Laguna (2019) 26: 27-38

ISSN 2185-2995

Response of benthic foraminifera (Rhizaria) to anthropogenic
environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera
Hiroyuki Takata1,2, Toshiaki Irizuki3, Koji Seto2 and Ritsuo Nomura4

Abstract: We investigated faunal transitions in living (rose Bengal-stained) benthic foraminifera
in the Honjo area of Lake Nakaumi (southwestern Japan) through monthly biological monitoringat a fixed station (approx. 8-m depth) to study the dispersal potential of benthic foraminifera.
We observed the following transitions in benthic foraminifera: (1) few and sporadic occurrencesof benthic foraminifera before November 2007; (2) Ammonia “beccarii” forma 1 dominant in2008 and 2009 with occasional occurrences of Miliammina fusca; and (3) Trochammina hadai

dominant from 2010 on, with occasional occurrences of Elphidium somaense and M. fusca. Young

individuals of A. “beccarii” forma 1 likely settled in the Honjo area in winters of both 2007/2008
and 2008/2009 as a result of widening and deepening of the southwestern channel. The young

individuals seemed to grow in spring and summer, but likely died out toward fall, probably becauseof oxygen deficiency. The channel constructions, opening dikes isolating the Honjo area, in 2007–2008 and May 2009 could explain the dramatic changes in benthic foraminiferal fauna, especiallythe change in the dominant species from A. “beccarii” forma 1 to T. hadai through a shift in theprovenance of the individuals supplied from Lake Nakaumi.

Key words: neritic benthic foraminifera, Honjo area of Lake Nakaumi, dispersal potential, artificial
environmental changes

1Marine Research Institute, Pusan National University, 2 Busandaehak-ro 63 beon-gil, Busan 46241, Korea.

2

Estuary Research Center, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.

3

Institute of Environmental Systems Science, Academic Assembly, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.

4

Faculty of Education, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.

受付日：2019 年 9 月 30 日，受理日：2019 年 11 月 21 日，WEB 掲載日：2019 年 12 月 31 日

27

Hiroyuki Takata・Toshiaki Irizuki・Koji Seto・Ritsuo Nomura

Nakaumi and the Honjo area.

Introduction

These circumstances make biological monitoring ofBenthic foraminifera (Rhizaria) are widely distributed

modern benthic foraminifera in the Honjo area an ideal

tests can be preserved in past sediments as fossils,

benthic foraminifera. In this paper, we report the faunal

in intertidal to deep-sea environments. Because theircase study for learning the dispersal potential of neritic

faunal analysis of benthic foraminifera has been atransition of living (stained) benthic foraminifera at one

useful approach for considering past environmental

fixed station in the Honjo area every month from 2006 to

conditions. However, because ecological information

2011.

about benthic foraminifera is still sparse, it is important
to study modern benthic foraminifera for precise

Study area, materials and methods

paleoenvironmental interpretation.

Recently, the dispersal potential of benthic foraminifera

La ke Na kaum i is a brack ish-water lagoon i n

has been noted as a n i mpor t a nt a rea for st udy,

southwestern Japan (Fig. 1) with an average water depth

are some exceptions, most benthic foraminifera lack aderived mainly from the Hii River and transported

particularly in neritic environments. Although thereof 5.4 m. Its water inputs include oligohaline water,

planktonic juvenile stage (see Alve, 1999, and references

through the Ohashi River and Lake Shinji (Fig. 1), andtherein), but propagules (tiny juveniles) are important forseawater from the Sakai Channel. Its hypolimnion

benthic foraminiferal ecology (Alve and Goldstein, 2003,

has a salinity of around 27 and experiences a decline2010) because they may be dispersed long distancesin dissolved oxygen content in summer and fall. The

during several months of dormancy. Benthic foraminifera

lagoon substrate consists mainly of organic-rich muddy

may therefore have significant dispersal potential throughsediments (e.g., Sampei et al., 1997; Sakai et al., 2013).
The “Honjo area” is located in the northwestern part ofdispersal and reactivation of propagules. In addition,living (rose Bengal-stained) benthic foraminifera have

Lake Nakaumi (Fig. 1). This area had been separated

been found in organic-matter aggregates suspended infrom the main part of Lake Nakaumi since 1981

the water column of Lake Nakaumi (southwestern Japan)

by several dikes, except for narrow channels at the(Nomura and Seto, 2004). Dispersal with organic-matter

southwestern and northern parts (e.g., Nomura and Seto,

aggregates also seems plausible for benthic foraminifera.

