Study On Seasonal And Spatial Changes Of Barnacles Attached On Mangrove Seedlings And Preliminary Research On Terrestrial Plant Antifouling Method

The investigation on the distributions of barnacles attaching to the stems of mangrove seedlingsKandelia candel (L.) Druce and Avicennia marina (F.) Vierh during two years was carried out in Zengying, Xiamen.The results show: 1. There were 3 species of barnacles in the artificial mangroves of Xiamen. They were Balanus amphitrite amphitrite Darwin, Balanus albicostatus Pilsbry and Euraphia withersi Pilsbry. 2. The absolute height of habitat where the barnacles located was one of the main ecological factors which were the restrictions of their distributions. The total numbers of large barnacles (Balanus amphitrite amphitrite and Balanus albicostatus ) and the absolute height which they located were the negative correlation. The absolute height contained two aspects, one was the elevations where grew the mangroves,the other was the tree heights which the barnacles attached on. The higher land elevation was, the higher tree height was, the fewer the total numbers of large barnacle were. However, the impacts of absolute elevation on different types of barnacle were different. Large barnacles located at the lower elevation, and small barnacles (Euraphia withersi) lived in the higher position. Different barnacles' dominant species existed in different kinds of elevations. But the numbers of large barnacles attaching on Avicennia marina and the land elevations had much better correlativities. 3. Seasonal changes was another factor affecting barnacle attachment. Large barnacles in Kandelia candel and each kinds of barnacles in Avicennia marina, the quantities in each season were: Low land > Middle land > High land. But the quantities of small barnacles in Kandelia candel were highest only in spring, summer of 2006 .And in other seasons (fall and winter) they were consistent with the other barnacles' distributing tendency. Even if in the same type land, along with the seasonal variation, its dominant species also changed. In low land, the quantities of large barnacles in Kandelia candel were bigger than small barnacles only in summer. And small barnacles were the dominant species for a long time in the middle and high land. But in Avicennia marina, barnacles' interspecific competitions were fierce, so the changes of the dominant species were big. The seasonal dynamic differences of barnacle attachments were influenced by their own growth and reproduction cycle .The attachment peak of Balanus amphitrite amphitrite was winter and spring (from November to April) , but Euraphia withersi was autumn (from August to October) .In spring and summer, the wave erosion caused by the typhoons caused Kandelia candel to peel their skins frequency. The barnacles which adhered to the skins fall off. So it caused that only the quantities of Euraphia withersi in the middle and high land in Kandelia candel increased in the first year. The average numbers were 14.7 and 19.7 in several. Other types' barnacles experienced attachment, growing up, falling off, so the influences to Kandelia candel were not big finally. But, in Avicennia marina, the quantities of each kind of barnacles had increased obviously. 4. The mangrove species where the barnacle attached was the third impact factor. Euraphia withersi can adapt to different mangrove attachment better than other barnacles. The mangrove species which can peel barks obviously (Kandelia candel) can avoid the harm of the barnacles. The artificial mangroves, to prevent sufferring from the barnacles, the planting area should choose the higher elevation or artificial boosted the elevation of the beach. Choosing Kandelia candel as the main tree species can reduce the harm of the barnacles.In the extract of terrestrial plant materials, it was found that the toxicities of every plant extracts had some relationships with the type of the extractions they used. The effects which used ethyl acetate to extract were best. Toxic effects of the substances had a great association with the solubility which they adopted. The effects of different plant families had some certain differences. Even if the plants were the same family, there were also some differences when they belonged to different genus. The insecticidal activities which plants belonged to the same family and genus were closer. Generally speaking, the effects of Liliaceae and tannin were better than others. For example,The LC₅₀ of Allium cepa ethyl acetate extract was just 8×10^-6 g/cm³. In practical use, in order to obtain better results, it was appropriate to choose the extracting solvents in according with the plant organisms. With the prolonging of exposed time, LC₅₀ of the extracts were getting lower and lower, but changing ranges were different. Using ethyl acetate, change scopes of the extracts' LC₅₀ in 12 h were bigger.