BACTERIA SPECIES COMPOSITION AND WATER QUALITY STATUS IN HARD CLAM (Meretrix meretrix) FARMING AREAS IN THAI BINH AND THANH HOA
Abstract
The study aims to assess the status of environmental water indicators and disease agents in the hard clam (Meretrix meretrix) farming area in the provinces of Thai Binh and Thanh Hoa. Environmental water indicators such as temperature, pH, salinity, alkalinity, NH4+, NO2-, S2-, total Vibrio in water and bacteria in hard clams were analyzed from April to October in the period of 2017-2021. The result indicated that the salinity and alkalinity decreased while NH4+ increased from August to October. The concentration of NO2- and total Vibrio density increased from April to July. Two bacterial genus including Vibrio spp. and Aeromonas spp. were isolated from hard clams. Of these, Vibrio parahaemolyticus, V. alginolyticus, and V. vulnificus accounted for 35.81, 18.60, and 14.88%, respectively. High Vibrio density in water increases the risk of Vibrio spp. bacterial infection in hard clams. The factors that affected the growth rate and productivity of hard clams in Thai Binh and Thanh Hoa were alkalinity, salinity, NH4+, NO2-, total Vibrio, and Vibrio spp.