EFFECTS OF STOCK AND CULTURE ENVIRONMENT ON INFECTIONS BY MARTEILIA-REFRINGENS AND MYTILICOLA-INTESTINALIS IN THE MUSSEL MYTILUS-GALLOPROVINCIALIS CULTURED IN GALICIA (NW SPAIN)

The effects of stock and culture environment on the prevalence of Mart eilia refringens and Mytilicola intestinalis in the mussel Mytilus gal loprovincialis, cultured in the Ria de Arousa (Galicia, NW Spain) were studied in a transplantation experiment. Mussel seed from 4 natural p opulations (stocks) of the Galician coast were transferred to culture ropes hung from the fore-part and aft-part (situations) of rafts locat ed in 3 culture areas (sites) inside the ria. The prevalence of M. ref ringens was mainly affected by the culture site. Thus, mussels cultiva ted in the inner area of the ria showed significantly higher prevalenc es than those in the middle and outer ones. Stock and situation within the raft showed less important effects. None of the 3 factors investi gated showed important effects on the prevalence of M. intestinalis.