Mass occurrence of planktonic oligotrichous ciliates in a bay in southern Norway

Abstract

A reddish-brown discoloration of the surface water in Flødevigen Bay, southern Norway on May 15, 1985 was due to planktonic oligotrichous ciliates occurring in densities of 2079 cells ml ⁻¹ . Strombidium reticulatum (Leegaard, 1915) Bush, 1921 and Tintinnopsis beroidea Stein, 1867 accounted by numbers for 59.7 and 35.1% respectively. Both the build-up and decline were probably mainly due to wind-induced hydrographical conditions. No fish mortalities were reported.