Studies on ciliated protozoa in eutrophic lakes: 1. Seasonal distribution in relation to thermal stratification and hypolimnetic anoxia

An investigation into the spatial and temporal distribution of ciliate populations in a small monomictic eutrophic lake was carried out over a one-year period. A community of large cilates dominated by Loxodes striatus, L. magnus, Spirostomum teres and Frontonia leucas occurred in the deep water sediments during the period of winter mixis. These cilates vacated the sediment during summer stratification, progressively colonising the hypolimnion in phase with the upwards spread of anoxic conditions, returning once more to the sediment following destratification. The possible significance of this ciliate community is discussed.