fast sea ice.
There are several lagoons and brackish lakes in
the coastal region of eastern Hokkaido, Japan thatare permanently connected to the Okhotsk Sea
and freeze on the surface in winter. Theselagoons and lakes are productive fishing grounds,
particularly for marine demersal resources.
Among them, Lagoon Notoro-ko is the second

54

La mer 53, 2015

largest and its water is exchanged with the
Okhotsk Sea water by tidal force. On the other
hand, there is little inflow from land drainage. As
a result, the physical and chemical properties ofthe lagoon water are quite similar to those of the
Okhotsk Sea（IMADA et al., 1995; NISHINO et al.,
. Because of this, the ice cover in Lagoon
2007）
Notoro-ko can be considered as a fast ice of the
Okhotsk Sea and a suitable stage to investigate
the Okhotsk Sea ice（KURATA and NISHIHAMA, 1987;.
WATANABE et al., 1991; ASAMI and IMADA, 2001）
The ice in Lagoon Notoro-ko starts to form inlate December, becomes fast enough for humanactivities between late January and late Marchand melts away by mid-April. We conducted aseries of investigations on the distribution of
microalgal chlorophyll a in both the ice（ice algae）
and the underlying water（phytoplankton）in
February and March 2008. This paper reports
temporal changes in the distributions of the ice
algae and the phytoplankton and discusses theecological role of the sea ice in the Okhotsk Sea.
2. Methods
Field surveys were conducted approximately
once a week or five times in total during theperiod from February 6 to March 18, 2008, when
on-ice activity was feasible, at a fixed station in
the deepest part of the Lagoon Notoro-ko. Its

Fig. 1 Station（solid circle）for serial observations
on microalgal chlorophyll a contents in ice coverand the underlying water column at the center ofthe deepest basin in Lagoon Notoro-ko onthe
Okhotsk Sea coast of Hokkaido, Japan, from February 6 to March 18, 2008. Depth contours are
given at 5 m intervals.

geographical position is 44°
03′03⼱N, 144°
09′45⼱E,

sensor into the underlying water column throughand the depth to the bottom is approximately 20

the hole left after ice core sampling（diameter: ca.

m（Fig. 1）. Ice cores were taken with an ice

10 cm）. PAR at different depths is expressed inauger of 7 cm in diameter and water samples.
relative values（%）to that above the ice（in air）

were taken at 1 m, 5 m, 10 m, 15 m and 18 m with

The ice cores were divided into five parts, i.e.

a Van Dorn bottle. Vertical temperature, salinity

upper, upper-middle, middle, middle-lower andand density（sigma-t）profiles were recorded

lower. The upper, middle and lower parts werewith a CTD（JFE Advantech, Model ASTD102）.

exactly 5 cm in length, while length of the upper-

Penetration of photosynthetically active radiation

middle and middle-lower parts differed depend-（PAR）into the water column beneath the ice

ing on the thickness of the ice on the day of

was measured with a quantum meter（JFEsurvey. Each of the ice cores was thawed andAdvantech, AL30-CMP）by susupending thechlorophyll a measured. Size-fractionated（> 10

Chlorophyll a of sea ice and water column

55

Table 1. Underwater PAR（photosynthetically active radiation）at five sampling depths in values relative tothose on the ice cover（%）during the ice-covered period from February 6 to March 18, 2008 in Lagoon
Notoro-ko. Sea ice thickness（cm）is also given for each sampling day.
Sampling dateFeb. 6

Feb. 18

Feb. 29

Mar. 10

Mar. 18（Ice thickness）

（20）

（29）

（30）

（31）

（21）

Depth（m）

2.60

1.50

1.70

3.10

6.00

5

0.75

0.42

0.53

0.98

1.15

10

0.30

0.17

0.23

0.40

0.37

18

0.17

0.10

0.11

0.25

0.25

~20

0.11

0.07

0.03

0.24

0.11

µm, 2–10 µm, < 2 µm）chlorophyll a concentrations were measured in the seawater samples andthawed ice by a serial filtration through polycarbonate filters of 10 µm and 2 µm in pore size
（Whatman）and a glass fiber filter（GF/F,. Chlorophyll a on the filters was
Whatman）
extracted in dimethylformamide and measured
with a fluorometer（Turner-Design, 10-AU）according to the WELSCHMEYER（1994）.
3. Results and Discussion
3.1 Hydrographic conditions beneath ice cover（Fig. 2, Table 1）
Temperatures in the water column beneaththe ice ranged from -2.3℃ to -1.0℃ and generally
increased with depth. On February 18, supercool
water below -1.8℃ had formed in the upper 5 mand, as a result, an inverse thermocline formed
around 5 m. Thereafter, temperature gradually
increased at every depth, particularly below
10 m, and a thermocline formed around 15 m.
Salinity was < 32.7 throughout the watercolumn during the survey period, except for
February 18, when very saline water appeared in.
the surface and bottom layers（maximum: 33.3）
On February 29, it was indicated that the saline
surface water has sunk and been diluted. Salinity
dropped to < 32.4 through the water column inMarch. Very low salinity water was detected at
the surface（minimum: 29.3）on March 18.

Fig. 2 Time courses in vertical section of temperature（a: ℃）, salinity（b）and density（c: sigma-T）in the water column observed during the icecovered period from February 6 to March 18,
2008, at the fixed station in Lagoon Notoro-ko on
the Okhotsk Sea coast of Hokkaido, Japan. The
bottom depth was about 20 m.

56

La mer 53, 2015

Sigma-t was over 26 in most cases, which waswater mass occupying Lagoon Notoro-ko during

higher than that in warm seasons, i.e. 21.5-26.1

winter is basically the coastal water affected by（NISHINO unpublished data）. The temporal andthe East Sakhalin Current and temporarily

vertical changes of sigma-t generally followed

modified by the formation and melting of the ice.

those of salinity. High sigma-t values, > 26.9, were

Further investigations on nutrient compositions

observed in both the surface and bottom layers

and plankton assemblages are necessary.

on February 18. The lowest density（23.5）was

Table 1 shows underwater PAR intensities inobserved on March 18 in the diluted surface

relative values（%）to that above the ice. Relative

water.

PAR at 5 m depth was 2. 6% on February 6; itA coastal divergence from the East Sakhalindecreased afterwards in February（1. 5-1. 7%）

Current reaches the coast of eastern Hokkaido in

and increased again to 6.0% in March. PARs at

autumn and winter（OHSHIMA et al., 2002; SHIMIZU

other depths varied in parallel with this. The 1%

and OHSHIMA, 2006）, which is characterized by

PAR depth, which is generally assumed to be thesalinities below 32（FUJII and SATOH, 1979;

compensation depth of phytoplankton photosyn-

TAKIZAWA, 1982）. Salinity at or below 32.4 in thethetic production, was 6. 5-10. 7 m during thecoastal water in winter indicates the presence ofentire period, indicating that positive production. The
the East Sakhalin Current（AOTA, 1979）

was continually performed at significant depths

present results revealed the intrusion of thisthrough the ice covered period. This is notwater mass（< 32. 4）into Lagoon Notoro-ko insurprising because the lagoon is located in thewinter. Within this water mass, high salinity

southern half of the northern hemisphere（44°03’water appeared separately in the surface and theN）. Recorded values of the ten-day average ofbottom layers in late February, forming an

daily solar irradiance during the same period

inverse pycnocline in the surface and a normal

were 5.3-7.1 MJ/m2 in January, 8.8-10.5 MJ/m2 in

pycnocline in the bottom layer. Such unusual

February and 11.9-12.5 MJ/m2 in March, which

stratification indicates that some unfrozen brine

were about 23-54% of the annual maximum

water had sunk rapidly to the bottom before

recorded in middle of May（23.1 MJ/m2）of the

February 18 and the exclusion of the brinesame year（JAPAN METEOROLOGICAL AGENCY, 2008）.

continued until February 29. We conclude that ice

KISHINO（1993）reported that relative PAR

is most actively formed in February in Lagoon

beneath 33 cm thick ice was about 0. 7% under

Notoro-ko. In March, the low salinity water

natural conditions and about 4% after theaffected by the East Sakhalin Current again filled

removal of snow that had accumulated on the ice

the entire water column, except for the surface

in Lagoon Saroma-ko, about 100 km north ofwater which was diluted by melting ice. It is

Lagoon Notoro-ko. Although this demonstrates

possible that the high salinity bottom waterthat light penetration through ice is largely

observed in February may have been the result

obstructed by snow accumulation, such heavyof a temporary intrusion of Okhotsk Sea

accumulation was not recorded on any occasion

Intermediate Cold Water, which is highly saline

in the present investigation in Lagoon Notoro-ko.

. If it had been
being 32.8-33.3（TAKIZAWA, 1982）

The reason for this difference between lagoons is

the case, it occurred within a very short period

not clear at present.

.
and was limited to a thin bottom layer（Fig. 2）
Therefore, it is a reasonable conclusion that theChlorophyll a of sea ice and water column

57

Fig. 3 Vertical section of total chlorophyll a over time（a）, large-sized chlorophyll a > 10 µm（b）, medium-sizedchlorophyll a 2–10 µm（c）and small-sized chlorophyll a < 2 µm（d）in 20–31 cm thick sea ice（upper）and theunderlying water column down to 18 m（lower）from February 6 to March 18, 2008. The bottom depth was
about 20 m.

3.2 Chlorophyll a（Fig. 3）

The sudden decrease in chlorophyll a in the ice

Chlorophyll a concentration in the ice wasfrom February 29 to March 10 is remarkable and2.2–8.4 µg/L in the upper part, 2.8–13.4 µg/L ininteresting. Because the ice was approximately

the middle part and 21.8–163.6 µg/L in the lower

the same thickness in this period, it is unlikely

part. This demonstrates that so-called ice algaethat the lower layer of the ice holding dense algae（microalgal communities within sea ice）can at-

had melted. It must be noted that chlorophyll a intain very high densities particularly in the lower

the middle part also dropped markedly from 13.4

part of the ice. Fig. 3 shows that their density

to 3.3 µg/L in the same period. One possible

gradually increased during the course of ice

explanation for this decrease is as follows: As

development until the end of February, butsolar radiation and air temperature increased

suddenly decreased when the ice started melting, the ice might start melting（data not shown）

in early March. Among the ice algae, the large

internally before the surface temperature of thesize class（> 10 µm）always predominated, while

underlying water increased to the melting

intermediate（2–10 µm）and small（< 2 µm）size

temperature of the sea ice（-1.8℃）. The internalclasses usually contributed less than 20%. The

melt probably progressed around brine pockets,

exclusive dominance of the large size class waswhich are characteristic of sea ice. The pockets

constant throughout the survey period. Similar

gradually expanded and the ice algae inside weretrends of vertical and temporal variations of thereleased into the underlying water. During this,ice algal chlorophyll a had been observed in a

the thickness of the ice might have remained

preliminary survey done in the preceding winter;unchanged.

while absolute concentration was apparently dif-

Released ice algae partly contributed to an in-ferent between deep central area（this station）

crease in phytoplankton in the underlying waterand shallow near-shore area, the trends werecolumn. As seen in Fig. 3, such a contribution toessentially the same in different areas. Similarity

phytoplankton increase was positive in the small-in concentration between several ice cores col-er size classes but less so in the large size class.

lected from the area of ca. 1 m3 had also been
confirmed.