2002). In 2007–2008, the southwestern channel near the

It is usually difficult, however, to evaluate dispersal

Ohmisaki Dike was widened and excavated (Fig. 1), andmechanisms of benthic foraminifera under naturalthen in May 2009 a new channel was opened through theconditions, including those involving reactivation ofMoriyama Dike. Nomura et al. (2013) studied the radiumpropagules, because it is difficult to distinguish newisotope ratio (224Ra/228Ra) of the lagoon waters in Lakesettlements of dispersed individuals from the extant

Nakaumi and the Honjo area and reported the general

population. For example, faunal transitions of living

seasonal variations. They recognized perturbation of(stained) benthic foraminifera have been observed in

the seasonal variations in this isotope ratio in the Honjo

area, which reflected a new circulation pattern after thethe Honjo area of Lake Nakaumi, southwestern Japan.
This lagoon has been modified artificially several times

opening of the channel through the Moriyama Dike induring the last century (Figs. 2 & 3 in Nomura, 2003). In

May 2009.

particular, the Honjo area had been largely isolated from

Environmental profiles of the lagoon water at fixed

the main part of Lake Nakaumi since 1981 by several

station M-9 (133°31.53ʹN, 133°10.79ʹE, approx. 8 m

had almost disappeared in the Honjo area (Nomura andmonitoring results (K. Seto, unpublished data). The

water depth; Fig. 1) were recorded along with biologicaldikes (e.g., Nomura and Seto, 2002). Benthic foraminifera
Seto, 2002). Recently (in the late 2000s), new channels

temperature of the hypolimnetic water shows seasonal

were constructed in the southwestern and northeasternvariations, ranging between 3 and 29 °C (Fig. 2),

parts of the Honjo area, close to the Ohmisaki Dike andsimilar to those of mean air temperature recorded atthrough the Moriyama Dike, respectively. As a result,

Sakai Weather Station (approx. 8 km ENE of the Honjo

exchange of lagoon waters has resumed between Lake

area) (Japan Meteorological Agency: http://www.data.
28

Response of benthic foraminifera (Rhizaria) to anthropogenic environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera

145°
45°

(a)

133°00'(b)

10'
Sakai Channel

Hii
River

(c)

(b)
Lake Shinji

Tokyo

OhashiRiver

NW
Pacific
133°10´

LakeNakaumi

35°
30'

25'

ha
nn
el

133°12´C

133°8´

20'

Sa
ka
i

35°32´Moriyama
Dike

5m

M-9
5m

Honjo area
5m

5m

35°30´5m

Ohmisaki
Dike
5m

(c)

Lake Nakaumi

2.5 km(d)Fig. 1 (a) Locations of our study area, (b) Lake Shinji-Nakaumi system, (c) the Honjo area (modified

from Nomura et al., 2015) and (d) recent distributions of Ammonia “beccarii” forma 1 andTrochammina hadai (referring from Nomura et al., 2013). Open and filled circles in (c) show station

M-9 and other fixed stations in our study, respectively. Dark and light shading in (d) correspond to
the areas of negatively and positively high factor loadings of the Ammonia “beccarii” assemblage
and Trocammina hadai assemblage during the 1980s to 1996 in Nomura (2003), respectively.

jma.go.jp/gmd/risk/obsdl/index.php). In contrast, there

sediment surface using an acrylic tube (6-cm inner

hypolimnetic water, although the salinity increased

single sample (i.e., 113 cm3 total volume).

were no obvious seasonal salinity variations of thediameter). The four replicates were combined into amarkedly in May 2009 and remained elevated thereafter

The meiobenthic subsamples were washed through a(Fig. 2). Dissolved oxygen content of the hypolimnetic

