Community Structure Of Picoeukaryotes In Polar Region Sea And Relationship With Environment Factors

Picoeukaryotes play an important role in material circulation and energy flow in the marine ecosystem,and itself has rich diversity,and as the main contributor for primary productivity in the marine.Global warming leads to Arctic and Antanrtic temperature rise quickly in recent years,and in such a changing Arctic and Antanrtic environment,the community and diversity of picoeukaryotes should change dramatically.In addition,because of the special geographical location of the Arctic and the Antanrtic,the study of polar picoeukaryotes is relatively rare compared to the rest marine of the world.In order to understand the diversity,characteristics,communities of picoeukaryotes and the relationship between picoeukaryotes and environment in the polar waters,the paper by using molecular biological technology such as 454 sequencing technology,study the diversity,community structure,spatial distribution and the relation to environmental factors of picoeukaryotes in the Chukchi Sea and the northern tip of Antarctica Peninsula waters in Summer 2012.The main results as follows:(1)Six supergroups of picoeukaryotes were obtained in the northern tip of the Antarctic Peninsula: Stramenopiles,Alveolata,Haptophyta,Chlorophyta,Amoebozoa and Rhizaria were dominant groups but the distribution of the communities in different samples is significantly different.The dominant groups(average relative abundance>1%)are further divided into the following 14 classes: Bicosoecida,Bacillariophyceae,Mediophyceae,Dictyochophyceae,Pelagophyceae,Spirotrichea,Dinoflagellata,Ciliophora,Mamiellophyceae,Prasinophytae,Haptophyceae,Cercozoa,Discosea,Cryptophyceae.There is a huge difference in the distribution of each class in the community,in which the Dinoflagellates and Haptophyceae are dominant classes in this area,with an average relative abundance of 13.45% and 13.87%,respectively.Nutrients,especially ammonium,phosphate and salinity play an important role in the diversity and communities of picoeukaryotes in the northern tip of the Antarctic Peninsula.(2)The study of picoeukaryotes in the Chukchi Sea area found that there are 6 classes of picoeukaryotes with a relative abundance of more than 1%.They are Chrysophyceae,Mediophyceae,Mamiellophyceae,Spirotrichea,Dinophyceae and Tremellomycetes,of which autotrophic picoeukaryotes accounts for about 85.2%%,has an absolute advantage.Nitrate plays an important role in the community structure of picophytoplankton in the Chukchi Sea.Heterotrophic Spirotrichea feed on autotrophic pico-phytoplankton,and their community distribution is affected by the classes of Chrysophyceae,Mediophyceae and Mamiellophyceae.(3)There are some differences and similarities in the distribution of the communities of picoeukaryotes in the northern tip of the Antarctic Peninsula and Chukchi Sea:The Stramenopiles are dominant species in both sea areas and have relatively high abundances.The average relative abundance of the waters in the northern tip of the Antarctic Peninsula is 40.02%,and that of the Arctic Chukchi Sea is 38.90%.However,the distribution of classes belong to Stramenopiles is very different: Bicosoecida(average relative abundance of 2.9%),Bacillariophyceae(9.21%),Dictyochophyceae(8.98%),Pelagophyceae(4.46%),Chrysophyceae(0.23%),Mediophyceae(2.02)were found in the northern tip of the Antarctic Peninsula,of which the relative abundances are all less than 10%;in Chukchi sea,the main species are Chrysophyceae(36.40%)and Mediophyceae(2.42%),and the relative abundances of Bicosoecida,Bacillariophyceae,Dictyochophyceae,Pelagophyceae are all less than 0.02%.As the second most dominant group in the Chukchi Sea,the distruction of Chlorophyta in the northern tip of the Antarctic Peninsula was low(average relative abundance is 5.45%);the Haptophyta was dominant in the northern tip of the Antarctic Peninsula and widely distributed.However,in the Chukchi Sea,the Haptophyta accounted for only 0.01%;Rhizaria was found in both sea areas,but its relative abundance was not significant.The relative abundance of Rhizaria was 1.37% in the northern tip of the Antarctic Peninsula,and 0.98% in the Arctic Chukchi Sea.The relative abundance of the Alveolata in the Chukchi Sea is 8.98%,which is far less than that in the northern tip of the Antarctic Peninsula(25.99%).Fungi are widely distributed in the Chukchi Sea and are the fourth most dominant group in this area,but in the northern tip of the Antarctic Peninsula,we don not found the presence of fungi.;the community of Amoebozoa occupies only0.05%in the Chukchi Sea but has a relative abundance of more than 1%in the northern tip of the Antarctic Peninsula.(4)The diversity of picoeukaryotes in the northern tip of the Antarctic Peninsula(average Shannon index: 4.72,average Simpson index: 0.07)was higher than that of the Chukchi Sea(average Shannon Index: 3.09,average Simpson index: 0.19).