The latter indicates that the large-sized ice algae,
probably in the form of colonies or aggregates,

58

La mer 53, 2015

Fig. 4 Temporal changes in chlorophyll a stocks in the ice cover（■）and the underlying water column（■）intotal amount（upper: mg/m2）and average concentration（lower: mg/m3）observed during the ice-covered
period from February 6 to March 18, 2008, in Lagoon Notoro-ko, Hokkaido, Japan.

sunk down to the sea bottom rapidly and weretions interact differently in different size classes.

hardly sampled with a Van Dorn bottle. If so, alarge proportion of the ice algae contributed tothe benthic rather than planktonic community. A
bloom of the larger phytoplankton occurred on

3.3 Integrated chlorophyll a in ice and watercolumn（Fig. 4）
The amount of integrated chlorophyll a

March 18, well after the major decrease of large-

through the ice cores was 2. 5 mg/m2 at begin-

sized ice algae and took place in subsurface layer

ning, increased steadily to a maximum of（5–10 m）instead of the surface layer underneaththe melting ice（Fig. 3b）. Since PAR at 10 m on

11.6 mg/m2 on February 29 and dropped to 1.7

and 2.7 mg/m2 on March 10 and 18, respectively.

, blooming in the
March 18 was 1.15%（Table 1）

During this period, since ice thickness was more

5–10 m layer was natural. It is interesting to noteor less constant at 20–31 cm（Fig. 3）, accumula-that the larger phytoplankton avoided the lowtion and loss of chlorophyll a should have occur-

salinity surface water underneath the melting ice

red in the bottom part of the ice. The sudden

but the smaller size classes did not. This demon-

decrease in chlorophyll a on March 10, when thestrates that ice algae and phytoplankton popula-

thickness of the ice was still increasing, albeit

Chlorophyll a of sea ice and water column

59

marginally, is interesting（Fig. 3）. This implies

in Lagoon Notoro-ko is not limited in this way.

that release of the ice algae into the underlying

The present results evidently show that, in thewater column is triggered by the widening of thewater column covered with 20–31 cm ice, the 1%

brine pockets inside the ice, not because of the

PAR depth（compensation depth）was as deep ascollapse of the sea ice, as discussed in the preced-. The phytoplankton chlor6.5–10.7 m（cf. Table 1）

ing chapter.

ophyll a concentration was well over 1.0 µg/L toIntegrated chlorophyll a through water column. This level
the depths throughout winter（Fig. 3）

to 20 m depth differed from that in the ice overof chlorophyll a is comparable to those in warm

time. Chlorophyll a continually increased in theseasons（KURATA and NISHIHAMA, 1987; NISHINO etwater column from 8.7 mg/m2 on February 6 to2al., 2014）. The brackish nature of the lagoon

43. 7 mg/m on March 10 and finally reachingwater might benefit this; the water column is119.1 mg/m

easily stratified and holds phytoplankton in the2

on March 18. Consequently, theratio of the ice algae to phytoplankton in total

shallower layers.

chlorophyll a was relatively high before March 10

Stocks of chlorophyll a within the ice（ice algae）

with a maximum of about 25% on February 29,

were also notably large. Integrated chlorophyll abut decreased sharply to about 2% in March. Nev-

was comparatively smaller than in the underlying

ertheless, the average chlorophyll a concentrationwater column but its concentration was very highin the ice was always higher than in the water（Fig. 4）
. A certain proportion of the ice algal

column even on March 18 when the phytoplank-

populations is continuously released into theton bloom occurred. Because it is generallywater. This might form an efficient forage site of

known that the density of dietary microalgae

filter feeders in the underlying water, because

positively affects herbivore feeding efficiency, thethey prefer dense food suspension to phytoplank-sea ice provides herbivores with efficient grazing

ton distributed over wide water column（PARSONS

areas, especially on its under surface exposed toand TAKAHASHI, 1973; TANIGUCH, 1975）. Since ma-

the water. Benthopelagic mysids and shrimps

jor part of the ice algae is concentrated into thewere occasionally observed with abundant cope-bottom-most part of the ice, their products are

pods in the surface layer at the present investiga-

partly available to grazers including benthopela-tion site（data not shown）.

gic organisms on the under-surface of the ice. We
also suggest that most of the large-sized ice algae

4. Conclusions

sink directly to the sea bottom in late February

The present study site, Lagoon Notoro-ko, is（Fig. 3）, which might be consumed by benthic

located in the southern half of the northern hemi-

grazers. Such contribution of the ice algae could

sphere. This makes the light conditions in the

be determined by collecting the sinking colonies

water column under ice cover essentially differ-with e.g. sediment traps in future survey.

ent to that in high arctic seas. In the high arctic,

In summary, sea ice is a unique ecological plat-because solar radiation in winter is generally low

form, where microalgae perform three primaryand largely reflected by snow and ice, under-

producer roles, i.e. produce nutrient rich products

water light conditions are very poor and thus

, allow grazers to feed on the products（pasture）

phytoplankton production is negligibly low. In（meadow）and transport products to the benthic

contrast, except on the occasional heavy snow.
community（feeder）

days, phytoplankton photosynthetic production

60

La mer 53, 2015

References
AOTA, M.（1979）: Oceanographic conditions in the
coastal area of southwestern Okhotsk Sea. Bull.
Coast. Oceanogr., 17, 1-11.
ASAMI, H. and K. IMADA（2001）: Ice algae andphytoplankton in the late ice-covered season in
Notoro Ko lagoon, Hokkaido. Polar Biosci., 14,
24-32.
FUJII, K. and Y. SATOH（1979）: Oceanographic structure and production in Japan Sea and costal
Okhotsk Sea. Bull. Jpn. Soc. Fish. Oceanogr., 34,
57-62.
IMADA, K., S. SAKAZAKI, T. KAWAJIRI and K. KOBAYASHI（1995）: Lake basin and saline environments
profiles of four brackish lakes in Abashiri, northern Hokkaido. Sci. Rep. Hokkaido Fish. Hatchery,49, 37-48.
: Global solar
JAPAN METEOROLOGICAL AGENCY（2008）
radiation and temperature in Abashiri in 2008, at
http: //www. data. jma. go. jp/obd/stats/etrn/, accessed 13 October 2015.
: Spectral light environment in/
KISHINO, M.（1993）
under sea ice in Lake Saroma. Bull. Plankton Soc.
Japan., 39, 161-165.
KURATA, M. and Y. NISHIHAMA（1987）: Seasonal changeof the hydrographic condition in Lake Notoro,
Hokkaido. J. Hokkaido Fish. Exp. Sta., 29, 17-24.
NISHINO, Y., T. SATOH, K. ASAKUMA, A. SHIOMOTO and A.
TANIGUCHI（2007）: Seasonal and Vertical Distribution of Phytoplankton and Nutrients in Lagoon
Notoroko on the coastal Okhotsk Sea. Proc. Application of a Closed Experimental System to Modeling of 14C Transfer in the Environment, 196-201.
NISHINO, Y., T. SATOH, A. SHIOMOTO and A. TANIGUCHI（2014）: Lower trophic levels of coastal marine
ecosystem in Lagoon Notoroko on the coastal
Okhotsk Sea --seasonal change of size fractionatedchlorophyll a and dissolved inorganic nitrogen--. J.
, 11-20.
Agric. Sci., Tokyo Univ. Agric. 59（1）OHSHIMA, K. I., M. WAKATSUCHI and Y. FUKAMACHI（2002）: Nearsurface circulation and tidal currentsof the Okhotsk Sea observed with satellite, 3195.
tracked drifters. J. Geophys. Res., 107（C11）
PARKINSON, C. L. and A. J. GRATZ（1983）: On theseasonal sea ice cover of the Sea of Okhotsk. J.

Geophys. Res., 88, 2793–2802.
PARSONS, T. R. and M. TAKAHASHI（1973）: Biological
Oceanographycal Processes, Pergamon Press, Oxford, New York, 186pp.
SHIMIZU, D. and K. I. OHSHIMA（2006）: A model simulation on the circulation in the Sea of Okhotsk andthe East Sakhalin Current. J. Geophys. Res., 107（C11）, 3195.
: Characteristics of the Soya
TAKIZAWA, T.（1982）
Warm Current in the Okhotsk Sea. J. Oceanogr.
Soc. Japan, 38, 281–292.
: Production Ecology of ZooTANIGUCHI, A.（1975）
plankton. In Marine plankton. MOTODA, S.（ed.）,
Tokai University Press. p. 117-235.
WATANABE, K.（1963）: On the reinforcement of theEast Sakhalin Current preceding to the sea ice
season off the coast of Hokkaido—Study on the sea. Oceanogr. Mag., 14,
ice in the Okhotsk Sea（IV）
117–130.
WATANABE, K., H. SATOH, Y. YAMAGUCHI, A. TANIMURA,
T. KONO, Y. INOUE and M. FUKUCHI（1991）: Ice algal
assemblages from lagoons Saroma-Ko, Notoro Ko
and Akkeshi-Ko in Hokkaido. Abstracts of The
Sixth International Symposium. The Okhotsk Sea
and Sea Ice. Monbetsu, 75-79.
WELSCHMEYER, M.A.（1994）: Fluorometric analysis ofchlorophyll a in the presence of chlorophyll b andpheopigments. Limnol. Oceanogr., 39（8）, 19851992.
Received: September 7, 2015
Accepted: November 7, 2015

La mer 53 : 61-71, 2015
Société franco-japonaise dʼocéanographie, Tokyo

Seasonal variations in the population structure and depth
distribution of Calanus sinicus in northern Kagoshima Bay
T. KOBARI1)＊, S. HOSOUCHI1), H. MORI2), H. OTA1), R. FUKUDA3) and M. UCHIYAMA3)

Abstract: We investigated seasonal variations of population structure and depth distribution of
Calanus sinicus in northern Kagoshima Bay. Animals were abundant during April to June whenchlorophyll a concentrations were high. Young copepodites or adults appeared over the seasons,however, copepodite stage 5 dominated when the population abundance was the lowest during
August 2009 and July 2010. We found little indication of seasonal vertical migration since alldevelopmental stages occurred above 50 m and below 100 m throughout the year. RNA:DNA
ratios revealed no significant decline throughout the year. These results suggest that Calanus
sinicus reproduces throughout the year and does not experience a deep-water dormancy period innorthern Kagoshima Bay.
Keywords : Calanus sinicus, population structure, depth distribution, nucleic acids

Introduction

from lower trophic levels of both the classical andCalanoid copepods are among the most diverse

microbial food webs because they consume phy-groups of crustacean zooplankton（more than

toplankton, heterotrophic microzooplankton, and, contribu2000 species; RAZOULS et al., 2005-2013）

sinking detrital particles（DAGG, 1993; GIFFORD,

ting significantly to marine biomass（VERITY and

1993; KOBARI et al., 2003）. They represent a major

SMETACEK, 1996）with greater than half of thefood resource for epi- and mesopelagic fishes

global abundance of zooplankton（LONGHURST,（BRODEUR et al., 1999; MOKU et al., 2000; YAMAMURA. These copepods integrate carbon flows
1985）

et al., 2002）, marine mammals（KAWAMURA, 1982）,
and seabirds（RUSSELL et al., 1999）. Thus, an1）Aquatic Sciences, Faculty of Fisheries, Kagoshima
University, Shimoarata 4-50-20, Kagoshima,890-0056, Japan
2）Aquatic Sciences, Graduate School of Fisheries,
Kagoshima University, Shimoarata 4-50-20,
Kagoshima, 890-0056, Japan
3）T/S Kagoshima Maru, Faculty of Fisheries,
Kagoshima University, Shimoarata 4-50-20,
Kagoshima, 890-0056, Japan＊Corresponding author:
Phone: +81-99-286-4140, Fax: +81-99-286-4015
E-mail address: kobari@fish.kagoshima-u.ac.jp

understanding of trophodynamics in marine
ecosystems demands careful study of the population dynamics of calanoid copepods.
Calanus sinicus Brodsky（1965）is widely distributed around coastal areas in East Asia（e.g.,
HULSEMANN, 1994）where it contributes the biomass of zooplankton communities（UYE and. However, the life
SHIMIZU, 1997; UYE et al., 1999）
history of Calanus sinicus is quite variable. For
example, reproduction occurs throughout theyear in the Inland Sea of Japan（HUANG et al., 1992,

62

La mer 53, 2015

1993a, b）, whereas stage 5 copepodites（C5）arebility and deep water column, and is character-found in abundance at depth in Sagami Bay

ized by year-round reproduction with no dormant（NONOMURA et al., 2008）and the Yellow Sea（PU etstock. We tested our hypothesis by monitoring, indicating a dormant life historyal., 2004a, b）

seasonal changes in population structure andphase. In the Yellow Sea, they produce dormant

depth distribution with monthly sampling. In ad-

stock residing at depth during the food-scarcedition, we measured nucleic acids contents of thesummer and increase their abundance during theC5s in order to evaluate the potential for dorman-

food-rich seasons（PU et al., 2004a, b; ZHANG et al.

cy similar to other subarctic Pacific copepod

2007）. UYE（2000）reviewed that this species.
groups（KOBARI et al., 2013）

prospered in the shelf ecosystem with not only
suitable ambient temperature and food supply for

Materials and Methods

reproduction and development but also enough

Oceanographic observations and zooplankton

depth for diel vertical migration and egg hatching

sampling

before sink to bottom. However, there is little

Oceanographic observations and zooplankton

information on the life cycle prospering in thesampling in Kagoshima Bay were carried out on aregion with suitable temperature, food availabil-monthly basis, between April 2009 to December

ity and depth.