250-mesh sieve (62-μm openings). The residues weresummer and fall (Fig. 2), although the summer and fall

after which they were washed with warm water to remove

water showed seasonal variations with lower values instained with rose Bengal solution (0.5 g l–1) for 24 hours,

values tended to increase beginning in 2009. Thus, there

excess dye (Oda, 1978), and dried at 50 °C. Living

were obvious changes in salinity and dissolved oxygen in(stained) foraminiferal specimens were collected fromthe hypolimnetic water at station M-9 beginning in May

the residues and were identified under a stereo-binocular2009 after the opening of the northeast channel throughmicroscope. Samples from 5 December 2006, 30 January

the Moriyama Dike.

and 26 February 2007, 26 January and 19 February

We used an Ekman-Birge type sampler to collect a2008, and 22 February 2009, were not analyzed in thissurface-sediment sample monthly from the lagoon floor

study. Taxonomic assignments followed Matoba (1970)

at fixed station M-9 from May 2006 to May 2011. Fourand Nomura and Seto (1992). Generic classification was

replicate meiobenthic (ostracod and foraminiferal) sub-based on Loeblich and Tappan (1987). The number ofsamples were taken from the uppermost 1 cm of thespecimens per unit volume (# cm –3) was calculated for29

Hiroyuki Takata・Toshiaki Irizuki・Koji Seto・Ritsuo Nomura
30

Mean air 20
temperature
(ºC)
10
0
12
6

Mean windvelosity(m s-1)

2

Maximum
northwesterlywindvelosity4(m s-1)

0

0

8

4

30

Water
20
temperature
(ºC)
10

30

Salinity
20

10

0

May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May

Dissolved
oxygencontent (mg l-1) 5

2006

2007

2008

2009

2010

2011

Fig. 2 Daily variations of mean air temperature and mean wind velocity with maximum northwesterly windvelocity at the Sakai Weather Station of the Japan Meteorological Agency (data referred from website of theJapan Meteorological Agency: http://www.data.jma.go.jp/gmd/risk/obsdl/index.php) and seasonal variations ofwater temperature, salinity and dissolved oxygen content of the hypolimnetic water at station M-9, the Honjo
area, Lake Nakaumi.

each species in each sample. The test diameters of living“beccarii” (Linné) forma 1 and Trochammina hadai

using a micrometer under a stereo-binocular microscope.

Miliammina f usca (Brady), Elphidium somaense(stained) Ammonia “beccarii” forma 1 were measured by

Uchio were common constituents (Fig. 3; Appendix).

Because the foraminiferal tests were sometimes broken,

Takayanagi and Ammonia “beccarii” (Linné) forma 2

we made separate tallies of perfect and broken tests

occurred sporadically at lower numbers during our study

during size measurements.

interval (Fig. 3; Appendix). All of these species havebeen commonly reported from Lake Nakaumi and the
Sakai Channel (Nomura and Seto, 1992, 2002).

Results and discussion

Ammonia “beccarii” forma 1 was found almost

Living (stained) benthic foraminifera were found incontinuously throughout the study interval (Fig. 4). The

most of the samples during our study period. Ammonia

occurrence of this species was very low and sporadic30

Response of benthic foraminifera (Rhizaria) to anthropogenic environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera

Fig. 3 Light micrographs of benthic foraminifera in the Honjo area, Lake Nakaumi, southwestern Japan.
1a–c. Trochammina hadai Uchio; 2a–c. Ammonia “beccarii” (Linné) forma 1; 3. Miliammina fusca (Brady);
4. Elphidium somaense Takayanagi. Scale bars = 100 µm.

until November 2007, in agreement with earlier studiesof larger individuals (300–480 µm) increased in May

then it became dominant at station M-9, especially innumber within a half year. This pattern is consistent withby Nomura and Seto (2002) and Nomura (2003), andand June 2008, and March and April 2009, decreasing in2008 and 2009. In addition, the abundance of this species

the trend of decreasing abundance of this species toward

decreased toward fall both in 2008 and 2009 (Fig. 4).

fall (Fig. 4). In contrast, the medium-sized individuals

In contrast, T. hadai became dominant beginning in(240–300 µm) were continuously common from July to2010 (Fig. 4). Miliammina fusca was continuously foundNovember 2009. Despite the generally low abundance ofin the 2008/2009 winter, whereas E. somaense wassmall individuals in 2010 and 2011, they were common

continuously present in the 2009/2010 winter. Thus, thein March 2011.

