Samples of surface plankton in Lake Nojiri were collected monthly from July 1988 to October 1991.
In zooplankton 26 species were found and 25 species in phytoplankton. The seasonal succession of main species was as follows.
Bosmina longirostrisobserved through the year, but dicreased in winter.
Diaphanosoma brachyrum, Bosminopsis deitersi, Daphnia galeata, Eodiaptomus japonicusand
Polyphemus pediculus appearedfrom summer to autamn, and
Thermocyclops hyalinusfrom spring to summer. On the other hand,
Kellicottia longispina, Polyarthra vulgarisand
Keratella quadratawere found from winter to spring.
Ceratium hirundinella, Melosira italics, Cyclotella comtaand
Fragilaria crotonensiswere obsreved through the year.
Asterionella formosaappeared three season except in autumn
The prevalent species were
Keratella quadratain autumn,
Ceratium hirundinellafrom spring to autumn,
Dinobryon cylindricumin spring,
Fragilaria crotonensisfrom autumn to early winter,
Melosira italicaand
Asterionella formosain winter.
In this Lake,
Uroglenainduced a fresh water red tide from June to July in 1989. but never appeared again.
Uroglena americanaobserved twice in a year from the middle of spring to the middle of summer and from the middle of autumn to winter.
抄録全体を表示