2010 at S16（31°39.9́N, 130°41.9́E: 140-m deep;

Kagoshima Bay is a large semi-enclosed embay-

Fig. 1）. All sampling was carried out during

ment located at the southernmost part of Kyushu,

research cruises of the T/S Nansei-Maru. Tem-Japan. This embayment is characterized by deep

perature and salinity profiles down to 135 m were（deeper than 200 m）bathymetry. The deep andcarried out with CTD system（Seabird SBE-9）.

semi-enclosed nature of the embayment in the

Water samples for chlorophyll a and dissolved

northern area promotes deep-water hypoxia dur-oxygen measurements were collected from 8

ing autumn to winter period. Although we know

depths（10, 20, 30, 50, 75, 100, 125 and 135 m）

that C. sinicus occurs in the northern area ofwith a CTD-CMS system and from the sea sur-Kagoshima Bay（NOZAWA and SAISYO, 1980）,

face with a plastic bucket. These samples were

there is little knowledge of seasonal variations infiltered through a Whatman GF/F filter（0.7-µm

their population structure and depth distribution.

nominal pore size）under vacuum pressure

We expect the specific life cycle with continuous<20kPa. Chlorophyll pigments were immediately

reproduction and without dormancy in the north-extracted from material retained on filter papers

ern area of Kagoshima Bay due to 1) the suffi-

by direct immersion into N, N-dimethylforma-

cient depth for vertical migration and egg hatch-mide（DMF）at –5˚C in darkness for more than 24

ing, 2) the limited water exchange in the semi-. Chlorophyll ahours（SUZUKI and ISHIMARU, 1990）

enclosed embayment and 3) the suitable temper-

concentration was measured with a fluorometer

atures and food supply for growth and egg pro-（Turner Designs Co., TD-700）by the non-acidifi-.
duction（KOBARI et al. 2002, 2009）
The objective of this study was to clarify ayear-round reproduction and dormant stock of C.

.
ed fluorometric method（WELSCHMEYER, 1994）
Dissolved oxygen was determined by the Winkler titration method.

sinicus in the northern area of Kagoshima Bay.
Our hypothesis is that the population’s life cycle isadapted to the high temperature, high food availa-

Zooplankton collections and identification
Zooplankton samples for enumeration were col-

Seasonal variations in Calanus sinicus

63

Fig. 1. Location of oceanographic observations and zooplankton sampling in northern area ofKagoshima Bay（S16: 31°
40.2’N, 130°41.6’E）.

lected with a Vertical Multiple Plankton Sampler

tified to species and developmental stage under a（0.25-mdissecting microscope. C. sinicus C5s picked for2mouth square, 0.1-mm mesh size;

TERAZAKI and TOMATSU, 1997）hauled at 1 m sec-1

biochemical analyses were placed in 2 mL vials,

during the day time（09:00-11:00）for each cruise.

stored at –80℃, and transported back to land for

The following discrete depth intervals were sam-laboratory analyses of nucleic acids contents.

pled on the upcast: 0–50, 50–100 and 100–135 m.
Subsamples for enumeration were preserved in a

Nucleic acids analyses

5% borax-buffered formaldehyde seawater solu-

We measured RNA and DNA with the micro-tion. Individual C. sinicus were identified by stage

plate fluorescent assay（MFA）developed byfor copepodites（C1-C5）and by sex（i.e., male or

WAGNER et al.（1998）. The MFA assay is a modifi-

female）for adults（C6）. All animals were exam-

cation of the sequential fluorometric method of

ined under a stereo dissecting microscope（Nikon, in which DNA and RNA in a
BENTLE et al.（1981）

SMZ1200）.

single sample are determined sequentially by the

Fresh zooplankton samples for biochemical

addition of DNase and RNase using Ethidium

analyses were collected with vertical net hauls

Bromide as fluorescent dye（see CALDARONE et al.,(0.5 m sec-1）from near bottom to sea surface

2006 for details）. WAGNER et al.（1998）modified

using a modified North Pacific Standard net

the sequential fluorometric method to the MFA（MOTODA, 1957: diameter 45 cm, mesh sizewith 96-well microtiter plates by adopting a.
0.335 mm）equipped with a large cod end（2L）sarcosyl extraction technique and eliminating theOn deck, individual specimens were quickly iden-

DNase step, thus allowing application of the assay

64

La mer 53, 2015

to small samples（single copepods）without ex-

tions（µg mL-1）were computed from the second

tended working time.

scan and the standard curve of DNA versus

Each specimen was thawed and then homogenized by vigorous shaking with 5 zirconia beads influorescence established from the second scan
（RNase treated）of the same plate.

200 µL of a 1% sarcosyl extraction buffer. Samples were shaken for 5 minutes at room tempera-

Results

ture on a vortex mixer equipped with a multiple-

Environmental variables

vial head. Following the initial homogenization,

Sea surface temperature ranged from 16.3 tosamples were then diluted with Tris buffer to. The thermocline and halocline
29. 0℃（Fig. 2）

reduce the sarcosyl concentration to 0. 1%, andwere developed above 30 m during May to Au-

then shaken for an additional 10 minutes. Finally,

gust 2009 and during May to October 2010. Sur-

sampled were centrifuged（15000 g）for 10 min at

face waters during the summer of 2010 were

4℃ to separate insoluble copepod remains.

much less saline than for the same period in 2009.

In each run, 75 µL aliquots of sample superna-tant and 8 replicates from 0. 01 to 0. 5 µg mL-1

Over the course of the study period, seasonalvariations in temperature（16.1 to 18.3℃）below

DNA（calf-thymus, Sigma-Aldrich D4522）andfrom 0.02 to 3 µg mL-1 RNA（bakers-yeast,
Sigma-Aldrich R7125）were transferred to 96. Zero concentrations ofwell microplates（Nunc）
the standard solutions were also treated as reagent blanks（containing all chemicals but no co. Here, we used RiboGreen
pepod homogenate）（Invitrogen R11491）as a fluorescent dye insteadof Ethidium Bromide（used by WAGNER et al. 1998）
because of its greater nucleic acid sensitivity andefficacy（GOROKHOWA and KYLE, 2002）. We added
100 µL of 0.2% RiboGreen to each well, and theplates were then kept at room temperature for 5
minutes. The fluorescence of RiboGreen was thenscanned using a microplate reader（Perkin-Elmer,
ARVO MX1420）with 485 nm（excitation）and
535 nm emission) filters (First scan）. The RNase
solution（10 µL）was then added to each well.
The microplate was kept at room temperature
for another 20 minutes and RiboGreen fluores. The concencence was scanned（Second scan）

trations of RNA（µg mL-1）were calculated as thedifferences between first (DNA + RNA) and second（DNA）scans, and the standard curve ofRNA versus the fluorescence established fromthe first scan of the same plate. DNA concentra-

Fig. 2. Seasonal changes in vertical profiles of temperature（WT: ℃）, salinity（SAL: PSU）
, dissolved
oxygen（DO: mL L-1）and phytoplankton biomass（CHL: mg chlorophyll a m-3）at S16 in Kagoshima
Bay.

Seasonal variations in Calanus sinicus

65

Fig. 3. Seasonal changes in abundance（individuals m-2）and stage composition（%）of Calanus sinicus in thewater column from 135 m to sea surface at S16 in Kagoshima Bay. ND: No data.

100 m were less pronounced than variation of

50 m was high. C. sinicus C5s were typically thesalinity（33.9 to 34.1PSU）in the same depths. The

most abundant stage and were present through-dissolved oxygen concentrations above 50 m

out the study period. The population was com--1during the entire

posed entirely of C5s in August 2009 and July

study period. However, the dissolved oxygen2010 when the water column abundance of C.

were greater than 3.0 mL L

concentration below 100 m gradually declined

sinicus was the lowest（< 10 individuals m-2）.

after July 2009 and 2010 and reached to 1.1 mLYoung copepodites from C1 to C4 composed less-1

near the base of the water column in Decem-

than 30% of the population throughout the studyber 2009. Chlorophyll a concentrations wereperiod, except in April 2010（~50% of the total

greater than 5 mg m above 30 m during April toabundance）. Adult males and females were sam-L

-3

July in both years, but were 0. 5 to 1. 0 mg m-3
throughout the water column during December

pled during the most months, however, their seasonal pattern was not clear.

2009 to January 2010.
Depth distribution
We generally measured a high abundance of C.

