Allelopathic effects of Enteromorpha intestinalis (Ulvaceae, Chlorophyta) on Prorocentrum micans (Prorocentraceae, Dinophyta) Sun X., Xia Y. M., Xu N. J.* Key Laboratory of Applied Marine Biotechnology, Ministry of Education, Marine Biotechnology Key Laboratory of Zhejiang Province, School of Marine Sciences, Ningbo University, Zhejiang Ningbo315211, China *Correspondence author: E-Mail: xunianjun@nbu.edu.cn
Online published on 7 November, 2012. Abstract The allelopathic effects of seaweed Enteromorpha intestinalis were studied on the red tide microalgae Prorocentrum micans and the possible mechanisms were investigated by analysis of activities of antioxidant enzymes, alteration of membrane permeability and ultrastructure of P. micans cells. The P. micans was significantly inhibited by high concentrations of fresh tissues of E. intestinalis or their water phase extracts. The IC50 of fresh tissue of E. intestinalis on P. micans for six days was 6.23 mg.mL−1 and the water phase extracts was 0.018 mg·mL−1. The activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) significantly increased at 4 h, and decreased gradually till 24 h and finally reached the lower level of control group at 36 h. The level of malondialdehyde was significantly elevated indicating lipid peroxidation and oxidation stress by extracts of E. intestinalis treatment. The extracts of E. intestinalis altered the membrane permeability, as the intracellular concentration of Na+, K+, Mg2+ and Ca2+ decreased significantly after 36h. The cellular organelles including chloroplasts and Golgi complex were damaged. It was concluded that the E. intestinalis showed allelopathic effects on the P. micans inducing the physiological and morphological changes and finally caused the death of P. micans. Top Keywords Allelopathy, antioxidant, Enteromorpha intestinalis, membrane permeability, Prorocentrum micans, red tide, sea weed. Top |