SEASONAL-CHANGES IN THE VERTICAL-DISTRIBUTION OF 5 SPECIES OF THE FAMILY BOUGAINVILLIIDAE (CNIDARIA, ANTHOMEDUSAE) AT LOUGH-HYNE, SOUTH-WEST IRELAND

Five species of the family Bougainvilliidae were studied quantitativel y over a 22 month period in Lough Hyne marine nature reserve, south-we st Ireland. The effect of a seasonal oxy-thermocline on 'their vertica l distribution was also examined. The maximum density of each species occurred between May and September. Bongainvillia britannica (15 m(-3) ) and B. principis (13 m(-3)) occupied the lower 20 m of the water col umn whereas S., ramosa (41 m(-3)), B. pyramidata (5 m(-3)) and Lizzia blondina (358 m(-3)) existed predominantly in the upper 20 m. The vert ical distribution patterns of B. britannica and B. principis were alte red by the oxy-thermocline at 25-30 m depth in the summer months of 19 93.