| Abstract: | A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions
and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic
phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and
DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during
the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species,
accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation,
and severe saline intrusion were likely responsible for the bloom of C. geminatum. |
