Characteristics Of Community Structures Of Phytoplankton And Protozoa In The Salt Lakes, Tibet

Saline lake is a kind of extreme lakes type. China is a country withmany salt lakes, in which there are rich mineral and biological resources.Before the1970s geological scholars mainly focused on the study ofgeological minerals in Saline Lake. Then with the development of scienceand technology, people put more attentions to the reseaech of salt lake biota.The phytoplankton and protozoa of24salt lakes in Qiangbei region, Tibethad been investigated in spring,2009. We also investigated thephytoplankton of6salt lakes in Naqu region, Tibet and8salt lakes in Tibethad been in summer and autumn,2012. Through statistical analysis of alarge number of original data to analyze the community composition,density and biomass, as well as species diversity indices and othercharacteristics of community structures of phytoplankton and protozoa, inorder to enrich the plankton resources and ecological information of saltlakes in Tibet, and also provide the certain reference for the developmentand utilization of salt lake resources.The main results as below:1. The phytoplankton of24salt lakes in Qiangbei region, Tibet had been investigated in spring(4.29-5.19),2009. A total of96species ofphytoplankton were identified, belonging to50genera of6phyla.Bacillariophyta (24genera56species) were dominant in species richnessby58.33percentage, followed by Cyanophyta (9genera18species,18.75%) and Chlorophyta (13genera17species,17.71%). The others wereEuglenophyta (2genera3species), Cryptophyta (1genera1species) andPyrrophyta (1genera1species). A total of38species of protozoa wereidentified. Sarcodina (22species) were dominant in species richness by57.89percentage, followed by Ciliata (10species) and Mastigophora (6species).The phytoplankton of6salt lakes in Naqu region, Tibet had beeninvestigated in summer (7.31-8.9),2011. A total of38species ofphytoplankton were identified, belonging to24genera of5phyla.Bacillariophyta (12genera23species) were dominant in species richnessby60.53percentage, followed by Euglenophyta (4genera6species species,15.79%). The others were Cyanophyta (4genera4species), Chlorophyta(3genera4species), Xanthophyta(1genera1species).The phytoplankton of8salt lakes in Tibet had been investigated insummer and autumn (7.4,7.5,10.13),2012. A total of100species ofphytoplankton were identified, belonging to43genera of4phyla.Bacillariophyta (21genera68species) were dominant in species richness by68.00percentage, followed by Chlorophyta (12genera16species),Cyanophyta (9genera15species) and Pyrrophyta (1genera1species).2. Most of phytoplankton in Tibet salt lakes are euryhaline species oreuhalobic species coming form fresh waters, which can adapt to a widerange of salinity. Only a few, like Spirulina major, Rhizosolenia sp.，Cocconeis placentula and Amphora ovolis are typical saline species.Bacillariophyta were dominant obviously. According to the proportion ofbiomass and density of each phyla to do attribute classification, the resultsshow that57.89%of the salt lakes belong to diatoms lake, and in the othertype of lakes diatom also occupied the position of the secondary dominantspecies. The main dominant species were Navicula sp. and Nitschia sp.Most of the protozoa in24salt lkes in Qiangbei region,Tibet whichwere investigated in spring (4.29-5.19),2009were Sarcodina. Sarcodinaaccounted for the largest proportion in20salt likes, especially Niudu Lake,Amucuo, Caiduochaka and Pengyancuo, in which there were onlySarcodina.The main dominant species of protozoa were Sarcodina,especially Arcella sp., Centropyxis sp. and Difflugia sp.3. The average density and biomass of phytoplankton in24salt lakesof Qiangbei, Tibet in spring(4.29-5.19),2009were163.55×104cells/L and1.6845mg/L, respectively. The average density and biomass of protozoawere11145.83ind./L and0.3709mg/L, respectively. The average density and biomass of phytoplankton in6salt lakes ofNaqu,Tibet in summer (7.31-8.9),2011were168.64×104cells/L and1.5752mg/L, respectively.The average density and biomass of phytoplankton in8salt lakes ofTibet in summer and autumn(7.4,7.5,10.13),2012were191.66×104cells/Land1.3201mg/L, respectively.4. The value of H′, D, J of phytoplankton in24salt lakes of Qiangbei,Tibet in spring(4.29-5.19),2009were during0.44to2.50,0.14to1.87and0.21to1, respectively. The value of H′, D, J of protozoa in24salt lakes ofQiangbei, Tibet in spring(4.29-5.19),2009were during0to1.79,0to0.67and0to1.The value of H′, D, J of phytoplankton in6salt lakes of Naqu,Tibet insummer (7.31-8.9),2011were during0.09to2.17,0.13to1.74and0.45to0.84, respectively.The value of H′, D, J of phytoplankton in8salt lakes of Tibet insummer and autumn(7.4,7.5,10.13),2012were1.58to2.69,1.04to3.21and0.52to0.9, respectively.Although this paper investigated the characteristics of communitystructures of phytoplankton in the salt lakes in Tibet, but the annual surveysites were neither the same, nor do monitoring year by year. The in-depthstudy on seasonal succession of or ganisms, annual population dynamics of plankton, and the relationship with environmental factors are very few. it isnecessary to establish a long-term observation station or research base inthe typical saline lakes of different places.The in-depth research on ecologyof saline lakes is very important and significant for the change on theglobal environment exploitation and utilizatio of natural resources in salinelakes.