Effects of temperature, salinity and irradiance on the growth of the harmful dinoflagellate Prorocentrum donghaiense Lu

The effects of temperature, salinity and irradiance on the growth of the causative organism of large-scale red tide along the east Chinese coast Prorocentrum donghaiense were examined in the laboratory. The optimum irradiance for growth was >30 μmol m−2 s−1. A moderate specific growth rate of 0.33 d−1 was observed at 2 μmol m−2 s−1, the minimum irradiance in the experiments, and photoinhibition did not occur even at 230 μmol m−2 s−1, the maximum irradiance in the experiments. From 42 different combinations of temperature (10–31 °C) and salinity (10–40 psu) under saturated irradiance, P. donghaiense exhibited its maximum specific growth rate of 0.77 d−1 at a combination of 27 °C and salinity of 30 psu. Optimum growth rates of >0.60 d−1 were observed at temperatures ranging from 20 to 27 °C and at salinities from 25 to 35 psu. The organism was able to grow at temperatures ranging from 10 to 27 °C and at salinities from 20 to 40 psu, but it could not grow at temperature ≥31 °C or at salinities ≤10 psu. Temperature had the greatest influence on the growth rate, followed by salinity and the interaction between temperature and salinity. It is noteworthy that P. donghaiense adapts to low irradiance, low temperature ranging from 10 to 20 °C and a broad range of salinities, demonstrating its ability to dominate in estuaries, and bloom in early spring.