Dynamic surveys for TCBS and EMB group bacteria within the Zhujiang River Estuary,South China Sea during 1999~2002

Dynamic surveys for TCBS and EMB group bacteria among 26 observation stations within the Zhujiang River Estuary, South China Sea (21°50'~22°50'N,113°20'~114°50'E) were conducted during 1999~2002, and the results are as follows:(1) TCBS group includes 37% Ⅰ (Pseudomonas, Aeromonas), 5% Ⅱ (Vibrio parahemolyticus) and 58% Ⅲ (Vibriocholerae, Vibrio cholerae biotype EI-Tor, Vibrioal ginolyticus).EMB group includes 14% Ⅳ(Proteus, Salmonella, and Shigella), 50% Ⅴ(Enter-obacter, Klebsiella, Hafnia, Sarratia), and 36% Ⅵ (Escherichia coli).(2) The values of annualmean CFU/mm³ among the 26 stations are significantly different.Each station has more TCBS group than EMB group, indicating that TCBS group becomes native dominant whereas EMB group mainly comes from land-originated pollutions.(3) The 26 stations are clustered into four subclusters with no coincidence with their reallinkages of geolocations, suggesting that the interference effects by human activities are dominant over those by natural geoisolations.Station G (Wanshan Islands) and Sta.H (Dangan Island) are the farthestisolated islands, but are clustered into two different subclusters.Station H has the highest value of TCBS group[(3.7±2.6×10⁴CFU/cm³)]whereas Sta.Gas a natural farming area has the highest value of EMB group[(9.5±6.6×10³CFU/cm³], indicating that farming activities produced pollutions dramatically.(4) The values of monthly mean CFU/cm³ among TCBS and EMB group show similar variations annually and seasonally.(5) The Zhujiang River Estuary is further divided into south and north parts.The south part is heavily polluted by the land-originated EMB group bacteria, reflecting the high-through-put contaminations from the network of the Zhujiang River, the self-produced pollutions from costal farming areas, and the amplification in situ of all pollutions through farming activities.