MICROHABITAT DISTRIBUTION AND COEXISTENCE OF MICROCOTYLIDAE (MONOGENEA) ON THE GILLS OF THE STRIPED MULLET MUGIL CEPHALUS - CHANCE OR COMPETITION

The two monogenean species Metamicrocotyla cephalus and Microcotyle mu gilis have specific microhabitats on the gills of Mugil cephalus on wh ich they may or may not coexist. M. cephalus is found in sector 1 of t he posterior hemibranch of arch I. M. mugilis is found on the filament s of sector 5 of the posterior hemibranch of arch I. The coexistence o f these two monogenean species on the same fish does not induce a chan ge in their respective distribution, except for a marked preference of M. cephalus for the left side and of M. mugilis for the right. This 1 5-month-long study shows that when the two species of monogeneans coex ist the infection prevalence and intensity are higher than in cases of monospecific infection. The specific character of the microhabitat, t he apparent absence of interspecific competition, and the existence of positive species interactions are discussed.