Abstract: Based on the monitoring data of the eco-environment in Shantou Harbor from March 2009 to March 2010,this paper studied the composition of phytoplankton community and its sensitivity to the environment in the Harbor. A total of 322 phytoplankton species were identified, including 234 diatom species, 141 fresh-water and brackish water species, and 64 red tide species.The average abundance, Shannon index, and evenness index of the community were 3127.6×10⁴ cells·m^-3, 2.53, and 0.57, respectively, and Skeletonema costatum and Oscillatoria sp. were the dominant species throughout the year, with the dominance index being 0.066 and 0.038, respectively. There was a significant positive correlation between phytoplankton community composition and water temperature (r=-0.699, P<0.01), and the phytoplankton growth was mainly limited by water transparence. The relevance degree of phytoplankton composition and environmental factors showed that upstream input was an important source of Shantou Port pollutants, and the multi-scale and Pearson correlation analyses indicated that water temperature, salinity, and pH were the main factors affecting the phytoplankton community composition.

Key words: Low molecular weight organic acid, Red soil, Inorganic phosphorus, Acidity