抄録
Distribution of two freshwater shrimps, Paratya compressa improvisa (Atyidae) and Palaemon paucidens (Palaemonidae) were studied in 301 sites (lakes and ponds) in Aomori Prefecture, northern Japan in 2017. Paratya c. improvisa and P. paucidens were recorded from 15% and 13 % of the sites surveyed, respectively, and they tended to be found in the sites in desolate areas or those under protections, where invasive alien fishes would not been present. It is suggested that high predation pressure of the introduced largemouth bass Micropterus salmoides has depressed the shrimps considerably in the wide areas of the prefecture since 1990s. A temnocephalidan Scutariella japonica (Scutariellidae) was found on P. c. improvisa from 6 sites in Aomori Prefecture.
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