Research Product

The occurrence, prevalence, seasonality and histopathological progression of a cellular disorder, thought to be a haemic neoplasm, were studied in subpopulations of Mytilus edulis inhabiting different sites in Yaquina Bay, Oregon, from 1976-1981. There were significant differences in the occurrence of the disorder that were related to geographical location. In the subpopulation with the highest levels of the disease, the prevalence rates ranged from 0 to 20% with a 5-year mean of 9.8%. There was a statisticially significant relationship between prevalence and season. During the 5-year study period, there was a consistent pattern characterized by highest prevalences during January to March followed by a period of decline to lower levels during the summer and early autumn, after which there was an increase. Data analyses revealed that there was no seasonal histopathological progression of the disorder. Numbers of stage 1 (early), 2, 3 and 4 (advanced) cases were not related to season but occurred in a random manner throughout the entire year.