- Theorerical results: To produce the accurate, synchronous, and continuous data of the environmental factors at the fixed stations. These data can serve in the purposes as study, teaching, and warning to the environment. - Applied results: the collected data were the parameters in annual national environmental state report - The analytical results in 2021 showed: In water Environmental quality at most stations were at the "low environmental pollution" (RQ <1) in all surveys. However, Dinh An station in December had RQ = 1.13, at the "average environmental pollution". The factors that make RQ index increase at the stations were coliform, Fe, nitrate, and TSS. Nha Trang, Phan Thiet had the stable and best environmental quality with RQ from 0.11 to 0.14 in surveys. Ganh Rai and Ha Tien stations also had good environmental quality with the RQ values from 0.25 to 0.38, from 0.53 to 0.75 at Song Doc, from 0.28 – 0.53 at Rach Gia and from 0.5 – 1.14 at Dinh An. Phu Quy offshore station has good environment with RQ = 0.31, at the “low environmental pollution” in April In sediment Phan Thiet and Song Doc stations were at the level of lowest potential of adverse biological effect (SQG-Q < 0,1). The remaining stations were at medium potential of adverse biological effect (0.1 < SQG-Q < 1). For the Phytoplankton: A total of 362 phytoplankton species/subspecies were recorded, of which diatoms accounted for 59.39%. Other Cyanobacteria , Euglenophyta, Charophyta, Ochrophyta, Haptophyta, và Cerozoa accounted for <3% of the recorded species. 32 species of potentially harmful phytoplankton belonging to 5 phyla were recorded, of which the dinoflagellates had the most species (20 taxa), and the least was Haptophyta (1 taxa). The harmful phytoplankton frequently appear at the stations are Akashiwo sanguinea, Trichodesmium thiebautii, Pseudo-nitzschia spp. in April. Pseudanabaena sp., Oscillatoria sp., Pseudo-nitzschia spp. in October. Pseudo-nitzschia, Pseudanabaena sp., Trichodesmium erythraeum, and Oscillatoria sp. in December. However, the highest cell density in all 3 sampling times. have not reached the warning threshold of closing the farming area to control (Todd, 2003). For the Zooplankton: A total of 207 zooplankton species were recorded, of which group Copepoda accounted 151 species. The highest average density of zooplankton was recorded at Rach Gia station (226.297 individuals/m3 in October, 25.980 individuals/m3 in April, and 75.185 individuals/m3 in December). The Phu Quy offshore station had the lowest density at the 10-5m layer (762 individuals/m3). For the Benthos: A total of 114 benthos species were recorded, of which class Polychaeta accounted for the highest proportion, and Echinodermata accounted for the lowest. Phan Thiet station has the highest average density, reaching 2.942 individuals/m2, however the largest biomass was in Rạch Giá station, reaching 63,75g/m2 in April. Song Doc station had no individual in October. In the period 2017 - 2021, there was no clear trend for variation of chemical and ecological factors, phytoplankton, zooplankton, and benthos at the stations, except for the total mineral oil and grease tending to decrease. |