京都大学防災研究所年報 第 56 号 B 平成 25 年 6 月
Annuals of Disas. Prev. Res. Inst., Kyoto Univ., No. 56 B, 2013

Influence of Point Environmental Conditions to the PresentSpecies Richness of Fish and Mussel of Floodplain Pools in the Kizu River
Mikyoung CHOI(1), Yasuhiro TAKEMON, Kinko IKEDA(2), Kazuhiro NISHII(2) andTetsuya SUMI
(1) Graduate School of Engineering, Kyoto University(2) ASIA AIR SURVEY CO., LTD.
Synopsis
The Kizu River ecosystem is characterized by lentic habitats such as pools or wando
on the floodplain, providing habitats to Acheilognathus bitterlings and freshwater
unionid mussels. In the last decade, however, these habitats have been degraded by thedecrease of peak discharge and flood frequency and excessive vegetation expansion on
the floodplain. In order to restore the suitable habitat structure for the Kizu Riverecosystem, it is needed to find out relations of habitat condition required for bitterlings
and mussels. We used principal component analysis (PCA) and generalized linear model(GLM) based on selected data by correlation analysis. Species richness of Bitterling wasbest explained by a model consist of location, age, transparency, mean grain size andDO one year ago. Species richness of mussel was best explained by a model consist offlooding frequency and depth of mud two years ago. Species richness of resident fish
was best explained by low relative height, age, area and vegetation coverage, andspecies richness of alien fish was explained by model consist of low relative, area,vegetation coverage and DO. Species richness of resident fish and alien fish weresignificantly correlated with habitat conditions of current year. The results indicate arange of habitat age for maintenance of fish and mussel diversity including more than
two years old, is required in the Kizu River.
Keywords: bitterling, mussel, alien fish, species richness, habitat conditions

1.

Introduction

The Kizu River has been known lentic habitat
such as pool or wando for bitterlings and unionid
mussels living in lentic habitats on its’ floodplain(ASIA AIR SURVEY, 2009). In the last decade,however, these habitats have been degraded by thedecrease of peak discharge and flood frequency andexcessive vegetation expansion on the floodplain(Ashida et al, 2008). According to the deteriorationof habitat condition, the diversity of bitterling andbivalve decreased, and representative protected

bitterling‘Acheilognathus
longipinnis’
haddisappeared in the Kizu River (Kizu River ResearchGroup, 2003). To restore the habitat structure ofspecies diversity, especially bitterling and mussel, it
is needed to find out relations of habitat condition
required for bitterlings and mussels. In other tounderstand the intrinsic reasons for their presenceor absence in a pool, it is inevitably important toanalyze effects of habitat conditions not only atpresent but also in the past.The survival of mussels
depends on the interaction of several biotic andabiotic factors operating at different spatial and― 713 ―temporal scales (Morales et al., 2006; Haag andWarren, 1998). Because successful reproduction
requires the availability of an appropriate host fishat the appropriate time and that juveniles findfavorable habitat, mussels had possibility that they
were related with spatial diversity as well as timelag. However, there have been only a few works
showed empirical interrelations of species richness
in a particular habitat to its environmental
conditions (Negish et al., 2012; Strayer and Ralley,
1993; Yoshihiro and Takashi, 2010; Holland-Bartels, 1990; Layzer and Madison, 1995).
This paper aims to clarify the amount of timelag between habitat changes having a significant
influence on species diversity and bitterling andunionid mussel. In addition, we attempted to figureout habitat parameters having a dominant role onspecies diversity.

Figure 1 The study site of the Kizu River

2.

