PRIMARY PRODUCTION STUDIES DURING A GYRODINIUM CF AUREOLUM (DINOPHYCEAE) BLOOM IN THE WESTERN ENGLISH-CHANNEL

Water column production measurements were made during a bloom of the m arine dinoflagellate Gyrodinium cf. aureolum in the Western English Ch annel in July 1987. The bloom was sampled over a period of 5 d, and pr imary production was measured using the oxygen light and dark bottle m ethod and the C-14 technique. The photosynthetic quotient (PQ) varied between 1.2 and 3.7. During the period sampled, the proportion of phae opigments significantly increased (from < 5 to > 50%) and mixed layer dissolved oxygen saturation decreased from 133 to 114%. A model was us ed to determine gross water column productivity in the surface mixed l ayer on two days, and net production values were shown to be close to zero or slightly negative. Comparisons of production values are made w ith other published G. cf. aureolum bloom data.