The impact of a Gyrodinium aureolum bloom on inshore young fish populations

Blooms of the dinoflagellate, Gyrodinium aureolum have been recorded on the coasts of Europe and are fully reviewed by Tangen (1977) and Boalch (1979). The significance of these blooms is considerable, and with the increase in the eutrophication of inshore waters they are now an important factor influencing the ecology of coastal waters (Boalch, 1984). Their numbers increase to concentrations in excess of five million cells per litre during warm, stable conditions resulting in the waters becoming a greenish-brown colour, ‘slimy’ and with a characteristic smell (Boalch, 1979; Jenkinson, 1986). At these concentrations there are reports that local fauna may be adversely affected and certain species will die.