Compensatory growth of the bloom-forming dinoflagellate Prorocentrum donghaiense induced by nitrogen stress *

Although the phenomenon of compensatory growth has been documented in some animals and higher plants, little information is available on its manifestation in marine microalgae. We have conducted the first study on the compensatory growth of the red tide causative dinoflagellate Prorocentrum donghaiense after its recovery from different nitrogen concentrations. The results showed that NaNO3 concentrations of 0 and 7.5 mg l−1 significantly reduced the growth of P. donghaiense, as compared to 37.5 and 75 mg l−1. When the microalgal cells were returned to 75 mg l−1, they exhibited subsequent compensatory growth. The most significant compensatory growth was found in those cells previously experiencing 0 mg l−1, followed by 7.5 mg l−1, indicating that compensatory growth depended on the extent of nitrogen stress they had been subjected to. Our results suggest that compensatory growth can be induced in the marine microalga P. donghaiense after its recovery from nitrogen fluctuation, and that this should be taken into consideration in the prevalence of P. donghaiense blooms in coastal waters.