ABSTRACT: Population dynamics of the oligotrich ciliates Limnostrombidium viride and Pelagostrombidium fallax were recorded in prealpine Lake Constance, Germany, from February through November 1997. Simultaneously, their flask-shaped resting cysts were collected in sediment traps. We describe for the first time the resting stages of L. viride. Motile stages and cysts of this species were restricted to April/May, with a maximum flux rate of 2 x 10⁴ cysts m^-2 d^-1. Pelagostrombidium fallax, a dominant species throughout the year, encysted in March to June and September to November. Maximum flux rates of 1.8 x 10⁵ and 2.1 x 10⁵ cysts m^-2 d^-1 were observed in spring and autumn, respectively. Mean flux rates were 4 x 10⁴ cysts m^-2 d^-1 in spring and 3 x 10⁴ cysts m^-2 d^-1 in autumn. In summer, cyst formation ceased over a period when water temperatures were >18°C close to the lake surface. Encystment of P. fallax in spring was significantly negatively correlated with chlorophyll a.

KEY WORDS: Oligotrichida · Cyst · Limnostrombidium viride · Pelagostrombidium

Published in AME Vol. 17, No. 1 (1999) on April 30
ISSN: 0948-3055. Copyright © Inter-Research, Oldendorf/Luhe, 1999