ความสัมพันธ์ระหว่างแบคทีเรียกับชุมชนแพลงก์ตอนพืชที่เกี่ยวข้องกับการเกิดปรากฎการณ์น้ำเปลี่ยนสีบริเวณชายฝั่งทะเลบางพระ ชลบุรี / ปิยะรัตน์ เซ้าซี้ = Relationship between bacteria and phytoplankton communities associated with red tide in coastal area of Bangpra, Chon buri / Piyarath Saosee
The relationship between bacteria and phytoplankton communities associated with red tide at Bangpra coastal area, Chonburi province was studied every month from February 2003 to June 2004 and at weekly period during the rainy season between July to October 2003, which is the period of red tide phenomenon in this area. Density of phytoplankton and bacteria was determined from water samples. Chlorophyll biomass of phytoplankton was also determined in laboratory while physico-chemical parameters were measured in situ. Besides, secondary data on inorganic nutrients from the same time were also available for the discussion. Five groups of total of 52 genera of microplankton were recorded. Oscillatoria erythraeum and Chaetoceros spp. were frequently found in this area. Red tide occurred 12 times during this study, 7 times in rainy of 2003 and 5 times in rainy of 2004. Green tide of Noctiluca scintillans was recorded for 6 times and yellow-green-colored water from Noctiluca scintillans and Chaetoceros spp. occurred only one time. Diatoms and Ceratium Jurca caused red tide phenomenon for 5 times during the study period. Density of phytoplankton ranged from 1.20 x10⁴ to 5.51 X 10⁵cell per liter but during phytoplankton blooms, the density ranged from 6.19xl04 to 5.51 xl05cell per liter. Density of bacterial varied from 2.09 x10⁵ to 1.24 x 10⁶cell per milliliter. Relationship between bacteria density and phytoplankton density in sea water occurred in dry season because of bacteria uptake on dissolve organic matter released from phytoplankton. But in rainy, season dissolve organic matter also increases from run off, so relationship between bacteria and phytoplankton were not clear. Natural population of bacteria did not show an adversed effect on phytoplankton growth. This may due to the diversity of bacteria and variability of sources of nutrient for bacteria in seawater. Bacteria isolated from seawater and identified using DNA sequencing technique inhibited growths of C. curvisetus and S. costatum at the densities of Bacillus sp. ≥ 1.53 x10⁵ cell per milliliter, Pseudomonas sp. concentrations 2.89 x10⁴ cell per milliliter and unidentified bacteria concentrations ≥1.16 x10⁵ cell per milliliter. For N. scintillans, bacteria that affected growth of this dinoflagellate were Bacillus sp. at concentrations 1.10 X 10⁵, Pseudomonas at concentrations 8.60 X 10⁴ cell per milliliter and unidentified bacteria at concentrations 8.80 X 10⁴ cell per milliliter.