Research Of Chlorophyll A And Related Water Quality And PC And McyB Gene In Fish Ponds

Cyanobacteria(blue-green algae) are common phytoplankton in eutrophic freshwater systems characterized by relatively stable water columns or long-residence times. It has been one of the worldwide concerns due to their production of a range of hepatotoxins and neurotoxins. Especially one group of these toxins, the microcystin(MC), which is an intracellular hepatotoxin synthetized in the Microcystis sp., is frequently detected in lakes, reservoirs and aquaculture ponds. Microcystis sp. is a globally concerned problem. In fish ponds, Microcystis sp., Anabaena sp. etc. which belong to cyanobacteria can cause the lower fish production. It has been a long history for people to study on microcystis. Valuable results have been made, but still many problems to be solved. Blooms of cyanobacteria frequently occur in freshwater in several areas of the world. These toxigenic cyanobacteria cause serious damage for water supplies and food safety.In this study, researched on the Chiang Mai and Chiang Mai surrounding areas in winter(Dec-2013) and summer(May-2014), the water quality of fish ponds was measured and the toxic algae specific gene in the water contaminated by toxin-producing algae were detected by using the real-time PCR technology of molecular biology techniques. The correlation analysis between different influencing factors was made to explore the physical and chemical influence for algal blooms.The results indicate that in May, the temperature is higher, the concentration of chlorophyll a in summer(Average: 297.46μg/L; Maximum: 1043.33μg/L, Minimum: 13.58μg/L) was higher than winter(Average: 186.01μg/L; Maximum: 541.08μg/L, Minimum: 1.67μg/L). And in different seasons, the concentration of chlorophyll a in the different layer of water in the fish ponds was changing. for example, in winter, the concentration changed a little, and tend to be like a consistent; but in the summer, the concentration was decreasing with the increasing of the depth of water. In addition to the concentration of nutrients, the pH, turbidity and electrical conductivity also affect the concentration of chlorophyll a in the water, the concentration of chlorophyll a had a positive correlation with pH and turbidity, but a negative correlation with electrical conductivity. According to the Nitrogen/Phosphorus(N/P) ratio, the growth of algae in Chiang Mai, Thailand is mainly restricted by the concentration of phosphorus in water.In winter, the microcystin producing algae account for over 80% of total cyanobacterial in water, but some fish ponds had a higher mcyB gene copy number in water. In summer, generally, the concentration of cyanobacterial is not growing significantly, but in some fish ponds, the cyanobacterial witch cannot produce microcystin takes advantage in water.