Population structure
Peak abundance values for C. sinicus in thesinicus both above 50 m and below 100 m, except-

water column were measured in June 2009（216ed for November 2010 when the relative abun-

individuals m-2）
, April 2010（99 individuals m-2）
-2

dance was the greatest in the 50–100 m layer

and in November 2010（70 individuals m ）(Fig. 4). Over the course the year, C. sinicus was（Fig. 3）, when phytoplankton biomass above

abundant above 50 m during June to July and66

La mer 53, 2015

Fig. 4. Seasonal changes in relative depth distributions of Calanus sinicus developmental stages at S16 in
Kagoshima Bay. C1-C4: Copepodite stage 1 to 4. C5: Copepodite stage 5. C6: Copepodite stage 6（adult maleand female）. Note that some months are missing due to no sampling.

below 100 m in December but seasonal migration
was not apparent for the population. Moreover,
we noted no clear seasonal pattern when we
considered each developmental stage separately.
Young copepodites（C1 to C4）appeared abundantly in the layers above 50 m as well as below
100 m. Adults and C5s were abundant both above
50 m and/or below 100 m, except for November
2010 when they appeared abundantly in the
50–100 m layer.
Nucleic acids ratio
Individual DNA and RNA contents both decreased during August to October and then increased from November to December（Fig. 5）.
The RNA:DNA ratio was relatively stable during
the summer with values increasing toward December.
Discussion
While C. sinicus reproduction takes placethroughout the year in the Inland Sea of Japan,
the population follows a clear seasonal patternFig. 5. Seasonal changes in individual RNA and DNA
content（µg individual-1）and RNA:DNA ratios ofcopepodite stage 5 for Calanus sinicus at S16 in
Kagoshima Bay. Error bars represent ±1SE.

with high abundance during June to August andlow during September to March（HUANG et al.,
1992, 1993a, b）. Studies by Huang et al.（HUANG etperatures and food availability were suitable.

al., 1992, 1993a, b）found no evidence of a dor-

However, UYE（2000）has pointed out that C.

mant stock in the Inland Sea of Japan and con-sinicus prospers in shelf waters with enoughcluded that the population was able to produce

depth to perform full-scale vertical migration andthree generations a year because ambient tem-to avoid embedding at bottom before egg hatch-

Seasonal variations in Calanus sinicus

67

ing. On the other hand, a different life history was

bottom layers. These results suggest that C. sini-found for the Sagami Bay（NONOMURA et al., 2008）

cus conducts a year-round reproduction and does

and Yellow Sea（PU et al., 2004a, b; ZHANG et al.,not produce a dormant stock in the northern area2007）populations. While all developmental stagesof Kagoshima Bay. However, the timing of great-

were abundant above 100 m during May in

est abundance was earlier in northern area ofSagami Bay, C5s were found in the layers below

Kagoshima Bay（April to June）compared to that. Such a deep ap200 m（NONOMURA et al., 2008）of the Inland Sea of Japan（June to August）and

pearance of C5 was also evident for the C. sinicus

the regional variations may be due to differences

population in Yellow Sea（PU et al., 2004a, b;

in seasonal temperature and phytoplankton bio-ZHANG et al., 2007）. While all development stages

mass patterns.

including nauplii occurred in the water column

Laboratory studies on the growth and develop-

during August, C5s were concentrated at depth

ment of the congeneric species, Calanus pacificus

in the central part of Yellow Sea, indicating a（VIDAL, 1980a, b, c, d）, demonstrated that growthdormant stock. These latter studies suggest thatrate varied with temperature only under food-the Yellow Sea population of C. sinicus produces

saturated conditions. Similar interactive effects ofdormant stock during the summer when food

food availability and temperature have not been

availability is low and temperatures are highdemonstrated for C. sinicus growth and develop-

because their reproductive and development

ment rates. However, egg production rates havetimings fit the more favorable seasons（PU et al.,been demonstrated to increase logistically with

2004a, b; ZHANG et al., 2007）. These findings

phytoplankton biomass（UYE, 2000）while bothindicate that a variety of the life histories for C.

growth and development rates appear to besinicus is characterized by presence or absence of. Sea surface
temperature-dependent（UYE, 1988）

dormancy. Also, they seem to result from thetemperatures greater than 20℃ were evident

combined effects of food availability, thermal

during July in the Inland Sea of Japan（HUANG etregime, and deep bathymetry.

al., 1993a）and from May through December inPopulation abundance was high during April tothe northern area of Kagoshima Bay. High phyto-

June and low during July to August in theplankton concentrations were measured during

northern area of Kagoshima Bay. The seasonal

August and September in the Inland Sea of Japanchanges in abundance corresponded to those in（>5 mg m-3: HUANG et al., 1993a）and during May

chlorophyll a concentrations in the surface layer.

and June in the present study（> 10 mg m-3）.

A similar seasonal pattern was observed for theThus, it is appears that C. sinicus abundance

C. sinicus population in the Kii Channel of theincreases during the spring when thermal and. YoungInland Sea of Japan（HUANG et al., 1993a）food（i.e., phytoplankton biomass）conditions arecopepodites and adults were present during most

optimal for development and growth. This opti-of the study period and year-round reproduction

mal period occurs earlier in the northern area of

was also evident for the populations in the Inland

Kagoshima Bay relative to the Inland Sea of

Sea of Japan and the neighboring waters. In theJapan.

present study, seasonal migration was not clear

In the northern area of Kagoshima Bay, year-

for all development stages. While only C5 wasto-year variations were found for the environ-found in summer when the population abundance

mental conditions such as ambient temperature,

was the lowest, they appeared in both surface andsalinity and chlorophyll a from spring to summer.

68

La mer 53, 2015

As seen in less abundance for C. sinicus under

Kagoshima Bay. On the other hand, copepod

the low food availability in 2010, environmental

mortality increases with high thermal regimes

conditions during spring to summer are likely

since predation activity is enhanced（HUNTLEY

important for their life history strategy. However,and LOPEZ, 1992; HIRST and KIØRBOE, 2002）. The

even if they increased their abundance during

naupliiar and young copepodite stages of C. si-

spring to early summer like in 2009, the popula-nicus are known to reside in surface layers

tion abundance was lowest during summer whenthroughout the day（UYE et al., 1990; HUANG et al.

the population was composed entirely of C5s. In

1992, 1993b）. UYE（2000）pointed out that the C5

the Yellow Sea and Sagami Bay, C5s found in

and adult stages can, however, avoid visual pred-

deep layers are considered to be dormant（PU et

ators in the shelf waters where they are able toal., 2004a, b; ZHANG et al., 2007, NONOMURA et al.,carry out a full-scale diel vertical migration. The

2008）. In the present study, however, we find nowater column depth at our study site was 140 m,

evidence for dormancy in the northern area of

deeper than Kii Channel where the full-scale dielKagoshima Bay. For marine calanoid copepods,.
vertical migration has been observed（UYE, 2000）

dormancy has been identified by an empty and

Taking into account for the predominance of C5s

reduced gut（MILLER et al. 1984）or by the shapeeven under the cold thermal regime without the.
and/or structure of diapause eggs（BAN, 1997）, we suggrowth inhibition（i.e., winter to spring）

More recently, dormancy for copepods has also

gest that the predominance of C5s occurs（espe-

been identified biochemically by low aminoacyl-

cially in summer）as a result of high predationtRNA synthetase activities（YEBRA et al., 2006）or

mortality on early life stages. However, how do

low RNA:DNA ratios（KOBARI et al., 2013）. We didthey sustain their population with quite low abun-

not measure a significant decline in RNA: DNA

dance of the early life stages even in the year-

ratios for our study population. Based on theround reproduction and equiproportional devel-

equation developed by Kobari et al.（KOBARI et al.,? Indeed, the abundances of
opment（UYE, 1998）, the RNA: DNA ratios measured for C.
2013）

C1 to C4 were lower than those in the previous

sinicus were much higher than ratios measured

studies（UYE et al., 1990; HUANG et al. 1992, 1993b）.

for “active” copepods（1.0 to 1.6）
. These findings

Based on the results in the Yellow Sea（PU et al.,suggest that no dormant stock is formed for the

2004b）, C. sinicus exhibited different life history

C. sinicus population in the northern area ofstrategies to conduct summer dormancy at depth

Kagoshima Bay. Why then is the populationin the deepest area and to reproduce throughout

abundance low and composed of C5s during thethe year in the neighboring shallow area. Since

summer in the northern area of Kagoshima Bay?

there are basin areas deeper than 200 m in

Summer phytoplankton biomass never dropped

northern and southern Kagoshima Bay, C. sinicus

below 1 mg chlorophyll a m , indicating thatmight be sustained by recruitment of dormant

clutch size and spawning frequency were prob-

stock forming in the basin areas.

-3. It is possible that
ably food-saturated（UYE, 2000）

UYE（2000）pointed out that shelf waters might

hatching and development failures（i.e., embry-

provide a suitable habitat for C. sinicus due to theonic and naupliar malformations）were enhanced

ideal temperature, food supply and depth. Thesewith high summer surface temperatures（>25℃）

conditions of a sufficiently deep water column, the, resulting inas suggested by ZHANG et al.（2007）high thermal regime, and suitably high food sup-elevated mortality for early life stages inply appear to be met for the C. sinicus population

Seasonal variations in Calanus sinicus
in the northern area of Kagoshima Bay. The
importance of both ambient temperature andfood supply in copepod life cycles has been wellstudied（HUANG et al., 1993a; PU et al., 2004a, b;. Our study also emphasizes
ZHANG et al., 2007）
that water column depth plays an important rolein calanoid copepod life cycles because of thepotential limits imposed vertical migrants. It has
been hypothesized that coastal populations of C.
sinicus are supplied by estuarine circulationtransporting populations flourishing in shelfwaters（UYE, 2000）. However, such circulation
was limited in the northern area of Kagoshima
Bay due to the presence of a narrow channel（TAKAHASHI, 1977）. We suggest that C. sinicus
can complete their life cycle in the northern areaof Kagoshima Bay where food availability anddepth are suitable, even in the high thermal
regime.
Acknowledgement
We thank Dr. Akash Sastri for English corrections and valuable comments on manuscript draft
and crews of T/S “Nansei-Maru” for help withoceanic observations and plankton samplings. A
part of the present study was supported by
grants from the Japan Society for the Promotionof Science（21710012, 25340011）, Ministry of Education, Cultures, Sports, Science and Technology
Japan（SKED: The Study of Kuroshio Ecosystem
Dynamics

forSustainable

Fisheries） and

Kagoshima University.

References
BAN, S.（1997）. Dormancy in Copepoda. Oceanogr.
Japan, 7, 21-30.
BENTLE, L. A., S. DUTTA, J. METCOFF（1981）. The
sequential enzymatic determination of DNA andRNA. Anal. Biochem., 116, 5–16.
. Rapid and sensitive method
BRADFORD, M. M.（1976）69

for the quantitation of microgram quantities ofprotein utilizing the principle of protein-dye binding. Anal. Biochem., 72, 248–254.
CALDARONE E. M., C. M. CLEMMENSEN, E. BERDALET, T. J.
MILLER, A. FOLKVORD, G. J. HOLT, M. P. OLIVAR and
I. M. SUTHERS（2006）Intercalibration of four spectrofluorometric protocols or measuring RNA/DNA ratios in larval and juvenile fish. Limnol.
Oceanogr. Methods, 4, 153-163.
HIRST A. G. and T. KIØRBOE（2002）. Mortality of marine
planktonic copepods: global rates and patterns.
Mar. Ecol. Prog. Ser., 230, 195-209.
HUANG, C., S. UYE and T. ONBE（1993a）. Geographic
distribution, seasonal life cycle, biomass and production of a planktonic copepod Calanus sinicus in
the Inland Sea of Japan and its neighboring Pacific
Ocean. J. Plankton Res., 15, 1229-1246.
. Ontogenetic diel
HUANG, C., S. UYE and T. ONBE（1992）
vertical migration of the planktonic copepod Calanus sinicus in the Inland Sea of Japan. II. Late falland early spring. Mar. Biol., 123: 391–400.
HUANG, C., S. UYE and T. ONBE（1993b）. Ontogenetic
diel vertical migration of the planktonic copepod
Calanus sinicus in the Inland Sea of Japan. II. Earlysummer and overall seasonal pattern. Mar. Biol.,
117: 289–299.
HULSEMANN, K.（1994）. Calanus sinicus Brodsky andC. jashnovi, nom. nov.（Copepoda: Calanoida）of
the north-west Pacific Ocean: a comparison, with
notes on the integumental pore pattern in Calanus
s. str. Invertebrate Taxonomy, 8, 1461-1482.
. TemperaHUNTLEY, M. E. and M. D. G. LOPEZ（1992）
ture-dependent production of marine copepods: a
global synthesis. Ame. Nat., 140, 201-242.
.
KOBARI, T., T. ICHIKAWA and A. HABANO（2002）
Seasonal variations in phyto- and zooplankton
biomass in Kagoshima Bay. Mem. Fac. Fish.,Kagoshima Univ., 51, 19-25.
KOBARI, T., Y. KOBARI, T. ICHIKAWA, Y. KUGITA,
T. YOSHIDA, T. FUJII, S. FURUHASHI, T. YAMAMOTO,. Seasonal dyA. HABANO and R. FUKUDA（2009）
namics of microbial plankton community in
Kagoshima Bay. Aquabiol., 31, 37-44.（in Japanesewith English abstract）. Nucleic
KOBARI, T., H. MORI and H. TOKUSHIGE（2013）