faunal transition of living (stained) benthic foraminifera

Based on the abundance and size distribution of living

at station M-9 was as follows: (1) few and sporadic

A. “beccarii” forma 1, we suggest that young individuals

2007, (2) dominant A. “beccarii” forma 1 during 2008

both 2007/2008 and 2008/2009. The young individuals

occurrences of benthic foraminifera prior to Novemberof this species settled at station M-9 in the winters ofand 2009 with sporadic occurrences of M. fusca, andseemed to grow during the following spring and summer(3) dominant T. hadai from 2010 on with sporadic

seasons, but it is highly probable that the population

occurrences of E. somaense and M. fusca.

died out from summer to fall, based on the decreasing

There were seasonal variations in the size distribution

abundance (Fig. 4). Hypolimnetic water at station M-9of living (stained) A. “beccarii” forma 1 (Fig. 5).

showed low dissolved oxygen in summer and fall,

Small individuals (<240 µm) were commonly found in

especially in 2007 and 2008 (Fig. 2). Seasonal oxygen

December 2007 and March 2008, from December 2008

deficiency strongly affects the life history of brackish/to March 2009, and in May 2009. In contrast, the number

shallow-marine benthic foraminifera (e.g., Matsushita
31

Hiroyuki Takata・Toshiaki Irizuki・Koji Seto・Ritsuo Nomura# cm-310

onset of widening of
the southwestern channel

opening of
the northeastern channel

no data

Ammonia “beccarii”
forma 150
20
Trochammina hadai
15

10

5

0
2
Miliammina fusca
0
1
0

May
June
Jul.
Aug.
Sep.
Oct.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May
June
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
Jan.
Feb.
Mar.
Apr.
May

Elphidium somaense

2006

2007

2008

2009

2010

2011

Fig. 4 Seasonal variation of the abundance of selected four benthic foraminifera atstation M-9, the Honjo area, Lake Nakaumi.

and Kitazato, 1990). It is reasonable to suppose that thewhereas another new channel was opened in the

M-9 was affected by the seasonal oxygen deficiency in2009. As a result, the circulation pattern of the lagoon

decreasing abundance of A. “beccarii” forma 1 at station

northeast part (through the Moriyama Dike) in May

summer and fall.

water in the Honjo area was also altered, as shown in

Nomura and Seto (2004) reported living (stained)

our water-profile data (Fig. 2). In general, A. “beccarii”

A. “beccarii” forma 1 and T. hadai associated withforma 1 had occupied western Lake Nakaumi whereas T.

organic matter aggregates in plankton-tow samples fromhadai had occupied the eastern part (Nomura, 2003; Fig.

substantially less abundant compared to the precedingin 2007–2008 can probably explain the dispersal of A.

Lake Nakaumi. In 2010, A. “beccarii” forma 1 became1). The widening and deepening of the southwest channel

two years. Instead, T. hadai became dominant at station“beccarii” forma 1 from western Lake Nakaumi andM-9. These observations imply that the population of

its abundant settlement at station M-9 (Figs. 4 & 5). In

A. “beccarii” forma 1 was largely maintained by theaddition, M. fusca was also found at station M-9 from thedispersal of young individuals from other areas rather

2007 summer with A. “beccarii” forma 1. Because thisthan by in situ reproduction in the Honjo area during our

species was reported as a tolerant species to oligohaline

study period.

water in the Lake Shinji-Nakaumi system (Seto et al.,

In Lake Nakaumi, the channel in the southwestern

2000), it is reasonable to suppose that M. fusca alsopart of the Honjo area (around the Ohmisaki Dike) was

migrated through the southwest channel.

widened and excavated by construction in 2007–2008,

The northeast channel, in contrast, was opened in May

32

Figure5_takata
Double-column width
Response of benthic foraminifera (Rhizaria) to anthropogenic environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera
40
20
0
40
20
0
40
20
0
40
20

