Water Quality, Bacterial Counts and Mussel Growth in Four Mussel Culture Areas in the Upper Gulf of Thailand

Abstract

Four mussel culture areas in the Upper Gulf of Thailand were monitored for 1.5 years to assess environmental pollution in terms of bacterial levels, water quality and mussel growth. Contamination with bacteria including fecal coliforms was worse in Mae Klong and Chao Phraya estuaries than Ang Sila and Bang Pakong. More serious contamination in those estuaries usually occurred during the rainy season (July-October) and at low tides. Bacterial contamination of mussels occurred 10-40% of the sampling time, whereas the culture water was contaminated 20-55% of the time. Salinity fluctuated (1-35 ppt) during the rainy season, but dissolved oxygen (3.3-9.8 mg•l·1), temperature (26-33°C) and pH (6.5-8.7) were suitable for mussel culture. Obvious eutrophication in the gulf leads to frequent algal blooms, which may have caused the occasional large-scale mussel die-offs. At the four sites, mussel growth in terms of meat weight gain was 8-26% in 1994 and 60-140% in 1995, condition factor was 97-110 (good to excellent), and density settlement was 17-59 cm·1 cross section.