Study On The Occurrence Process Of Greenish Tide And The Contribution Of Micropropagation

In this paper,the use of ship and MODIS-TERRA satellite remote sensing monitoring methods to monitor the entire process of green tide from 2015 to 2017,and systematically investigated the distribution of green algae micropropagation in the South Yellow Sea.Ship monitoring results showed that in April 2015,sporadic floating algal blooms first appeared in the Rudong area of the South Yellow Sea.Afterwards,the green tide gradually showed a massive distribution and large-scale band distribution,and gradually moved towards Dafeng and Sheyang.And the Yellow Sea and other coastal areas of the Yellow Sea drift.Satellite remote sensing monitoring results are similar to ship monitoring.On May 19,satellite remote sensing first monitored small-scale floating green tides in Yancheng coastal waters.The area and coverage of green tides rapidly increased and drifted northwards to Shandong Peninsula.It landed on Qingdao on July5th,covering peak areas of 594 km² and 52700 km² respectively;by mid-July,the green tide gradually disappeared.The distribution characteristics of the microscopic propagules in the South Yellow Sea are consistent with the green tide drift trajectories.From March to May,the core dense areas of the micropropagated body are mainly distributed in the radiation sandbars in the offshore waters of the southern Yellow Sea in Jiangsu,with a peak distribution of up to 960 ind·L^-1;With the drift of the green tide to the north,the core dense area of micropropagation also gradually moved northwards in July,peaking in the coastal waters(476 ind·L^-1).In April 2016,the sporadic buoyant algae first appeared in the Rudong area of the South Yellow Sea,after which,the green tide gradually showed a massive distribution and large-scale strip distribution,and gradually moved to the Yellow Sea in Dafeng,Sheyang and Binhai.The drift in the central sea area.Satellite remote sensing monitoring results are similar to those of ship monitoring.On May 25,satellite remote sensing first monitored small-scale floating green tides in the coastal waters of Yancheng.The area and coverage of green tides rapidly increased and drifted northward to the Shandong Peninsula.Nearshore,landing in Qingdao on June 27th,the peak areas of coverage and distribution were 536 km² and 57,212 km² respectively;by mid-July,the green tide gradually disappeared.The distribution characteristics of microscopic propagules in the South Yellow Sea coincided with the drift trajectory of green tides.In March,the core dense areas of micropropagated propagules were mainly distributed in the radiation sandbars in the coastal waters of the southern Yellow Sea,with a peak value of 230 ind·L^-1.With the drift of the green tide to the north,the core dense area of micropropagation in May also gradually moved northward to the Dafeng and Sheyang sea areas,peaking in the Dafeng area(480 ind·L^-1);The overall proliferation of micropropagated organisms is reduced,and the dense core area is distributed between Dafeng(32 ind·L^-1)and the coastal waters(12 ind·L^-1).In April 2017,sporadic buoyant green tide algae first appeared in the Rudong area of the South Yellow Sea.Afterwards,the green tide gradually drifted to the middle reaches of the Yellow Sea,such as Dafeng,Sheyang,and Binhai.The massive distribution pattern was only observed in May.In June,there were sporadic floating green tide algae in Sheyang and the coastal waters.No floating algae was found in other sea areas.Satellite remote sensing monitoring results are similar to those of ship monitoring.On May 22,satellite remote sensing first monitored small-scale floating green tides in Yancheng coastal waters.The area and coverage of green tides rapidly increased,and drifted northwards to Shandong Peninsula.Nearshore,landing in Qingdao on June 15th,the peak coverage and distribution area was only 302 km² and24627km²;after June 15th,the green tide area gradually decreased and began to die.The distribution characteristics of the microscopic propagules in the South Yellow Sea are consistent with the green tide drift trajectory.From March to May,the core dense areas of the micropropagated body are mainly distributed in the radiation sandbar area of the offshore waters of the South Yellow Sea in Jiangsu,with a peak distribution of230 ind·L^-1;With the drift of the green tide to the north,the core dense area of micropropagation also gradually moved northwards in July,peaking in the coastal waters(28 ind·L^-1).The differences in the micropropagation of green tide algae in the truss area of Jiangsu Province in the South Yellow Sea showed that the micropropagation density of green tide algae in the truss area was significantly lower than that in 2016,and the core density area of the green tide algae micropropagation was increased.The distribution is the same;from January to March,the core dense area of micropropagation is mainly distributed in Rudong Zhongsha,and in the early stage of the green tide?from April to May?,the core area of micropropagation is mainly distributed in the Dafeng radiation sandbar area.ITS and 5S rDNA molecular detection showed that the sequences of the floating green tide algae from different sections were identical,and the sequences of the floating green tide algae and the green tide algae micropropagated samples were consistent.In order to further explore the microscopic propagules of green tide algae in the South Yellow Sea and reduce the original biomass of green tide,this study tested various materials used for the attachment and germination of three kinds of green algal spores.The culture experiment showed that:1)The materials used in the porphyra twigs?bamboo and jute twine?showed a higher adhesion rate;2)The jute rope was the best substrate for the attachment and germination of three green algal spores;The amount of spores attached to the hemp rope was the highest,and the amount of spores attached to bamboo was the highest.At the same time,it was found that when the temperature of light culture was 20°C and the light intensity was 120?mol·?m²·s?^-1,the micropropagation of green tide algae was most suitable for germination.This study clearly describes the annual occurrence of the green tide in the Yellow Sea,and provides the basis for further revealing the mechanism and periodicity of the rapid outbreak of the green tide in the Yellow Sea.It also explores the relationship between the green tide microscopic propagule and the outbreak of the Green Tide in the South Yellow Sea.