May 07n=10Aug. 07n=1

Oct. 07
n=23

Nov. 07
n=4

0
40
20
0
40
20
0
40
20

Dec. 07
n=205

Mar. 08
n=75

Apr. 08
n=34

0
40
20
0

0

40

June 08
n=35

20
0
40

Jul. 08
n=49

20
0
40

Aug. 08
n=35

20
0
40

Sep. 08n=27

20

Oct. 08n=16

20

Nov. 08
n=30

20

20
0
40
20
0
40
20

20

20
0
40

0
40

Dec. 08
n=136

20

20
0
40

Jan. 09
n=243

40
0

0
40

0
40

0
40

120 240 360 480 600 0
Test diameter (μm)

20Mar. 09
n=128

Apr. 09
n=95

May 09n=127

June 09
n=34

0
40

0
40

0
80

May 08
n=54

40

20
0

120 240 360 480 600 0
Test diameter (μm)

Jul. 09n=115

Aug. 09
n=138

Sep. 09
n=103

Nov. 09n=85

120 240 360 480 600
Test diameter (μm)

Fig. 5 Seasonal variations of the size distribution of living (stained) Ammonia “beccarii” forma 1 at station

M-9, the Honjo area, Lake Nakaumi. The perfect (unbroken) and broken tests were shown using open andfilled boxes, respectively.

33

Hiroyuki Takata・Toshiaki Irizuki・Koji Seto・Ritsuo Nomura
40

40Feb. 10
n=8

20
0
40

20
0
40

Apr. 10
n=2

20
0
40

0
40

0
40

0
40

0
40

0
40

0
40

0
40

Oct. 10
n=2

20
0
40

Nov. 10n=60

0

120 240 360 480 600
Test diameter (μm)

broken test
unbroken test20
0

May 11
n=1

20
0

0
40

Apr. 11n=18

20Aug. 10n=220Mar. 11n=37

20

July. 10n=1

20Feb. 11n=14

20

June 10n=7

20Jan. 11n=620

May 10n=520

Dec. 10n=21

120 240 360 480 600
Test diameter (μm)

Fig. 5 Continued.

34

Response of benthic foraminifera (Rhizaria) to anthropogenic environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera

2009, prior to the increase of T. hadai at station M-9role in the dispersal of some benthic foraminifera in(224Ra/228Ra) of the lagoon waters in 2011 indicated adue to the intense seasonal northwesterly winds in winterbeginning in early 2010 (Fig. 4). Radium isotope data

Maizuru Bay, central Japan. Thus, water-column mixing

westward inflow of the hypolimnetic water from Lakemight also be important dispersal mechanism of benthic

Nakaumi into the Honjo area through the northeast

foraminifera in Lake Nakaumi in general and in thechannel (Nomura et al., 2015). Although a detailed

Honjo area specifically.

discussion of foraminiferal transitions should include theAlve (1999) discussed the colonization processes ofpossible influence of other environmental factors, it isbenthic foraminifera. Subsequently, Weinmann (2018)

channel led to the dominance of T. hadai, which probably

for benthic foraminifera: (1) propagule dispersal andreasonable to suppose that the opening of the northeast

proposed two classes of possible dispersal mechanisms

migrated from eastern Lake Nakaumi through this(2) passive dispersal. These two mechanisms were alsochannel. In addition, E. somaense is commonly founddescribed by Alve (1999), as the “release and transport

in the Sakai Channel (Nomura and Seto, 1992), and itsof embryonic juveniles” and the “passive suspension andfirst appearance at station M-9 (Fig. 4) in the 2009/2010

transport of various growth stages,” respectively. Takata

winter supports the dispersal of benthic foraminifera

et al. (2019) stressed the importance of passive dispersal

from eastern Lake Nakaumi to the Honjo area throughof benthic foraminifera on floating of organic matterthe northeast channel after its opening. Thus, theaggregates in Lake Nakaumi, referring to Nomura andconstruction of the two channels could explain the faunal

Seto (2004) and Nomura et al. (2010). Further biologicaltransition of benthic foraminifera in our study, especiallymonitoring of benthic foraminifera and observations of

the change of the dominant species from A. “beccarii”

meiobenthic samples from other fixed stations duringforma 1 to T. hadai, through a shift of the provenancethe same period in Lake Nakaumi and the Honjo areaof the individuals supplied from Lake Nakaumi. This

would provide a useful opportunity for studying the

scenario also would explain marked decreasing in 2009dispersal mechanisms of neritic benthic foraminifera

and the subsequent few occurrences of A. “beccarii”

under natural conditions. In addition, our results forforma 1 at station M-9, in spite of improvement of thebenthic foraminifera, in combination with those for theoxygen deficiency in summer and fall (Fig. 2).

macrobenthos and ostracods (e.g., Kurata et al., 2018),

In the 2007/2008 and 2008/2009 winters, A. “beccarii”

will be useful for further understanding of biologicalforma 1 was abundant and M. fusca was common

monitoring results in Lake Nakaumi and the Honjo area.

