Study On The Community Composition And Seasonal Dynamic Of Protozoa In Typical Coastal Habitats Of Yantai

As an important ecological unit in the marine ecosystem,protists play key roles in the processes of global primary productivity and the carbon consumption.Facilitated by the high-throughput sequencing techniques,the importance of protists to aquatic systems has been widely acknowledged in the last decade.However,less information is known about the protistan communities in coastal area,compared to the pelagic ocean.In this work,we carried an investigation on the protistan biotic interactions and seasonal dynamics in three typical coastal habitats along Yantai city,northern Yellow Sea of China.?i?Protistan community composition and the biotic interactions in the estuarine and littoral zone of Yantai.Surface water samples were collected during a term from March 2018 to February 2019 on the estuarine and littoral zone of the northern Yellow Sea,for which the protist diversity was assessed by sequencing of the V4 18S rDNA region.Data analysis shown that there was no statistically regional difference between two sampling sites,and Alveolata,Chlorophyta,and Stramenopiles were the most dominant phytoplanktonic protists in the investigated coastal area.The community composition displayed strong seasonal variation.The abundant families Dino-Group-I-Clade-1,and Ulotrichales_X had higher proportions in spring and summer,while Bathycoccaceae exhibited higher ratios in autumn and winter.Alpha diversities?shannon and simpson?were highest in autumn and lowest in spring?ANOVA,P<0.05?.Nutrients(SiO₄^2-,PO₄^3-),TOC,and pH seemed to drive the variation of alpha diversity,and temperature,PO₄^3-and TON were the most significant factors influencing the whole protist community.Co-variance network analyses revealed frequent co-occurrence events among ciliates,chlorophytes and dinoflagellate,suggesting biotic interactions induced by predation,parasitism and mixotrophy.This study also provides basic data for future studies on the ecological processes of planktonic protozoa in similar water environments.?ii?Diversity,community composition and seasonal distribution of ciliates in estuarine and intertidal zone of Yantai.In this study,community composition and seasonal distribution of planktonic ciliates in estuarine and intertidal zones were studied by mining 18S rDNA high-throughput sequencing data of protozoa in estuarine and intertidal zones.The results shown that Spirotrichea,CONThreeP and Oligohymenophorea were revealed as the most dominated planktonic ciliates in the studied estuary and intertidal zone.The community composition of ciliate displayed strong seasonal variation in genus level:The relative abundance of Tintinnopsis₀9 was highest in winter,and Stenosemella has highest abundance in Spring.Alpha diversity?Chao 1?was highest in winter and lowest in Spring.RDA analysis shown that temperature,ammonium and nitratewere were the main environmental factors which driven the seasonal change of ciliate's community structure.The genus Bistichella and Strombidiida_EXX were significantly correlated with ammonium and nitrate concentrations.?iii?.Diversity,community composition and seasonal distribution of ciliates in aquaculture farming pond.Classes Spirotrichea,CONThreeP and Colpodea were revealed as the top dominant groups in the planktonic ciliates of the studied aquaculture habitat,and the dominant genera were Askenasia,Colpoda and Favella.The variation of ciliate community showed significant differences among four seasons.Strombilidiidae_FX had higher proportions in summer while Colpoda exhibited ratios in winter.The alpha diversity estimators of ciliates were highest in June and lowest in March.RDA analysis shown that Temperature,pH,ammonium and phosphate were the main factors driving the seasonal change of ciliates community structure.Colpoda was significantly negatively correlated with temperature and Favella has significantly positive correlation with ammonium.This study provides basic data for understanding the seasonal distribution of ciliates in the aquaculture pond and hopes to provide some basic dates for the establishment of ecological regulation in the aquaculture environment of sea cucumber.