70

La mer 53, 2015

acids and protein content in ontogenetically migrating copepods in the Oyashio region as influenced by development stage and depth distribution. J. Plankton Res., 35, 97-104.
KOBARI, T., A. SHINADA and A. TSUDA（2003）. Functional roles of interzonal migrating mesozooplankton in the western subarctic Pacific. Prog. Oceanogr., 57, 279-298.
KOBARI, T., D. K. STEINBERG, A. UEDA, A. TSUDA, M. K.
SILVER and M. KITAMURA（2008）. Impacts of
ontogenetically migrating copepods on downward
carbon flux in the western subarctic Pacific Ocean.
Deep-Sea Res. l, 55, 1648-1660.
. Relationship between diverLONGHURST, A. R.（1985）
sity and the vertical structure of the upper ocean.
Deep-Sea Res. 32, 12A, 1535-1570.
MILLER , C. B., B. W. FROST, H. P. BATCHLDER, M. J.
. Life histories of
CLEMONS and R. E. CONWAY（1984）
large, grazing copepods in a subarctic ocean gyre:
Neocalanus plumchrus, Neocalanus cristatus, andEucalanus bungii in the northeast Pacific. Prog.
Oceanogr., 13, 201-243.
MOTODA, S.（1957）. North Pacific standard plankton
net. Inform. Bull. Planktology Japan, 4, 13-15.
.
NONOMURA, T., J. R. MACHIDA and S. NISHIDA（2008）
Stage-V copepodites of Calanus sinicus and Calanus jashnovi（Copepoda: Calanoida）in mesopelagic zone of Sagami Bay as identified with genetic
markers, with special reference to their vertical
distribution. Prog. Oceanogr., 77, 45-55.
. Plankton in
NOZAWA, K. and T. SAISYO（1980）
Kagoshima Bay. Kaiyo Kagaku Monthly, 12,654-672（in Japanese）.
PU, X. M., S. SUN, B. YANG, P. JI, Y. S. ZHANG and. The combined effects of temF. ZHANG（2004a）perature and food supply on Calanus sinicus in thesouthern Yellow Sea in summer. J. Plankton Res.,26, 1049-1057.
PU, X. M., S. SUN, B. YANG, Y. S. ZHANG and F. ZHANG（2004b）. Life history strategies of Calanus sinicus
in the southern Yellow Sea in summer. J. PlanktonRes., 26, 1059-1068.
RAZOULS, C., F. BOVÉE, J. KOUWENBERG and
N. DESREUMAUX（2005-2013）. Diversity and geographic distribution of marine planktonic cope-

pods. Available at: http://copepodes.obs-banyuls.
fr/en（accessed on 14 September 2013）
SUZUKI, R. and T. ISHIMARU（1990）. An improved
method for the determination of phytoplankton
chlorophyll using N, N-dimethylformamide.
J. Oceanogr. Soc. Japan, 46, 190–194.
TAKAHASHI, A.（1977）. Hydrography in Kagoshima
Bay. Bull. Coast. Oceanogr., 14, 19-24.
. A vertical mulTERAZAKI, M. and C. TOMATSU（1997）
tiple opening and closing plankton sampler. J. Adv.
Mar. Sci. Tech. Soc., 3, 127–132.
. Ontogenetic diel
UYE, S., C. HUANG and T. ONBE（1990）
vertical migration of the planktonic copepod Calanus sinicus in the Inland Sea of Japan. Mar. Biol.,
104: 389–396.
. Temperature-dependent developUYE, S.（1988）
ment and growth of Calanus sinicus（Copepoda:
Calanoida）in the laboratory. Hydrobiol., 167/168,
285–293.
. Why does Calanus sinicus prosper in
UYE, S.（2000）
the shelf ecosystem of the Northwest Pacific
Ocean? ICES J. Mar. Sci., 57, 1850–1855.
UYE, S., N. IWAMOTO, T. UEDA, H. TAMAKI and
K. NAKAHIRA（1999）. Geographical variations in
the trophic structure of the plankton community
along a eutrophic–mesotrophic–oligotrophic transect. Fish. Oceanogr., 8, 227–237.
UYE, S. and T. SHIMAZU（1997）. Geographical andseasonal variations in abundance, biomass andestimated production rates of meso- and macrozooplankton in the Inland Sea of Japan. J. Oceanogr., 53, 529–538.
VERITY, P. G. and V. SMETACEK（1996）. Organism life
cycles, predation, and the structure of marine
pelagic ecosystem. Mar. Ecol. Prog. Ser., 130,277-293.
VIDAL, J.（1980a）. Physioecology of zooplankton. I.
Effects of phytoplankton concentration, temperature, and body size on the growth rate of Calanus
pacificus and Pseudocalanus sp. Mar. Biol., 56,
111-134.
VIDAL, J.（1980b）. Physioecology of zooplankton. II.
Effects of phytoplankton concentration, temperature, and body size on the development and molting rates of Calanus pacificus and Pseudocalanus

Seasonal variations in Calanus sinicus
sp. Mar. Biol., 56, 135-146.
VIDAL, J.（1980c）. Physioecology of zooplankton. III.
Effects of phytoplankton concentration, temperature, and body size on the metabolic rate of Calanus pacificus. Mar. Biol., 56, 195-202.
VIDAL, J.（1980d）. Physioecology of zooplankton. IV.
Effects of phytoplankton concentration, temperature, and body size on the net production efficiency of Calanus pacificus. Mar. Biol., 56, 203-211.
WAGNER, M. M., E. G. DURBIN and L. J. BUCKLEY（1998）.
RNA:DNA ratios as indicators of nutritional condition in the copepod Calanus finmarchicus. Mar.
Ecol. Prog. Ser., 162, 173-181.
. Fluorometric analysis of
WELSCHMEYER, N. A.（1994）
chlorophyll a in the presence of chlorophyll b andphaeopigments. Limnol. Oceanogr., 39, 1985-1992.
YEBRA, L., A. G. HIRST and S. HERNÁNDEZ-LEÓN（2006）
Assessment of Calanus finmarchicus growth anddormancy using the aminoacyl-tRNA synthetases
method. J. Plankton Res., 28, 1191-1198.
ZHANG G. T., S. SUN and B. YANG（2007）. Summer
reproduction of the planktonic copepod Calanus
sinicus in the Yellow Sea: influences of highsurface temperature and cold bottom water.
J. Plankton Res., 29, 179–186.
Received: September 7, 2015
Accepted: November 2, 201571

La mer 53 : 75-86, 2015
Société franco-japonaise dʼocéanographie, Tokyo学会

1．第 16 回日仏海洋学シンポジウム報告
日仏海洋学会および仏日海洋学会は 1983 年にフランスのモンペリエで第 1 回日仏海洋学シンポジウムを開催して以来，日仏交互にシンポジウムを重ね，本年，第 16 回日仏海洋学シンポジウムを日本で開催した．“The sea under human and natural impacts:
challenge of oceanography to the future Earth” をテーマとし，第 1 部を 2015 年 11 月 19-20 日に宮城県
塩竃市公民館本庁分室，第 2 部を 21 日に東京都恵比寿日仏会館で行なう 2 部構成とした．本シンポジウ
ムの前には三陸沿岸の復興，後には岡山県日生海域の里海に関するエクスカーションがフランス人参加者中心で行われた．
三陸のエクスカーションでは，11 月 17 日に陸前高
田市の巨大防潮堤の見学，気仙沼市唐桑のかき小屋での地元漁業者との懇談会を行い，11 月 18 日に南三陸町立サケふ化場，漁業協同組合の協力で志津川湾におけるギンザケとカキ養殖の現場視察を行った．その後，宮城県水産総合技術センターで水産業の復興状況についての紹介と議論を行い，松島湾の宮城県漁協鳴瀬支所カキ部会長渡辺茂氏のカキ処理場で意見交換を行った後，塩竈に移動した．
第 1 部では，パリでのテロで亡くなった犠牲者とフランス国民に対する黙祷を行ない，小松会長およびセカルディー会長の挨拶の後，震災の影響および復興に関する 5 題の基調講演が行われた．続いて口頭セッ
ション 19 演題およびポスターセッション 16 演題が発表された．第 1 部終了後，参加者は東京へ移動し，
11 月 20 日 19 時からフランス大使公邸での本シンポジウムを記念した大使主催のレセプションに招待された．レセプションでは海洋学水産学関係者も招待され，大使の代理であるフランス公使，小松会長の挨
拶の後，セッカルディ会長の乾杯の挨拶があり，美味なワインと食事が振る舞われ , 参加者の会話も弾み，
予定時間を過ぎた 21 時 30 分に散会した．
第 2 部では口頭セッション 5 演題が発表された．
その後，シンポジウムを総括し，今後の活動の方向性について検討した．午後には市民公開セミナーが“Historical relationship between France and Japan on

記事oyster culture, for the renovation of aquaculture in
Sanriku” をテーマとして行われた．多数の参加者があり，多くの議論が行われた．その後ワインと日本酒の試飲会とカキと蒲鉾の試食がフォワイエで行われ，室内楽の演奏も行われた．
11 月 22 日に朝から岡山県日生町に移動し，日生漁協が取り組んでいる里海活動について漁業協同組合の中心メンバーと NPO 法人里海づくり研究会田中丈裕氏と意見交換し，岡山で宿泊した．翌日東京に移動した．
シンポジウム参加者数は延べ 100 名（内フランス側
参加者 18 名）に達した．シンポジウムでは終始活発な議論と意見交換が行われ，大変な盛会となり，参加者にとって有意義なものとなった．本シンポジウムの講演論文集は 2016 年の出版を目指して準備を進める．
本シンポジウムは笹川日仏財団，日仏会館，東北区
水産研究所の共催で行われ，さらにフランス大使館をはじめとして多数の団体の後援，協賛，展示，広告のご支援を受けた．各団体に厚くお礼申し上げる．
以下に第 16 回シンポジウムを企画・実行した委員，
各種参加団体およびプログラムを掲載する．
Organizational committee
Prof. Teruhisa Komatsu（President SFJO Japan),Prof. Hubert-Jean Ceccaldi（President SFJOFrance), Prof. Shiro Imawaki（JAMSTEC), Dr.
Yves Henocque（IFREMER/SFJO France), Dr.
Patrick Prouzet（IFREMER/SFJO France),
Prof. Tsutomu Morinaga（SFJO Japan), Prof. Jiro
Yoshida（TUMSAT), Prof. Hiroshi Kouno（TUMSAT),Prof.
Yasuyuki
Koike （ex.
TUMSAT), Prof. Jota Kanda（TUMSAT), Prof.
Yuji Tanaka（TUMSAT), Prof. Hisayuki
Arakawa（TUMSAT), Prof. Yujiro Kitade（TUMSAT), Prof. Takeyoshi Nagai (TUMSAT),
Prof. Daigo Yanagimoto（Univ. Tokyo), Prof.
Toshiki Nakano（Tohoku Univ.), Dr. Hiroshi
Uchida（JAMSTEC), Prof. Kaoru Ichikawa

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La mer 53, 2015
（Kyushu Univ.), Prof. Mitsuru Hayashi（KobeUniv.), Prof. Tomoharu Senjyu（Kyushu Univ.),
Dr. Yutaka Okumura（FRA), Dr. Hideki Takami（FRA), Dr. Tetsuo Seki（SFJO Japan), Prof.
Kenji Ookoshi（Toho Univ.）

