Inhibition And Mechanism Of Wood Meals From Chinese Fir On The Growth Of Alexandrium Tamarense

Objective: In recent years, there had been an apparent increase in the occurrence of harmful algal blooms (HABs) in China, which had a major impact on ecosystem, human health, tour and economics development. Therefore, it is a spotlight in HABs field how to control HABs effectively. It is deemed to be a promising method applying alUelopathy to control HABs, since it is economical, effective and friendly to environment. In this paper, effects of the wood meals from different plants on the growth of Alexandrium tamarense were assessed, and the mechanism was put forward. In addition, the ecological risk was evaluated. The main objective of this study was to explore the possibility that the wood meals was used as a potential candidate to control HABs, and provide more information on algaecide with efficiency, low toxicity or innocuity to control HABs.Methods: The inhibitory effects of the wood meals on A tamarense were assessed by counting microalga cells under a CKX41 inverted microscope. The level of polyphenols in different wood meals were determined by Prussian blue assay; The essential oil from wood was extracted by steam distillation. The components of the essential oil and extracts from wood meal of Chinese fir with water or acetone-water were analyzed by GC-MS. The effect of fir essential oil on the morphology of microalgae was observed under CKX41 inverted microscope. The possible risk of ecology of the wood meal and essential oil of Chinese fir was evaluated by the acute toxiticy tests of Brachydanio rerio and Artemia sinica.Results: The results showed that the inhibition of fir wood meals on A. tamarense was stranger than that of other wood meals assayed. 0.2 g/L of fir wood meals was to demonstrated to inhibit remarkbly A. tamarense in the cell density of 2.88x106, 6.08xl06, 14.13xl06cells/mL whereas 0.5 g/L meals was showed to kill the algae efficiently. Sinking action of fir wood meals on microalga did occurred. Beside wood meal, extracts from fir wood meal with acetone-water or water were showed to inhibitA. tamarense. However, inhibition on A. tamarense did not positively correlated with level of polyphenol in different wood meal. The inhibitory effects of fir essential oils on A. tamarense were stronger than that of essential oils from other meals, which inhibited the microalgae growth at concentration of 5.0xl0"4g/L. Fir essential oil inhibited the motility of all algae assayed, and induced an ecdysis of A. tamarense, a quick lysis of Chattonella marina in a relatively short time. These results suggested that fir essential oils but not phenol of wood meals play an important role in the algaecide and that fir essential oil have a negative impact on different algae in various degree.Conclusions: The wood meal of Chinese fir inhibited remarkably the growth of A. tamarense. The essential oil and sinking action of fir wood meals be responsible for the inhibitory effect. Chinese fir (Cunninghamia lanceolata) is fast-growing and high-yielding plant, and widely distributed in Southern China. What's more, the wood meals from fir are often abandoned as byproducts in most cases. Collection of abundant cheap wood meals represented an easy and economical means of potential HABs control.