Method

2.1 Study site
The study area was established in the lower
reaches (0~32 km) of the Kizu River, a tributary ofthe Yodo River in central Japan (Fig.1). A mean ofriver slope in study area was 1/1180 and mean
diameter of bed material was 2 mm ~3 mm (KizuRiver Research Group, 2009). The study area wascomposed of bareland (ca. 21%), bushland (ca.
42%), woodland (ca. 14 %) on the floodplain, andwater surface (ca. 23%). Vegetation area on thefloodplain increased about 8 times and barelandarea decreased about 70% compare with in 1948
(Choi et al, 2012).
2.2 Materials(1) Fish and bivalve data (response variable)
We used species and habitat condition data from
ASIA AIR SURVEY CO., LTD. A total of 47
floodplain pools surveyed from 10 to 26 August
2011. Fish and mussel data were classified into
bitterling, unionid mussel, resident fish except
bitterling, and predatory alien fish (e.g. bass, bluegill, snake head). Because successful reproductionof mussels requires the availability of an
appropriate host fish (Morales et al., 2006; Haagand Warren, 1998), and exotic species and degradedwater quality influenced declines of fish (Lydeardet al.,2004), we considered resident fish andpredator fish as well as bitterling and mussel. The
species richness of four groups was used as
response variables to detect relations of fish andmussel diversity to habitat conditions.
(2) Habitat condition data (explanatory variable)
Following parameters measured by the fieldsurveys were used for the analyses: habitat size,area of water surface, water depth, area of water
depth than low 30 cm, transparency of water, water
quality (PH, DO, COD, SS, EC, ORP), Chlorophyll,
vegetation coverage, ratio of floating plants, grain
size (mean, D60, D50, D30), depth of mud, porosity
and ignition loss, relative height (low, mean, high),flooding frequency, age and location. Relative
height is height between water level of main
channel and level of 5 m buffer around pool.
Flooding frequency was calculated by simulation
using DEM data and water discharge of 10 years (0:no flooding, 1: one time, 2: eight times, 3: 16 times,
4: 22 times, 5: normally flooding per 1 year) . Ageof pool defined by existent period of habitat using
aerial photo from 2001 to 2012, and location was
section number (0 ~ 32). A total of 27 habitat
condition parameters
were considered as
explanatory variables. Relations of current species
diversity to current habitat conditions as well as
past conditions were analyzed using data of habitat
conditions in 2007, 2009, 2010 and 2011.
2.3 Data analysis
To select representative explanatory variables
among many habitat conditions, we used correlation
analysis and principal component analysis (PCA).
Correlation analysis was conducted for picking out
data of habitat conditions statistically. And then,― 714 ―final explanatory variables were selected by PCA.
Relations of fish and bivalve diversity to habitat
conditions were analyzed using generalized linear
model (GLM) with a Poisson error assumption anda long link function. Values of area and depth as
explanatory data were log transformed, because
they did not show normal distribution. The bestmodel was selected based on Akaike’s Information
Criterion (AIC; Akaike, 1974), and Chi-squared (χ²)
was used to compare effect of past and recent
conditions on fish and bivalve diversity. Allanalyses were conducted using SPSS version 19(SPSS 19.0, SPSS Inc).
3.

Results and discussion

Final explanatory variables were selected into
low relative height, flooding frequency, age,location, habitat size, water quality (PH, DO),transparency, vegetation coverage, mean grain size,and depth of mud. Species richness of bitterling wasbest explained by a model consist of location, age,transparency, mean grain size and DO one year ago(χ² = 3.83, P = 0.05). Species richness of mussel

Table 1was best explained by a model consist of flooding
frequency and depth of mud two years ago (χ² =12.18, P <0.001). This result showed species
richness of mussel was influenced by habitat
conditions 2years ago. It may assume that mussels
were reproduced or flowed from main channel inthe past. Because freshwater unionid mussel was
taken about 5 years from reproduction toadulthood(Mahon and Bogan, 2001), a time lag may
exist between current species richness and past
habitat conditions. In addition, they required
appropriate substrate to anchor and burrow, andsubstrate stability may affect their distribution(Holland-Bartels, 1990; Layzer and Madison, 1995;
McRae et al, 2004).Species richness of resident fish
was best explained by low relative height, age, areaand vegetation coverage (χ² = 18.34, P <0.001) andspecies richness of alien fish were explained bymodel consist of low relative, area, vegetation
coverage and DO (χ² = 20.42, P <0.001). Species
richness of resident fish and alien fish weresignificatly related to habitat conditions of current
year (Table 1).
Species richness of bittering had no significant

Results of generalized linear model tested the relations of species richness in 2011 and habitat
conditions in 2007, 2009, 2010 and 2011.