Scientific committee
Prof. Teruhisa Komatsu（President SFJO Japan),Prof. Hubert-Jean Ceccaldi（President SFJOFrance), Prof. Shiro Imawaki（JAMSTEC), Dr.
Yves Henocque（IFREMER/SFJO France), Dr.
Patrick Prouzet（IFREMER/SFJO France),
Prof. Tsutomu Morinaga（SFJO Japan）Prof. Jiro
Yoshida（TUMSAT), Prof. Hiroshi Kouno（TUMSAT),Prof.
Yasuyuki
Koike （ex.
TUMSAT), Prof. Jean-Claude Dauvin（UniversitéCaen), Dr. François Galgani（IFREMER/SFJO
France), Dr. Sandrine Ruitton（IFREMER), Dr.
Hervé Thébault（IRSN）
Organaizer : Société franco-japonaise d’ Océanographie Japan & FranceSponser : La Maison franco-japonaise, Fondation
Franco-Japonaise Sasakawa, Tohoku Nashonal
Fisheries Reseach InstituteSupport : The Japanese Society of Fisheries Science,
Tohoku branch of the JSFS, The Oceanographic Society of Japan, The Society of Fisheries
Oceanography, Miyagi Prefecture Fisheries
Technology Institute, Iwate Fisheries Technology Center, Fukushima Prefectual Fisheries
Experimental Station, Akita Prefectural Fisheries Promotion Center, Aomori industry technology center fisheries research institute, Fisheries Experimental Station of Ibaraki, Tohoku
University （Tohoku Ecosystem-AssociatedMarine Sciences), Tohoku University（Graduate school of agricultural science), AllianceFrancaise de Sendai, Japan Agency for MarineEarth Science and Technology, L’Ambassade
de France au Japon, Cable TV Marinet
Co-support : HUMANWEB Inc., Sanyo Techno Marine Inc., K-Engineering Co. LTD., IDEA
Consaltants Inc., Kokusai Kogyo Co. LTD.,
Toyo Corporation, Saikai Laboratory of Aqua-

culture and Technology Co. LTD., JFE Advantech Co. LTD., SEA-Plus Inc.
Advertisement : Kokusai Kogyo Co. LTD., Toyo
Construction Co. LTD., Amco Inc., Saikai
Laboratory of Aquaculture and Technology
Co. LTD., IDEA Consaltants Inc.
Exhibition : Amco Inc., The General Environmental
Technos Co. LTD., Saikai Laboratory of Aquaculture and Technology Co. LTD.
Cooperation : Japan Kotsu Co. LTD., OjimaKamabokoten Co. LTD., Saura Co. LTD.,
Pernod Ricard Japan K.K.
Program
17-18 November
・ Excursion
Tokyo-Ichinoseki-Rikuzentakada-Ishinomaki
Ishinomaki-Shizugawa-Shiogama
19 November, The Shiogama public hall
09h00 Opening address
09h00-09h15 Teruhisa KOMATSU President of
SFJO Japan
Challenge to resolve problems in the oceanand coastal waters in future Earth withstronger cooperation between the two Sociétés franco-japonaises d'Océanographie
09h15-09h30 Hubert-Jean CECCALDI Presidentof SFJO France
Evolution and progress accomplished during previous French-Japanese Symposiumsof Oceanography
Key note
Chairpersons Teruhisa KOMATSU &Hubert-Jean CECCALDI
09h30-9h50 : Key note 1-1 Hideki TAKAMI（FRA）
Challenges to revitalize the abalone Haliotis discus hannai fishery damaged by the2011 mega-earthquake and tsunami in Iwate
prefecture, northeastern Japan
Key note 1-2 Yutaka OKUMURA（FRA）
Influence of the Tsunami on the Coastal
Area of Miyagi Prefecture, Japan

学会記事
09h50-10h10 : Key note 2 Patrick PROUZET（IFREMER）
Ecological status of Atlantic salmon（Salmosalar）in France
10h10-10h30 : Key note 3 Hisayuki ARAKAWA（TUMSAT）
Explaining the reasons for the slower
decrease in radioactive concentrations insome fish species after the Fukushima
Daiichi Nuclear Power Plant Disaster10h30-10h50 : Key note 4 Hubert-Jean CECCALDI（SFJO France）
Future essential orientations in marine sciences and technology and cooperations between the two Sociétés franco-japonaisesd'Océanographie
Oral session
Session 1 Natural impacts and recovery of aquaculture
Chairpersons Yujiro KITADE（TUMSAT）& Sandrine RUITTON（MediterraneanInst. Ocean.）
11h05-11h20 Com-01 Mitsuru HAYASHI（KobeUniv.）
Shift of water quality in Osaka Bay by theresuspension of marine sediment caused bytsunami11h20-11h35
Com-02François
POISSON（IFREMER）
By-catch monitoring programme of theFrench Bluefin tuna longline fishery.
11h35-11h50 Com-03 Shinnosuke KAGA（Iwate
Fish.Tech.Ctr.）
On-site depuration of paralytic shellfish
poisoning toxins accumulated in the oyster
Crassostrea gigas in Ofunato Bay, Japan11h50-12h05
Com-04
Patrick
PROUZET（IFREMER）
The European eel（Anguilla anguilla）inFrance: An example of close cooperation
among researchers and fishers to study andmanage an endangered species.
12h05-12h20 Com-05 Yoshifumi TAKAHASHI（Kyushu Univ.）77
An analysis of the potential success for an
improved

Poster session
14h00-15h00
P-01 Mathias GIRAULT（Kanagawa Academy
Sci. & Tech.）：Automatic sorting system
and incubation at single plankton level
using microfluidic devices
P-02 Miwa YATSUYA（FRA）：Clearance ratesof Crassostrea spp. on oyster reef in temperate semi-enclosed Ariake Bay, westernJapan
P-03 Hidekazu SHIRAI（Sanyo Techno Marine,Inc.）：A high-resolusion unstructured grid
finite volume model for currents aroundnarrow straits of Matsushima Bay
P-04 Toshiki NAKANO（Tohoku Univ.）：Quantitative metabolome profiling of growth
hormone transgenic Coho Salmon
P-05 Ken HIGUCHI（TUMSAT）: Developmentof an underwater NaI（Tl）scintillation
spectrometer to monitor seabed radioactivity
P-06 Haruka SUZUKI（Tohoku Univ.）: Distributional changes in the kelp Eisenia bicyclis resulting from the subsidence and thelandfill for breakwater restoration after
the 2011 Tohoku Earthquake
P-07 Minoru TOMIYAMA（Aichi Fisheries Research Institute）: Factor analysis of upstream migrating Ayu in the Yahagi River
using machine learning
P-08 Yutaka OKUMURA（FRA）: Suitable quantity of oyster culture in Oginohama Bay,
Miyagi, Japan
P-09 Hikaru ENDO（Tohoku Univ.）: Combined
effects of nutrient availability, light intensity, and temperatureon the photosynthetic
pigments and color of the brown alga Undaria pinnatifida
P-10 Keiichi YAMAZAKI（TUMSAT）: Amplification of near-inertial period fluctuation
associated with passage of typhoon aroundthe Tango Peninsula, Japan

78

La mer 53, 2015

P-11 Hiroyuki TOGASHI（FRA）: The use of
stable isotopes for food web analyses: An
example of food webs in a coastal ecosystem
in Sendai Bay
P-12 Yuki KUBO（Tohoku Univ.）: Seasonal
movements of the herbivorous gastropod
Omhalius rusticus
P-13 Takuro NAKAGAWA（TUMSAT）: Relationship between patterns of fish behavior
and concentration of radioactive materials
after nuclear accident by the 2011 Great
East Japan Earthquake.
P-14 Yoshichika IKEDA（TUMSAT）: Development of a de-oiling process for seabed sediments
P-15 Teruhisa KOMATSU（Univ. Tokyo）: Trophic cascade of seaweed forests in Sanriku
Coast after the huge tsunami on 11 March2011
P-16 Gerard FOURNEAN（Aquitaine Landes
Récifs）: Implantation of artifi cial reefs on
the French Atlantic Coast
Session 2 Human impacts
Chairpersons
Hisayuki
ARAKAWA（TUMSAT） &Yves
HENOCQUE（IFREMER）
15h00-15h15 Com-06 Akira
MATSUMOTO（TUMSAT）
A feasibility study of an in situ fluorescence
spectroscopy system for the detection ofdeposited oil
15h15-15h30 Com-07 Hervé THÉBAULT (IRSN）
137Cs and Tritium Concentrations in
Seawater off the Fukushima Prefecture:
Results from the SOSO 5 Rivers Cruise（October 2014）15h30-15h45 Com-08 Jun SHOJI（Hiroshima
Univ.）Do species diversity and productivity offisheries resources increase around submarine groundwater seepages in coastal
area?: possible effects of global warming
15h45-16h00
Com-09FrançoisGALGANI（IFREMER）

Plastic in the Mediterranean Sea
Session 3 Promotion of cooperative research on
fisheries/oceanography between Japan andFranceChairpersons Ryo KIMURA(FRA)& Sandrine VAZ（IFREMER）
16h20-16h30 Opening address of the session:
Executive Director Fuminari ITOH（FRA）
16h30-16h45 Yves HENOCQUE（IFREMER）
Do our ocean policies make any difference
to the wellbeing of coastal communities?
16h45-17h00 Masahito HIROTA（FRA）
Fish and seafood value chains and the wellbeing for local community
17h00-17h15 Franck LAGARDE（IFREMER）
Synthesis of new knowledge about determinism of Pacific oysters（Crassostrea
gigas）larval recruitment in the Mediterranean Thau Lagoon
17h15-17h30 Masakazu HORI（FRA）
Challenge to harmonize sustainable fisherywith water-quality improvement using seagrass-oyster interaction in oligotrophic
coastal ecosystems
Banquet18h00-20h00 Ground palace Shiogama
20 November, The Shiogama public hall
Session 4 Challenge of oceanography
Chairpersons
Shiro
IMAWAKI（JAMSTEC）& Hervé THÉBAULT（IRSN）
09h00-09h15
Com-10YujiroKITADE（TUMSAT）
Recent research results and future projectin Antarctic Ocean by Umitaka-Maru research group for physical oceanography
09h15-09h30
Com-11
MathiasGIRAULT（Kanagawa academy of Sci. & Tech.）
Automatic sorting system and incubation at
single plankton level using microfluidic
devices
09h30-09h45 Com-12 Daigo YANAGIMOTO（Univ. Tokyo）

学会記事
Observation of near-bottom current on thecontinental shelf off Sanriku
09h45-10h00 Com-13 Jean-Claude DAUVIN（Université Caen）
The English Channel: towards a new Japanese Sea
Session 5 Coastal ecosystem and management
Chairpersons Yasuyuki KOIKE（SFJO
Japan）& Jean-Claude DAUVIN（UniversitéCaen）
10h15-10h30 Com-14 Sandrine RUITTON（Mediterranean Inst. Ocean.）Japanese vs. French artificial reefs: hightechnology vs. design to enhance ecologicalservices
10h30-10h45 Com-15 Satomi TAKAGI（Tohoku
Univ.）
Improvement of gonad quality of the sea
urchin Mesocentrotus nudus by shortterm cage culture
10h45-11h00 Com-16 Nelly FERROU & GérardFOURNEAU（Aquitaine Landes Récifs）
Artificial Reefs Installation along the Aquitaine Coast
11h15-11h30 Com-17 Sandrine VAZ（IFREMER）
Quantitative mapping of fish habitat: fromknowledge to spatialised fishery management
11h30-11h45 Com-18 Kazumi WAKITA（Tokai
Univ.）
Perceptions of marine ecosystem services:
A case study from remote islands,
Taketomi Town
11h45-12h00 Com-19 Catherine
BOISNEAU（UMR CITERES）
Amphidromous Fishes Management inContinental Waters. The Need for an
Integrated Approach
Reception at The Embassy of France in Japan（11-44, Minami Azabu-4, Minato, Tokyo）

