Bacterial and parasitic contamination in blood cockles (Anadara antiquata Linnaeus, 1758), and effect of depuration on bacterial load using simple bio-filter in closed circulatory system

Blood cockle (Anadara antiquata Linnaeus, 1758) serves as a vital food and protein source for many coastal communities in Fiji. However, no studies have been conducted on bacterial and parasitic contamination in blood cockles in Fiji, leaving a significant knowledge gap. The present work thus aimed to determine the presence, types, and prevalence of parasites in blood cockles across four sites in Fiji, as well as to evaluate the effectiveness of depuration in reducing bacterial loads using a closed circulatory system with a simple biofilter. Blood cockles were collected from Nasese Coast, Viwa Island, Bau Landing, and Tailevu in the Central Division of Viti Levu, Fiji. Ectoparasites were observed on the shell surface, while endoparasites were identified in the digestive tract, gills, and muscles. The depuration system’s effect on bacterial loads, including total plate count (TPC), coliforms, and Vibrio spp., was monitored over 48 h. Both endoparasites and ectoparasites were detected, with a mean prevalence of 29.3% at Nasese Coast, 0% at Viwa Island, 4% at Bau Landing, and 6.7% at Nasilai Coast. In tanks maintained at room temperature, bacterial contamination in blood cockles decreased to undetectable levels within 48 h of depuration. However, in tanks with elevated temperatures, TPC, coliforms, and Vibrio spp. increased by 48 h, resulting in 100% mortality of the blood cockles. The present work demonstrated that room-temperature depuration with a simple biofilter could be an effective and economical method for improving food safety and reducing health risks associated with consuming blood cockles.