We aimed to clarify the microhabitat preferences of Atyidae shrimps in the middle to upper reaches of the Hiwasa R. , Kitagawatidani R. , and Mugi R. , Tokushima Prefecture, southern central Japan. Relationships between the shrimp abundance and physical environmental variables were surveyed at six sites in 2011 fall and 2012 spring by setting 5-m line transects delineated with ten consecutive 50-cm quadrats along the riverbank. The dominant shrimp species collected from the riverbanks were Caridina multidentata, Paratya compressa and Neocaridina denticulata. C. multidentata was shown to prefer loose boulder or cobble beds with interstices. When interstices were scarce, the shrimps were found inhabiting among the vegetation. P. compressa was shown to prefer vegetation and boulder or cobble bed in pools. N. denticulata tended to prefer vegetation in darker, gently-flowing areas. Our results insist that the three shrimp species segregate microhabitat under base-flow conditions, but flow reduction may cause microhabitat overlap between C. multidentata and P, compressa.

Phenolic compounds in the soils collected from plow layers of greenhouse and field cultures were surveyed quantitatively by gas chromatography. The results are as follows : 1) p-Coumaric, ferulic, salicylic, p-hydroxybenzoic, vanillic, syringic, and protocatechuic acids were detected in all upland soils, as in the case of paddy and forest soils reported previously. Among these phenolics, p-coumaric acid was present in the largest quantity in most of the upland soils up to 29.0 ppm. 2) The total amounts of individual phenolic acids in the upland soils ranged from 9.5 to 62.0 ppm (average 26.0 ppm). Also, the amounts were less than 0.18% (average 0.10%) of the total soil organic matter. The average values in the upland soils were higher than those in the paddy soils, but were lower than those in the forest soils. 3) In upland soils, the concentrations of p-hydroxybenzoic, vanillic, syringic, p-coumaric, and ferulic acids, which have no chelating ability, were considerably related to the carbon content of soil, but the concentrations of protocatechuic and salicylic acids, which are chelating agents, were not related to that of soil. These relationships agreed with those found in paddy and forest soils.