Species ofrichness
Bitterling

Model
Statistic datanYear

Wald χ²p-value

52011
2010
2009
2007

1.81
3.83
1.84
3.15

.177.050.174.076

Field survey data

Location + age Transparency + mean grain
size + DO

MusselFlooding
frequency

Depth of mud

22011
2010
2009
2007

0.56
1.99
12.18
5.90.454.157.000.015

Resident fish

Low relative
height + age

Area + vegetation coverage

42011
2010
2009
2007

18.34
2.14
1.13
0.75.000.143.287.386

Alien fish

Low relative
heightArea + vegetation coverage
+ DO4

2011

20.42.000

2010

0.28.594

2009

0.59.441

2007

0.55.456― 715 ―

correlations separately. Although they did not showcorrelation between bitterling diversity in 2011 andeach habitat condition in 2010 (Table 2), Figure 3
showed species richness of bitterling increased withhigh habitat age. For the preservation of symbiosis
between bitterlings and mussels, a stabilized
environment as well as immediate disturbance forboth animals required. Species richness of mussel
positively correlated with depth of mud (R = -0.524,P < 0.5) (Table 1). Although they had negative
correlation, also had low R2value, species richnessof mussel had maximized results between 5 ~10 cm.
Hence, mussel diversity required some disturbanceto maintain depth of mud between 5~10 cm (Fig. 2).
Therefore, to determine a target of substratecondition for mussel diversity, we should consider
the effect of past conditions as well as current
conditions.
Species richness of resident fish had a negative
correlations with low relative height (R = -0.394, P< 0.5) and vegetation coverage (R = -0.35, P < 0.5).
Species richness of alien fish showed a negative
correlation with vegetation coverage (R = -0.341, P< 0.5) and a positive correlation with habitat size (R= .547, P < 0.5) and DO (R = 0.438, P < 0.5) (Table2). As Jacqueline (1989), predators such as bassprefer the heavily vegetated sites and open areas.
Our study also showed species richness of alien fish
had a possive correlation with habitat size.
However, they were negativly correlated withvegetation coverage. They had maximum values
between 10~20 % vegetation coverage in the Kizu
River.

Figure 2 Relation of species richness of mussel
in 2011 to depth of mud in 2009. p<0.05

Figure 3 Relation of species richness ofbitterling in 2011 to habitat age in 2010. n.s.

Figure 4 Relation of species richness of alienfish to vegetation coverage in 2011. p<0.05

Table 2 Results of correlation analysis tested relations between species richness and habitat conditions
were used in model. Relations between bitterling richness in 2011 and habitat conditions in 2010.
Relations between mussel richness in 2011 and habitat conditions in 2009, and relations between fishrichness in 2011 and habitat conditions in 2011. (r values. *** p<0.001, * *p<0.01, * p<0.05)
Species ofrichness

Lowlocation Floodin

area

Vegetati

relativegonheightfrequenc

coveragye

Bitterling
MusselResident fish
Alien fish

age

.220

.331

DO-.287

Mean

Depth

ency

grain

of mudsize-.203-.454-.394 **-.288transpar-.151-.007-.524 *

.324 *.547***― 716 ―-.350 *-.341 *.438**

4.