(Fig. 4). In addition, E. somaense was present in the
2009/2010 winter (Fig. 4). In particular, occurrences

Acknowledgementsof M. fusca and E. somaense were common just after

periods of relatively strong northwesterly winds (Japan

We thank Dr. Kota Katsuki, Mrs. Kouki Noda, Hiroki

Meteorological Agency: http://www.data.jma.go.jp/gmd/

Ogusa and Takayuki Yokose and Ms. Kaori Matsumotos ) and November 2009 (11.2 m s ), respectively (Figs.

field surveys. We are indebted to Dr. Yoshiki Saito

risk/obsdl/index.php) in December 2008 (7.4 and 7.8 m–1(Shimane University) for their assistance during the–1

2 & 4). The dispersal of these three species in winter(Guest editor) and two anonymous reviewers for theirmight be stimulated by water-column mixing associatedconstructive comments. This study was partly supportedwith the seasonal northwesterly winds of the East Asianby grants from the Research Project Promotion Institute,winter monsoon. Suzuki et al. (2019) reported a positive

Shimane University.

relationship between the abundance of temperate sea bass
(Lateplabrax japonicus) in Tango Bay, central Japan,

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and Taxonomy of Agglutinated Foraminifera, (eds.)

Sampei, Y., Matsumoto, E., Kamei, T. and Tokuoka,

D.B., pp. 695–715, Kluwer Academic Publishers,

sediments from coastal brackish lakes in the Shimane

Hemleben, C., Kaminski, M.A., Kuhnt, W. and Scott,T. (1997) Sulfur and organic carbon relationship in

Netherlands.

peninsula district, southwest Japan. Geochemical

Nomura, R. (2003) assessing the roles of artificial vs.

Journal, 31: 245–262.

natural impacts on brackish lake environments:

Seto, K., Masaki, O., Tanaka, K. and Takayasu, K. (2000)

Japan. The Journal of the Geological Society of Japan,

Geoscience Reports of Shimane University, 19: 65–76.

foraminiferal evidence from Lake Nakaumi, southwest

Benthic foraminiferal assemblage in the Lake Shinji.

109: 197–214.

(in Japanese with English abstract)

Nomura, R. and Seto, K. (1992) Benthic foraminifera

Suzuki K. W., Fuji, T., Kasai, A., Itoh, S., Kimura, S.

southwestern Honshu, Japan. In: Centenary of Japanese

the transport of Japanese temperate bass Lateolabrax

from brack ish La ke Na kaum i, San-in distr ict,and Yamashita, Y. (2019) Winter monsoon promotes

Micropaleontology, (eds.) Ishizaki, K. and Saito, T., pp.

japonicus eggs and larvae toward the innermost part of

227–240, Terra Scientific Publishing Company, Tokyo.

Tango Bay, the Sea of Japan. Fisheries Oceanography,

Nomura, R. and Seto, K. (2002) Influence of man-made29: 66-83 doi: 10.1111/fog.12450.

construction on environmental conditions in brackish

Takata, H., Nomura, R., Sampei, Y., Tanaka, S. and Khim,evidence. The Journal of the Geological Society offoraminifera in the coastal areas of the Japanese

Lake Nakaumi, southwest Japan: Foraminiferal

B.-K. (2019) Dispersal potential of neritic benthic

Japan, 108: 339–409.

Islands and its application to paleoenvironmental

Nomura, R. and Seto, K. (2004) Water conditions during

studies. Estuarine, Costal and Shelf Science, 227:

the time of red tide occurrence in spring, 2003, and106288.

the associated benthic foraminifera in Lake Nakaumi.

