Distributions Of Floating Green Algae And Micro-propagules In The Formatting And Developing Processes In The Yellow Sea In2012

From2007to2013, the Southern Yellow Sea had experienced the large scalegreen-tide consecutively in China. The green-tide had significantly impacts theoffshore economy and environment at the Coast of the Shandong Peninsula. With thestudy of the origin of green tide in the Yellow Sea, the coastal waters of the SouthernYellow Sea had been concerned--Subei Shoal and its adjacent waters. Thedominating blooming algal was Ulva prolifera (Muell.) J. Agardh (Chlorophyta,Ulvophyceae). It is necessary to make a research in the Jiangsu offshore, in which wasconfirmed as the nursery for macroalgal blooms. Based on the monthly surveys andlaboratory studies the Southern Yellow Sea and Subei Shoal and its adjacent watersduring March to June in2012, we analyzed the process of U. prolifera green tidedevelopment in the Southern Yellow Sea, species composition and biomass changesof the attached green algae in the Porphyra yezoensis aquaculture rafts, the temporaland spatial distribution of green algal micro-propagules and the influencing factors.The main results are as follows:1. Floating green algae first appeared in late April, which was only a small amountof floating algae in the Southern Yellow Sea, with the average biomass of macroalgaeat only0.45g/m2. However, biomass of floating green algae increased rapidly inmid-May, to4.60g/m2—10times greater than before. In addition, the distributionarea reached8700km2, and the weight of macroalgae reached40,200tons. Withmacroalgae increasing, by early June, the average biomass of floating green algae hadreached9.51g/m2, and the distribution area was at36,400km2. At the same time, theweight of floating green algae was346,000tons. This proved that the green algae should appear firstly in the southern area and gradually extend northward. Eventually,it was widely distributed in the Southern Yellow Sea.2. Although a few other macroalgae(e.g. U. linza, C. groenlandicus) were identified,one single specie (U. prolifera) was absolutely dominant (>98%) in the floating greenalgal patches at the early stage of green tide.The dominated specie was U. prolifera ina proportion of more than98%(cruiseⅠ). With the expansion and migration of greentides, U. prolifera maintained its absolute dominance, accounting for nearly98%.3. The micro-propagules of green algae were widely distributed in the water andsediment in Jiangsu nearshore from March2012to June, where was large number ofmicro-propagules unit water.The biomass of micro-propagules decreased graduallyfrom inshore to offshore area, which distribution trends diffused outward from the raftin the study area. Besides, higher values were mainly observed in the adjacentPorphyra farming area, which spread out outward from the center of raft in seaweedfarming area. The number of micro-propagules was close to zero far shore.4. The distribution of micro-propagule of U. prolifera was consistent with theprocess of green tide formation and development in Yellow Sea. It was first appearedin the Subei Shoal, which then continued to expand. Afterwards, it was expanded tothe middle of Yellow Sea.