Transactions of The Japanese Society of Irrigation, Drainage and Rural Engineering
Online ISSN : 1884-7242
Print ISSN : 1882-2789
ISSN-L : 1882-2789
Influence of Habitat Environment on the Distribution of the Freshwater Unionid Mussel Inversiunio jokohamensis in Hill-bottom Valley Ditches
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2008 Volume 2008 Issue 255 Pages 309-312,a2


In order to grasp distribution characteristics of Yokohamashijiragai (Inversiunio jokohamensis), field investigation was carried out in a hill-bottom valley during the non-irrigation period (March) in Tochigi prefecture. The results obtained from the investigation were as follows: 1) the results of correlation analysis showed that the mussel density was positively correlated to the coverage of gravel, however negatively to the bottom softness, the coverage of bedrock and of silt with a significant level of p<0.01, 2) population density in the east side ditch was higher than that in the west side ditch, probably because the gravelly bottom was dominant in the former, and 3) Young and old individuals were also found in the east ditch. The above results implied that the east side ditch holds a better breeding ground due to gravel sediment. In addition, their absence in the west side ditch may be due to the drought in early autumn and the dominance of bedrock.

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