Conclusion

We used correlation analysis, principal
component analysis (PCA) and generalized linear
model (GLM) to find out relations of habitat
condition required for bitterlings and mussels .
Species richness of bitterling was best explained bya model consist of location, age, transparency,
mean grain size and DO one year ago. Species
richness of Unionid mussel was best explained by amodel consist of flooding frequency and depth of
mud two years ago. Species richness of resident fish
was best explained by low relative height, age, areaand vegetation coverage, and species richness ofalien fish was explained by model consist of low
relative, area, vegetation coverage and DO. Species
richness of resident fish and alien fish weresignificatly relatived to habitat conditions of current
year (Table 1). Range of habitat age formaintenance of fish and mussel diversity including
more than two years old, is required in the Kizu
River. To maintain a healthy and sustainable habitat
for fishes and mussels, a wide range of habitat age
should be considered.
Acknowledgements
This study was conducted in a research project“Development of riverbed management techniquesfor river environments” supported by the Japanese
Ministry of Land, infrastructure, Transport andTourism. We would like to the Yodo River Bureau
for providing aerial photo and DEM dataReferences
ASIA AIR SURVEY CO., LTD (2009) Report ofpond research in the Kizu River, part 2
Ashida K., Egashira S. and Nakagawa H. (2008)
River Morphodynamics for the 21 st Century,
Kyoto University Press, pp 40-51
Akaike H. (1974) A new look at the statisticalmodel identification, IEE Automat Contr. Vol 19,
pp 716-723
Choi M., Takemon Y. and Sumi T. ( 2012) TheHistorical Changes of Aquatic Habitat Structure inthe Kizu River, 18 th Congress of the Asia andPacific Division of the International Associationfor Hydro-Environment Engineering and Research,
SS4F-2
Gangloff M.M. and Feminella J.W. (2007) Streamchannel geomorpholpgy influences mussel
abundance in southern Appalachian streams,U.S.A., Freshwater Biology, Vol 52, pp 64-74
Haag W.R. and Warren M.L. (1998) Role ofecological factors and reproductive strategies instructuring freshwater mussel communities,
Canadian Journal of Fisheries and AquaticSciences, Vol. 55, pp297-306
Holland-Bartels L.E. (1990) Physical factors andtheir influence on the mussel fauna of a main
channel border habitat of the Upper Mississippi
River, Journal of the North American
Benthological Society Vol. 9, pp 327-335
Layer J.B. and L.M. Madison (1995) Microhabitat
use by freshwater mussels and recommendations
for determining their instream flow needs,
Regulated Rivers: Research and Management Vol.
10, pp 329-345
Jacqueline F. S. and Roy A.S. (1989) Behavior offish predators and their prey: habitat choice
between open water and dense vegetation,
Environmental Biology of Fishes, Vol 24, pp287-293
Kizu River Research Group, 2003. Integrated
research of the Kizu River II, 442pp
MacMahon R.F. and Bogan A.E. (2001) Mollusca:
Bivalvia. pp 331-429 in H. Thorp and A.P. Covich(editors), Ecology and classification of North
American freshwater invertebrates. 2 nd edition,
Academic Press, San Diego, Califirnia.
MacRae S.E., J.D. Allan and J.B. Burch (2004)
Reach and catchment-scale determinants of thedistribution of freshwater mussels (Bivalvia:Unionidae) in south-eastern Michigan, U.S.A.
Freshwater Biology Vol. 49, pp 127-142
Mills S.C. and Reynolds J.D. (2003) The bitterling–mussel interaction as a test case for co-evolution,
Jour. Fish Biology, Vol 63, pp84-104
Morales Y., Weber L.J., Mynett A.E. and Newton
T.J.(2006) Effects of substrate and hydrodynamic
conditions on the formation of mussel beds in allarge river, J.N. Am. Benthol. Soc., Vol 25, pp664-676
Negish J. N., Sagawa S., Kayaba Y., Sanada S.,
Kume M. and Miyashita T. (2012) Mussel― 717 ―

responses to flood pulse frequency: theimportance of local habitat, Freshwater Biology
doi 10.111, j.1365-2427
Strayer D.L. and Ralley J. (1993) Microhabitat useby an assemblage of stream-dwelling unionaceans(Bivalvia), including two rare species ofAlasmidonta. Journal of the North American
Benthological Society, Vol. 12, pp 247-258
Yoshihiro B. A. and Takashi M. (2010), Habitat

characteristics influencing distribution of thefreshwater mussel Pronodularia japanensis andpotential impact on the Tokyo bittering, Tanakia
tanago, Zoological science, Vol 27, pp912-916― 718 ―

(Received June 11, 2013)