79

21 November, The hall of Nichifutsu Kaikan（LaMaison Franco-Janonaise）in Ebisu
Session 6 Aquaculture
Chairpersons Tetsuo SEKI（AFFTIS）&
François GALGANI（IFREMER）
10h00-10h15 Com-20 Hirokazu ABE（FRA）
Larval and Juvenile Dynamics of theManila Clam Ruditapes philippinarum in
Matsushima Bay and Mangoku-ura Inlet,
Northeastern Japan, Following 2011
Tsunami Disaster10h15-10h30 Com-21 Catherine MARIOJOULS（AgroParisTech）
Certification Schemes for Sustainable
Aquaculture and Feeding
10h30-10h45 Com-22 Waka SATO-OHKOSHI（Tohoku Univ.）
Ecological impacts of the 2011 earthquake
and tsunami on the subtidal macrobenthic
community in Onagawa Bay, northeasternJapan
10h45-11h00 Com-23 Jean-Claude DAUVIN（Université Caen）
One year colonisation by zoobenthic species
on an eco-friendly artificial reef in the
English Channel intertidal zone
11h00-11h15 Com-24 Rena SHIBATA（FRA）
Retinomotor and stress responses of marbled sole Pleuronectes yokohamae under
the LEDs
11h30-12h00 Summarize of Symposium
Chairpersons Presidents of SFJO Japan &FranceGroup photographOpen Seminar for Public（with interpretation）
PM, 21 November, The hall of Nichifutsu Kaikan（LaMaison Franco-Janonaise）in Ebisu
Historical Relationship between France and Japanon Oyster Culture, for the renovation of aquaculture
in Sanriku

80

La mer 53, 201513h30-13h40 Opening address
Teruhisa KOMATSU（President of SFJO-J）
13h40-14h10 History and Solidarity on Oyster
Culture in both countries
Yasuyuki KOIKE（ex. Prof. of TUMSAT）
14h10-14h40 Situation of Oyster culture in France.
Dr. Catherine MARIOJOULS（Agro.Paris.Tech）
15h00-15h30 Situation and new trial on Oyster
culture in Japan.
Tetsuo SEKI（AFFTIS）
15h30-16h00 New challenge on commercializationand culture technique of Oyster in Japan:
Ms. Kyoko WASHIASHI（Oyster innovation Co. Humanweb）
16h00-16h30 Cooporation between France and Japon
on Oyster culture and future prospects.
Franck LAGARDE（IFREMER）
16h30-17h00 Discussion
17h00-17h15 Closing address
Prof. Hubert-Jean CECCALDI（President of SFJO-F）
17h30 Cocktail（with concert of the flute）

場 所：東京海洋大学 9 号館 203 号室
参加者：小松，森永，小池，荒川，内田，奥村，田中，本多（事務）（1）報告事項① 日本水産学会誌「水産研究のフロントから」が紹介された．
（小松）（2）協議事項① 総会議題および評議員議題の確認
1）2014 年度収支決算および 2015 年度予算案について確認した．
2）学会賞規定の今脇修正案について検討し，一部の文言修正し承認した．
3）2015 年度日仏海洋学会役員リストを確認した．
4）学会費滞納者リストを確認した．事務局から入金依頼を再度行うことにした．
5）会員には総会議案，評議員には総会議案と評議員会議案を委任状と一緒に送付することとした．
② Yves HENOCQUE 博士の受章記念講演を学会
賞記念講演の前の時間帯に 30 分間お願いすることにした．

2．幹事会議事録
・第 1 回幹事会議事録
日 時：2015 年 4 月 6 日（月）10 時 30 分～ 12時00分
場 所：東京海洋大学 9 号館 207 号室
参加者：小松，今脇，森永，小池，河野，荒川，内田，柳本，本多（事務）（1）報告事項① 総会，評議員会，研究発表会 6 月 27 日（土）に決定した．
② 日仏工業技術会の研修に関してその見学地として JAMSTEC が挙げられている．その協力依頼に関して，今脇顧問の紹介により見学が行なわれる予定である．
（2）協議事項① 研究発表の締め切り日程，参加費などについて
日付などの修正ののち承認した．懇親会場は次回までに決定．
② 学会賞受賞規則変更案を原案の通り承認した．

・第 3 回幹事会議事録
日 時：2015 年 6 月 2 日（火）15 時 00 分～ 16 時
45 分
場 所：東京海洋大学 9 号館 203 号室
参加者：小松，河野，森永，小池，吉田，荒川，内田，奥村，本多（事務）（1）報告事項① 日仏海洋学会総会と評議員会の案内状に議案と委任状を添付して事務局より発送済みの報告がされた．
（2）協議事項① 総会議案 第一号議案 2014 年度事業報告（その他）に評議員会での決定事項（賞規定の改訂
および会員の除名）を追加するかについてメール幹事会議をすることとした．
② 一般社団法人学術著作権協会より電子的複製権の管理委託の承認について，荒川庶務幹事より他学会の対応策を聞いてもらい，メール幹事
会議をすることとした．

・第 2 回幹事会議事録
日 時：2015 年 5 月 1 日（金）15 時 00 分～ 16
時45分

・第 4 回幹事会議事録
日 時：2015 年 7 月 28 日（火）10 時 00 分～
場 所：東京海洋大学 9 号館 203 号室

学会記事
参加者：小松，今脇，關，小池，荒川，内田，奥村，本多（事務）（1）報告事項① 6/27（土）日仏海洋学会総会および学術研究発
表会を行なった．議事録は，La mer 次号へ掲載予定．
② 一般社団法人学術著作権協会より電子的複製権の管理委託の承認についてメール持ち回り
会議にて審議し，承認を得たので委託することとした．
（2）協議事項① 日仏海洋学会誌「うみ」投稿規定について，一部の不明瞭な文言や古い表現を改めることとした．吉田編集委員長と庶務幹事で原案を作成することとした．
② 日仏海洋学会会則の一部改正について，第 7 条に会計年度を追記する件が提案され次回までに改定案を検討することとした．
③ 日仏海洋学会賞および日仏海洋学会論文賞の英語表記について検討し，以下のように決定した．
学会賞：La Societe franco-japonaise d'oceanographie Prize
論文賞：La Societe franco-japonaise d'oceanographie Excellent Article Award・第 5 回幹事会議事録
日 時：2015 年 9 月 17 日（木）10 時 30 分～ 12
時 45 分
場 所：東京海洋大学 9 号館 203 号室
参加者：小松，今脇，森永，河野，小池，荒川，奥村，本多（事務）（1）報告事項① 日本学術会議水産・海洋研究連絡協議会より名古屋議定書により生じる水産・海洋分野の問題
点の洗い出しに関する WG の立ち上げに際し
日仏海洋学会は参加，（幹事持ち回りメール会議）することとし，推薦された奥村裕委員にWG 委員を委嘱した．第 1 回は 8 月 27 日に東京海洋大学で開催されたが，出張のため出席できなかった．本会議の報告は後日行なうこと
とする．
（奥村）
② 2015 年度賞委員長選考依頼を行なった．（小松会長）

81（2）協議事項① 投稿規程などの改定について日本語版，英語版が提案された．投稿が誰でもできるように変更することが提案されているが会員に限定するべき．その代わりに論文が印刷されたらすぐにホームページでオープンにする方が会員の獲得につながるのではないか？（河野）再度，編集委員長と庶務幹事で相談することとした．
② 会則に学会の会計年度を明記する旨の改定案が示されたが，事業年度として明記する方がよ
いのではないかとの意見があり（今脇），次回
幹事会に再提案することとした．
3．2015 年度（第 56 回）日仏海洋学会総会議事録
日 時：2015 年 6 月 27 日（土）14 時 40 分～ 15
時 50 分
場 所：公益財団法人 日仏会館 会議室 501 号
室
議事に先立ち総会の成立要件の確認を行ない，出席 87 名（会議参加 22 名，委任状による出席 65 名）により本総会は成立（会員数 130 名の 1/6 の出席）が確認された．
議 長：小松会長
第 1 号議案 2014 年度事業報告（荒川庶務幹事）（1）庶務関係
会員異動状況について 2014 年度会員数
は不変．
（2）活動状況① 評議員会 1 回（6/14 日仏会館），幹事会 7 回（4/30，10/3，11/4，12/12，1/15，2/9，3/2 東京海洋大学）），総会 1 回（6/14），学術研究発表
会 1 回（6/14），第 16 回日仏海洋学シンポジウ
ム実行委員会 4 回（12/12，1/15，2/9，3/2 東京海洋大学）を開催．
② 日仏関連学会連絡協議会（6/16 日仏会館－小松会長出席，12/8 日仏会館－小松会長，荒川庶務幹事出席），水産・海洋科学研究連絡協議会（5/21 東 京 海 洋 大 学 － 小 松 会 長 出 席，
11/17 東京海洋大学－河野副会長，荒川庶務
幹事出席）③ 学会賞選考委員半数改選を実施④ 論文賞 2 件を授与
（3）編集関係
学会誌「La mer」52 巻 1-2 号，52 巻 3 号，52

82

La mer 53, 2015

巻 4 号を発刊（4）その他① 学会賞規定の一部改正② 会費未納により会員一名を除名（会則第 8 条（2））
各報告と質疑ののち，第 1 号議案は承認された．
第 2 号議案 2014 年度収支決算報告および監査報告（1）2014 年度収支決算が会計幹事代理（荒川庶務幹事）より資料 1 に従って報告された．
（2）宮崎監事から監査の結果，会計が適正であると報告された．
質疑ののち，第 2 号議案は承認された．
第 3 号議案 2015 年度事業案（（1）-（5）荒川庶務幹事 ,（6）吉田編集委員長）（1）総会 1 回，学術研究発表会 1 回，評議員会 1
回，幹事会 4 回，第 16 回日仏海洋学シンポジ
ウム実行委員会 8 回 開催（予定）（2）第 16 回日仏海洋学シンポジウム開催（2015 年
11 月 16 ～ 21 日）（3）2015 年度学会賞，論文賞の授与（4）2016 年度学会賞，論文賞の候補者の推薦（5）評議員選挙，会長選挙，学会賞委員半数改選（6）学会誌「La mer」53 巻 1-4 号の発刊予定と編
集状況報告
各項目の説明と質疑ののち，第 3 号議案は承認された．
第 4 号議案 2015 年度予算案
2015 年度予算案が会計幹事代理（荒川庶務幹事）により資料 2 に従って説明された．
審議ののち，第 4 号議案を承認された．
第 5 号議案 2014-2015 年度役員，評議員，学会賞推薦委員（荒川庶務幹事）
学会賞選考委員半数改選の結果について報告された．
学会賞選考委員として当選した小松委員から辞退の申し出があり，次点の千手会員を選出した．第 5 号
議案は承認された．
第 6 議案 第 16 回日仏海洋学シンポジウム（小松会長）
第 16 回日仏海洋学シンポジウムの概要および準備の進捗状況の説明を行なった．
（1）テーマ：“The sea under human and natural
impacts: challenge of oceanography to the
future Earth”（2）市民シンポジウムテーマ：「日仏 海の幸文化―三陸の復興に向けて―（仮）」（3）開催時期：2015 年 11 月 17-18 日 エクスカーション
2015 年 11 月 19-20 日 日仏海洋学シンポジウム Part 1（塩竃）2015 年 11 月 21 日 日仏海洋学シンポジウム Part 2，日仏市民シンポジウム（日仏会館）（4）開催場所：塩釜市役所公民館本町分室 / 塩竈市杉村惇美術館，日仏会館（東京）（5）内容：① エクスカーション（宮城県沿岸見学，カキ養殖
復旧状況，巨大防波堤，沿岸の現況調査，漁業者との意見交換等）② 塩釜市役所公民館本町分室にて基調講演とシンポジウム③ フランス大使館にてレセプション④ 日仏会館にて市民シンポジウム（6）主催：日仏海洋学会，仏日海洋学会（7）共催：公益財団法人日仏会館，笹川日仏財団，
水産総合研究センター東北区水産研究所（8）後援：日本海洋学会，日本水産学会，日本水産学会東北支部，水産海洋学会，福島県水産試
験場，岩手県水産技術センター，秋田県水産振興センター，宮城県水産技術総合センター（決定済みのみ）質疑を行った後，第 6 号議案は承認された．
報告事項
第 15 回日仏海洋学シンポジウムの概要の記事が，日本水産学会誌 81 巻 3 号に掲載されたことについて中野俊樹会員より報告された．
4．2014 年度学術研究発表会
日 時：2015 年 6 月 27 日（土）9 時 30 分~14 時
30 分
場 所：日仏会館 501 会議室
プログラムは以下の通り．
9：30 ～ 10：00 座長 飯淵敏夫（海生研）① 福島県いわき市沿岸の海藻群落の放射性物質濃度○重岡柚1，浅田みなみ1，松本陽1，荒川久幸1，
榎本昌宏2（1海洋大院，2福島水試）② 高効率 NaI（Tl）結晶を用いた曳航型放射性物質センサー（S-RAM）の開発○樋口謙1，荒川久幸1，松本陽1，

