宍道湖および中海のイシマキガイの生態学的研究

概要

論文の詳細を見る
The survey was made at three points in each station using 1 m^2 quadrate. As periwinkles show positive phototaxis and inhabit on the surface of the substratum, the qaudrate method was available to measure their density even on a stone wall with many small holes. Chlorinity was determined by means of AgNO_3 and K_2CrO_4 and shown in mg per litre. There are many periwinkles along the O-hashi River amounting to 100〜130 individuals per 1m^2,and 60〜75 inidividuals were found in the west of River Tamatsukuri, but in the west of River Kimachi only less than five individuals were found. Though the substratum seems to be favourable to the inhabitation of periwinkles, none appeared in the west of Aika situated on the northern coast and also at the western coast. It seems that the above phenomena may be due to the muddy sand carried by the stream of River Hi-i, and it should be the same at Nogi where the River Nojiro flows into the Lake. In Lake Nakaumi, periwinkles are less than 42 in number at the station observed and are influenced by the high chlorinity. Judging from the laboratory experiment the upper limit of
1960-02-01