Diel vertical migration of zooplankters and fish larvae in lake Biwa

概要

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Studies using midwater trawl and plankton nets and an echo sounder in the northern part of Lake Biwa showed that zooplankters such as Eodiaptomus iaponicus ,Mesoc-yclops leuckarti,Diaphanosoma brachyurum and Daphnia longispina, gammarid of Anisogammarus annandalei, shrimp of Palaemon paucidens, and fish such as Rhinogobius brunneus, Chanogobius isaza and Plecoglossus altivelis, undergo a diel vertical migration in various seasons. D. brachyurum ahd D. longispina concentrate near the surface at night and in the 5-20m layer during the daytime. But, no clear diel vertical migration was observed in E, japonicus and M. lauckarti. The gammarid and shrimp are distributed in deep water of more than 30m depth in the daytime, but they come up to the surface layer at night. Their adults stay near the bottom during the daytime and migrate to the midwater at night. The fry and juveniles of R. brunneus and C. isaza also stayed on the bottom during the daitime and migrate to the midwater at night. The fry of P. altivelis inhabiting near the bottom during the daytime show an upward migration to the midwater at night. The boundary for those vertical migrants exists in 10-20m layer, thermocline in summer, in Lake Biwa.
三重大学水産学部の論文
1982-10-01