学会記事
守岡良晃2（1海洋大院，2福島水試）
10：00~10：30 座長 中野俊樹（東北大学）③ 千葉県館山湾における温帯性サンゴ Alveopora
japonica の短期個体群動態○橋本匠平，松本陽，荒川久幸（海洋大院）④ クロミンククジラとミンククジラ頭骨における形態学的新知見○中村玄1，藤瀬良弘2，加藤秀弘1
1（ 東京海洋大学大学院，2(一財）日本鯨類研究所）
10：30 ～ 11：00 フランス勲章受章記念講演“The bumpy road from science to policy”

Dr. Yves Hénocque（Ifremer）

13：00 ～ 13：30 座長 内田 裕（JAMSTEC）⑤ Introduction to microfluidic sorting system in
Oceanography○ M. Girault, A. Hattori, H. Kim, K. Matsuura,
M. Odaka, H. Terazono, K. Yasuda（Kanagawa academy of science and technology）⑥ Spatial and temporal variations in the microscale vertical distributions of plankton in upper
layers○ J. Zhang1・T. Akiba2・
Y. Tanaka1（1TUMSAT,2AIST）
13：30 ～ 14：30 座長 千手智晴（九州大学）⑦ サメ類を漁獲対象とした調査用縦延縄採集具の開発について○上嶋紘生1，戸高耀介2，生井沢知佳2，栗原芳恵1，
宮崎唯史1，塩出大輔2，吉田次郎2，根本雅生2（1海洋大練習船，2海洋大院）⑧ 南西諸島東方海域における浮延縄試験操業○戸髙耀介1，古見拓郎1，梶浦俊樹1，塩出大輔1，
上嶋紘生2，萩田隆一2，林 敏史2，吉田次郎1，
根本雅生1（1 海洋大院，2 海洋大練習船）⑨ A Note on GK filter: Contamination of double
diffusive convection in overturning○ Haruka Nakano and Jiro Yoshida（TUMSAT）⑩ 相模湾北部における表層循環流関する研究○陳 褘寧，中野知香，根本雅生，吉田次郎（海洋大院）
14：40 ～ 15：50 総会
16：00 ～ 16：10 2015 年度日仏海洋学会賞および論文賞授与式≪学会賞受賞≫ 千手智晴会員（九州大学）「日本海の深層水の形成・循環・変質過程に関する研究」≪論文賞受賞≫ 大村卓朗会員（東大大海研）「Current status of ballast water and aquaticorganisms transferred from and to Japan」50

83

巻 1-2 号，11-22，2012≪論文賞受賞≫ 中野知香会員（海洋大院）「Parameterization of the eddy diffusivity due todouble diffusive convection」51 巻 1-2 号，
13-29，2013
16：10 ～ 16：50 2015 年度日仏海洋学会賞記念講演
千手智晴会員
17：00 ～ 19：00 懇親会（オトラ アネックスにて）
5．訃報
本学会名誉会員，佐伯和昭先生は 2015 年 2 月にご逝去されました．長年にわたって庶務や渉外幹事を歴任し，2008 年度より名誉会員となられました．心より哀悼の意を表し，謹んでご報告申し上げます．
6．新入会員
氏 名

所 属

紹介者

阿部 博和

国立研究開発法人水産総合研究センター 東北区水産
研究所

奥村 裕

上嶋 紘生

東京海洋大学 船舶運航センター青鷹丸

吉田 次郎

秋葉 龍郎

産業技術総合研究所

田中 祐志

公益財団法人 神奈川科学
Mathias GIRAULT
技術アカデミー

荒川 久幸

張 峻徳

東京海洋大学 応用環境シ
ステム学専攻 浮遊生物研
究室

田中 祐志

髙橋 義文

九州大学大学院 農学研究
院 農業資源経済学部門

奥村 裕

小針 統

鹿児島大学 水産学部 水
吉田 次郎
圏科学分野

樋口 謙

東京海洋大学 海洋環境保全学専攻 環境測定学研究
室

荒川 久幸

大草 駿

東京海洋大学 海洋環境保全学専攻 環境測定学研究
室

荒川 久幸

重岡 柚

東東京海洋大学 海洋環境保全学専攻 環境測定学研
究室

荒川 久幸

劉 軒禹

東京海洋大学 海洋環境保全学専攻 環境測定学研究
室

荒川 久幸

84

La mer 53, 2015

7．所属および住所変更
氏 名

新しい所属先・住所

谷田 巌

東京大学大学院農学生命科学研究科
水圏生物環境学研究室 特任研究員

渡部 俊広

国立研究開発法人 水産総合研究センター

中村 真由子

国立研究開発法人 海洋技術安全研究
所

JFE アドバンテック
株式会社

兵庫県西宮市高畑町 3-48

8．退会（逝去者含む）
佐伯和昭，有木瑞紀，明瀬太志，戸口和貴，那須野陽平，信幸建設株式会社（賛助）
9．寄贈図書Ocean Newsletter（海洋政策研究財団）；No. 350-367
RESTEC News（一般財団法人リモート・センシング
技術センター）；第 6 号
なつしま（JAMSTEC）；通巻 349 号～ 353 号
農工研ニュース（農村工学研究所）；No. 95-99
増養殖研究レター（水産総合研究センター）；第 5 号
国立科学博物館研究報告 A 類（動物学）；第 401 巻第
1 号-第 3 号
Ocean Breeze（東京大学大気海洋研究所）；第 18 号第 20 号
気候システムニュース；2015. 2, No. 4
CIC NEWSLETTER（東京大学）；No. 12FRANEWS（水産総合研究センター）；No. 41-44
神奈川県立博物館研究報告自然科学（神奈川県立生命の星・地球博物館）；44 号
水産技術（独立行政法人水産総合研究センター）；第 7
巻第 2 号-第 8 巻第 1 号
水産総合研究センター研究報告；No. 39-40
Techno-ocean News（テクノオーシャンネットワー
ク）；No．56-57
海洋白書 2015 日本の動き 世界の動き「海洋立国」のための海洋政策の具体的実施に向けて（海洋政策研究財団）
日仏生物学会 会報；No. 54, 2014
東京大学大気海洋研究所 要覧・年報 2015
農村工学研究所報告（農村工学研究所）；第 54 号
広島日仏協会報 BULLETIN No. 197
国立研究開発法人産業技術総合研究所地質調査総合センター 2015 沖縄島北部周辺海域海洋地質図
国立研究開発法人産業技術総合研究所地質調査総合センター 2015 室蘭沖表層堆積図
PEOGRESS IN FISHERY SCIENCES（中 国 水 産 学会）；第 16 巻第 4 期
Oceanologia et Limnologia Sinica（中国海洋湖沼学会・
中国科学院海洋研究所）；第 46 巻第 1 期～第 3 期
農村工学研究所成果情報（農村工学研究所）；平成 26
年度

学会記事

85

平成 26 年度収支決算
収入の部
費

目

予算額（A） 決算額（B） 増減（B)－(A）前年度繰越金1,464,206

1,464,206

正会員会費

880,000

872,000-8,000 8,000 円× 109 名

特別会員

96,000102,000

6,000 6,000 円× 17 名

学生会員会費24,00012,000-12,000 4,000 円× 3 名

賛助会員会費80,000110,000

30,000 10,000 円× 11 口（7 社）

学会誌売上金150,000

161,201

11,201

広 告 費

20,0000-20,000

論文印刷費・カラー印刷費

600,000

548,000-52,000 9 論文

別刷り印刷費90,000125,300

35,300 7 論文

雑 収 入

100,000

116,600

16,600 学術著作権使用料他

寄 付 金

0

0

0

3,504,206

3,511,307

7,101

収入合計

摘

要

摘

要

0

支出の部
費

目

予算額（A） 決算額（B） 増減（B）－（A）学会誌印刷費1,800,000

969,286-830,714 52（1.2），52（3），52（4）

送料・通信費100,000

44,893-55,107

事 務 費

700,000

695,492

交 通 費

20,0002,202-4,508 事務用品，人件費（通勤手当含む）-17,798 事務局～日仏会館

会 議 費

5,000

1,308

-3,692

学会賞経費

30,00019,850-10,150 賞状他

雑費

25,00026,224

次年度繰越

824,206

1,752,052

927,846

1,224 振込手数料他

支出合計

3,504,206

3,511,307

7,101

86

La mer 53, 2015

平成 27 年度予算
収入の部
費目

2015 年度予算（B） 2014 年度予算（A） 増減（B）－（A）摘要前年度繰越金（銀行残高）

1,752,052

1,464,206

287,846

正会員会費

888,000

880,000

8,000 8,000 円× 111 名

特別会員

108,000

96,00012,000 6,000 円× 18 名

学生会員会費28,00024,0004,000 4,000 円× 7 名

賛助会員会費80,00080,0000 10,000 円× 8 口（7 社）

学会誌売上金150,000

150,000

0

広告費

20,00020,0000

論文印刷費・カラー印刷費

600,000

600,0000

別刷り印刷費90,00090,0000

雑収入

100,000

100,0000

寄付金

1,700,000

01,700,000

収入合計

5,516,052

3,504,206

2,011,846

シンポジウム助成（笹川日仏財団 100 万円，
日仏会館 70 万円）

支出の部
費目

2015 年度予算（B） 2014 年度予算（A） 増減（B）-（A）学会誌印刷費1,020,000

1,800,000

送料・通信費100,000

100,000

事務費

700,000

700,000

交通費

10,00020,000-780,000 53(1.2)340,000 円請求予定，年 3 回発行で積算
00 事務用品，人件費（通勤手当含む）-10,000 事務局～日仏会館

会議費

5,000

5,000

0

学会賞経費

30,00030,000

0

雑費

摘要

25,00025,0000

シンポジウム事業費

1,800,000

01,800,000

次年度繰越（予備費）

1,826,052

824,206

1,001,846

支出合計

5,516,052

3,504,206

2,011,846