Weinmann, A.E. (2018) Distribution and dispersal of

LAGUNA, 11: 125–130. (in Japanese with English

foraminifera in times of global changes. Abstract

abstract)

volume of FORAMS 2018, 680.

Nomura, R., Seto, K. and Tsujimoto, A. (2010) High36

Response of benthic foraminifera (Rhizaria) to anthropogenic environmental changes in the Honjo area of
Lake Nakaumi (southwestern Japan): dispersal potential of neritic benthic foraminifera

Appedix Occurrences of living (stained) benthic foraminifera at statin M-9, the Honjo area, Lake Nakaumi; shaded

samples were not observed in this study; “split” shows the number of splitting of the samples for our observation. Table 1_takata
Double-column width

Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total

2006
May, 22

Jun, 26

Jul, 22

Aug, 23

Sep, 26

Oct, 20

Dec, 5

1

24

1

25
1

0
2

0
1

0
1

0
1

1
1

-

Jan, 30

Feb, 26

Mar, 26

Apr, 23

May, 21Jun, 20

Jul, 21

Aug, 20

Sep, 18

Oct, 21

Nov, 24

Dec, 20

2007

1

25

10

17

8

1

15

23

4

205

8
1

1
2

15
1

23
2

4
2

Table 1_takata
205
2
Double-column
widthJul, 20

Aug, 17

Sep, 18

Oct, 22

Nov, 22

Dec, 24

1

2

19

-

-

0
2

25
4

11
2

17
1

Jan, 26

Feb, 19

Mar, 18

Apr, 20

May, 17Jun, 26

2008

1

3

3

1

75

34

54

35

40

35

27

16

30

137

43
4

35
4

27
4

17
4

32
4

156
4

Jul, 27

Aug, 25

Sep, 25

Oct, 22

Nov, 20

Dec, 24

9

1
3

-

-

76
4

34
4

58
4

35
4

Jan, 20

Feb, 22

Mar, 21

Apr, 27

May, 21

Jul, 2

44

8

21

2009

42

1

1

5

2

3

4

3
6

3
243

129

95

127

34

115

138

37

285

-

174

103

153

103

113

1

34

117

141

109

84
2
1
3

122

94

44
8
1
10
75

Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Continued.
Appedix
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split
Year
Date
Ammobaculites exiguus
Lagenammina sp.
Miliammina fusca
Textularia earlandi
Trochammina hadai
Trochammina pacifica
Quinqueloculia lamarckiana
Miliolinella circularis
Cyclogyra planorbis
Ammonia "beccarii" forma 1
Ammonia "beccarii" forma 2
Ammonia sp. A
Buliminella elegantissima
Elphidium somaense
Rosalina cf. bradyi
Total
Split

75

34

54

35

40

35

27

16

30

137

Hiroyuki Takata・Toshiaki Irizuki・Koji Seto・Ritsuo Nomura
-

-

76
4

34
4

58
4

35
4

Jan, 20

Feb, 22

Mar, 21

Apr, 27

May, 21

Jul, 2

44

8

21

43
4

35
4

27
4

17
4

32
4

156
4

Jul, 27

Aug, 25

Sep, 25

Oct, 22

Nov, 20

Dec, 24

9

1
3

2009

42

1

1

5

2

3

4

3
6

3
243

129

95

127

34

115

138

103

113

1

285
4

-

174
4

103
4

153
4

34
4

Jan, 24

Feb, 23

Mar, 22

Apr, 24

May, 20

Jun, 30

1

1

1

30

82
1

129

84
2
1
3

44
8
1
10

94
75Table 1_takata
4Double-column
4
width

117
4

141
4

109
4

122
4

Jul, 21

Aug, 23

Sep, 30

Oct, 20

Nov, 20

1

1

41

2
96

42

45

99

2

6

1

1

22
1

46
8

1
54
8

2010

12
26

1
30

3
31
5

8

1
1

1

2

1
225

3
1
5
1

7

1

3
80
4

40
4

Jan, 20

Feb, 20

33
4

86
8

137
4

Apr, 20

May, 212011
Mar, 201

1

17

Dec, 20
1
2

18

72

71

53

79

6

14

37

19

1

25
8

86
8

108
8

73
8

80
8

38

233
8

42
8

2

1
104
8

17
8

1
126
8