Ulva usually attached to aquaculture rafts, rocks, and floating objects. Previous studies have shown that the world's largest green tides in the Yellow Sea originated from the attached Ulva on rafts. However, a large biomass of Ulva thalli has recently been found attached to Littorina sp. (periwinkles) in the Subei intertidal zone, but it is rarely observed on Bullacta exarata, Portunus sp., and other intertidal benthic animals. The population density of Littorina sp. on the Zhugen sand ridge is approximately 39.2 specimens/m². A maximum of seven Ulva macroalgae were attached to one periwinkle, and an average of 1.24 Ulva macroalgae were attached to each periwinkle. To determine the contribution of epizoic Ulva on Littorina sp. to floating green tides, these macroalgae were identified with a molecular biology method using internal transcribed spacer (ITS) sequences. Results showed the Ulva attached to Littorina sp. comprised just one species, Ulva flexuosa. Epizoic Ulva attached to intertidal benthic animals in the Zhugen sand ridge does not appear to be the main source of the green tide (the only dominant species is Ulva prolifera) outbreaks in the Southern Yellow Sea.

石莼通常附着在水产养殖筏、岩石和漂浮物上。此前的研究表明，黄海世界上最大的绿色潮汐起源于木筏上附着的石莼。然而，最近发现大量石莼菌体附着在Littorina sp 上。（长春花）在苏北潮间带，但在Bullacta exarata、Portunus sp上很少观察到。和其他潮间带底栖动物。Littorina sp.的种群密度。在诸根沙脊上，大约有 39.2 个样本/m ²。最多七个石莼大型藻类附着在一个长春花上，平均每个长春花上附着1.24 个石莼巨藻。确定表生期石莼对Littorina sp.的贡献。对于漂浮的绿潮，这些大型藻类通过分子生物学方法使用内部转录间隔区 (ITS) 序列进行鉴定。结果显示石莼附着于Littorina sp。仅包括一种，Ulva flexuosa。附在诸根沙脊的潮间带底栖动物上的生代石莼似乎不是南黄海绿潮（唯一优势种是石莼属）爆发的主要来源。