This is the first record of the copepod Pseudomyicola spinosus in the scallop Argopecten ventricosus in northwestern Mexico, and describes: (1) the known annual prevalence and intensity of this copepod on scallops from culture sites (Gulf of California) and natural populations (Pacific coast), (2) the histopathological effects caused on the soft tissues of scallops, and (3) the relationship between prevalence and intensity records and environmental parameters. The copepod was present throughout the period of investigation, showing similar prevalence and ratio of copepod to scallop patterns in both cultured scallops and wild specimens from natural habitats. Highest prevalence and ratio values were detected in summer-autumn at both sites, probably because scallops showed a weak condition from the combined effects of spawning, reabsorption of residual gametes, and high temperature. The condition index of A. ventricosus showed a significant correlation with the presence of the copepod in Magdalena Bay (-0.67). P. spinosus was observed in the gills of scallops, producing alterations or rupture of filaments, and in the stomach, causing detachment and loss of the epithelium. No relationship between copepod infestation with temperature, salinity, chlorophyll, and seston were found during the investigation. Although P. spinosus was present year-round at both sites, no association between infestation and scallop mortalities was detected.
Animals Bivalvia