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Green tides are caused by the proliferation of chlorophytes under suitable hydrographic conditions. These blooms lead to environmental degradation and negatively impact the waters and seagrass beds, as well as fishing and other recreational activities in the bay. A comprehensive ecological understanding of the bloom dynamics, including the origin and persistence, is needed to foster management decisions. The algae in the great majority of green tide blooms usually belong to two genera of Ulvophyceae, Ulva and Enteromorpha. Ulva has been observed more often in recent years. In China, green tides occurred for the first time in the middle area of the Yellow Sea in 2007, and a large-scale algae blooming broke out in the middle and southern areas of the Yellow Sea in late May 2008. We identified them as Ulva prolifera by comparative analysis of the rDNA internal transcribed spacer 1 (ITS1), 5.8S and ITS2 sequences in combination with microscopic observation. Morphological differences were found between the free-floating algae and the attached thalli. Various reproduction patterns of the free-floating algae include sexual, asexual and vegetative propagations, which played important roles in the long-term green tide persistence in China. The ITS sequences of the blooming algae were identical to those of the samples from the Lianyungang sea area but were different from the attached samples from the Qingdao sea area. The results infer that the blooms are originated from other sea areas rather than from the local attached populations.

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Low-frequencypIioiion spectra in a-SiN, : H/Si lieteros tructures have hcen observed by iiicaiis o f Driflouin light srattcring. Mcasurcinent of the frcqiicncy shift on longitudiiid and transversc acoustic ~JIOIIOIIS as well as on surface phonons enabled us to extract acciiratcly two independcnt &$tic moduli: cI1 and c44 dcduced from phase veJocities of bulk acoustic inodcs and scattc:ring wavevcctor, within effective medium approxima tion.

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