Mar. Environ. Res. (2009)

　　doi:10.1016/j.marenvres.2009.10.007

　　Shao Jun Pang¹*, Feng Liu^{1, 2}, Ti Feng Shan¹, Na Xu^{1, 2}, Zhi Huai Zhang¹, Su Qin Gao¹ , Thierry Chopin³, Song Sun¹

　　¹ Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P.R.China.

　　² Graduate University of Chinese Academy of Sciences, Beijing 100049, P.R.China.

　　³ University of New Brunswick, P.O. Box 5050, Saint John, NB E2L 4L5, Canada.

　　Abstract In 2008, Qingdao (36°06′ N, 120°25′ E, P. R. China) experienced the world largest drifting macroalgal bloom composed of the filamentous macroalga Ulva prolifera. No convincing biological evidence regarding the algal source is available so far. A series of field collections of both Ulva sp. and waters in various sites along Jiangsu coasts were conducted in March to May of 2009. Density of microscopic Ulva germlings in the waters sampled from different sites ranged from 7 to 3140 individuals L^-1, indicating the wide-spreading and long-term existence of the algae in the investigated region. Morphological and the nuclear ribosomal internal transcribed spacer ITS nrDNA and the chloroplast-encoded rbcL gene comparisons of 26 algal samples revealed that the algae collected from land-based animal aquaculture ponds mostly resembled the dominating blooming alga in 2008. Mismatch of Porphyra farming period with the occurrence of the green tide bloom, as well as the negative identification results of the sampled green algae from the Porphyra rafts eliminated Porphyra rafts as the principal and original source of the dominating blooming alga.

　　Key words: Ulva prolifera; Porphyra; green tide; algal bloom; eutrophication; ITS nrDNA, rbcL

　　l　　  Corresponding author:

　　l　　  Tel/Fax: 0086-532-82898831;

　　l　　  E-mail: sjpang@ms.qdio.ac.cn; (Pang Shao Jun)

　　l　　  Lab URL: www.mbccc.ac.cn.