Molecular identification of green algae from the rafts based infrastructure of Porphyra yezoensis

To provide more information on the origin of the Ulva prolifera bloom in Qingdao sea area in China from 2007 to 2011, the diversity of green algae growing on the rafts of Porphyra yezoensis on the coast in Jiangsu Province was investigated based on ITS, rbcL and 5S sequences. Eighty-four of green algal samples from various sites and cruises in 2010 and 2011 were collected. According to ITS and rbcL sequences, samples from the rafts of P. yezoensis fell into four clades: Ulva linza-procera-prolifera (LPP) complex, Ulva flexuosa, Blidingia sp. and Urospora spp. However, based on the 5S rDNA, a more resolved DNA marker, only one of the 84 samples belonged to U. prolifera. Combined with the previous reports, it is likely that U. prolifera bloom in Qingdao sea area might consist of more than one origin, and Porphyra cultivation rafts might be one of the causes.