Seasonal variation of dominant free-floating and attached Ulva species in Rudong coastal area, China

• Published in: Harmful algae 2013-08, Vol.28, p.46-54
• Main Authors: Han, Wei, Chen, Li-Ping, Zhang, Jian-Heng, Tian, Xiao-Ling, Hua, Liang, He, Qing, Huo, Yuan-Zi, Yu, Ke-Feng, Shi, Ding-Ji, Ma, Jia-Hai, He, Pei-Min
• Format: Article
• Language: English
• Subjects: 5S rDNA spacer regions; Algae; algal blooms; Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; aquaculture; Attached population; Autoecology; Biological and medical sciences; coasts; Free-floating population; Fundamental and applied biological sciences. Psychology; General aspects; Green tides; internal transcribed spacers; ITS sequences; Molecular identification; phylogeny; Plant cytology, morphology, systematics, chorology and evolution; Plants and fungi; Porphyra; Porphyra aquaculture raft; ribosomal DNA; seasonal variation; sequence homology; Thallophyta; Ulva prolifera
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2013.05.018

•We found seasonal variation of attached Ulva on Porphyra aquaculture rafts and species succession of free-floating Ulva at the early stage of green tides.•U. compressa, U. linza and U. linza collected from Porphyra rafts in April 2011 had identical ITS sequences with free-floating Ulva samples at the early stage of green tides.•U. prolifera collected from Porphyra rafts in March, November, December 2011 had identical ITS and 5S rDNA spacer sequences with the dominant green tides algae U. prolifera. In this paper, species compositions and seasonal variations of attached Ulva species on Porphyra aquaculture rafts and free floating Ulva species at Rudong coastal area, Jiangsu Province of China were investigated during 2010–2011. Based on the sequences analysis of nuclear-encoded ITS (including 5.8S rDNA regions) and 5S rDNA spacer regions, dominant species of both attached and free-floating Ulva samples were identified as Ulva compressa, Ulva linza, Ulva prolifera and Ulva flexuosa. Phylogenetic tree based on sequences of ITS and 5S rDNA spacer regions for attached and free-floating Ulva species was constructed, respectively. Species compositions of the Ulva population attached on aquaculture rafts varied with seasons, and U. prolifera was only found on aquaculture rafts in March 2011 during the 2010–2011 Porphyra yezoensis cultivation season, which had the same sequences of ITS and 5S rDNA spacer regions as that of the dominant species bloomed in the Yellow Sea of China in 2008. Dominant species of the free-floating Ulva population at the early stage of the green tide were U. compressa, U. flexuosa, and U. linza. Free-floating U. prolifera appeared in the middle of May, 2011. ITS sequence similarity rates of U. compressa and U. flexuosa between the attached and free-floating species were 100%. And ITS and 5S rDNA spacer sequences of the attached and the free-floating U. prolifera population also showed no differences. Further study showed that there were two types of free-floating U. prolifera population (Type 5S-A and Type 5S-B) based on 5S rDNA spacer sequences. The present study would provide some useful information for clarifying the outbreak mechanism of green tides occurred in the Yellow Sea, China.