BACTERIOLOGICAL STUDIES ON MUSSELS AND OYSTERS FROM 6 RIVER SYSTEMS IN PRINCE-EDWARD-ISLAND, CANADA

Eighty-five blue mussels and 46 eastern oysters were collected from sh ellfish growing areas of 6 river systems in Prince Edward Island, and examined for aerobic and anaerobic bacterial flora. Animals were colle cted in different seasons during a 14-month period. Of a total of 907 isolates recovered, 76% were aerobes, and 24% were anaerobes. Isolatio n rates of 572 aerobes grouped by genera were compared, with respect t o sites of sampling and seasons. Vibrio was the most frequently isolat ed genus from animals originating from all river systems, except musse ls collected from Cardigan River, which had Staphylococcus as the pred ominant flora. Mussels collected during winter yielded a higher percen tage of Staphylococcus spp., while animals collected during other seas ons had Vibrio as the major genus. Among 51 Vibrio isolates speciated with the aid of commercial identification systems, the most common spe cies were Vibrio (Listonella) anguillarum from oysters, and V. alginol yticus and V. splendidus from mussels. Vibrio parahaemolyticus was iso lated from 5% of animals. The most common Staphylococcus species was S . capitis subspecies ureolyticus. Among anaerobes Clostridium perfring ens was the major species among identified isolates.