Studies On Baciliariophyta In Part Of Zhalong National Nature Reserve

Zhalong National Nature Reserve is located in the downstream of Wu yuer River,west of Songnen Plain. In1992, it was designated as one of the international importantwetlands.The wetland is a temperate continental monsoon climate with an averagetemperature of2-4.2℃, the average annual rainfall is416millimetre. It is the bestpreserved, most original and widest mire ecosystem among the same latitude area in thenorthern China.Samples were collected from six marked sampling sites in Zhalong NationalNature Reserve. We also collected samples randomly at the wetland. Sample collectiontook place in May2011, July2011, October2011, May2012, July2012and September2012. In total120samples were collected. We did the observations, identifications anddescriptions after isolating the diatoms and afterwards analysed the communitystructures and environmental factors. Main research results are as follows.1. We did the taxonomic studies of the diatoms in accordance with Round etal.(1990).There are119taxonomic units in all belonging to2classes,6orders,10families,36genera,99species and20varieties.1order,1family and2genera arecentric diatoms, while5orders,9families and34genera are pinnate diatoms.Biraphidinales was most abundant with66taxa, followed by Aulonoraphidinals with26taxa. Nitzschia had the maximum number of species (10species and2varieties),followed by Gomphonema with6species,5varietas and then Cymbella and Naviculawith9species.2. The majority of diatoms appeared in various sampling stations werecosmopolitan, up to59taxa. There are4peculiar marsh land taxa: Eunotia bilunaris,Caloneis silicula, Synedra montana, Tabellaria flocculosa. Eunotia bilunaris becamethe dominant species in2012, the Tabellaria flocculosa is the dominant species duringthe two years, which is keen on the water between oligosaprobic zone and mesosaprobiczone; during the2years research, we found a certain amount of species which is foundof alkalinity or saltwater, such as Epithemia sorex, Gyrosigma acuminatum, Nitzschianana, Nitzschia tryblionella, Rhopalodia gibba. We could often find the hight epiphytictaxa, such as Diatoma tenunis, Epithemia adnata, Hippodonta capitata; and the great majority of biatoms belong to mesosaprobic zone indicators in region, such asGomphonema truncatum, Amphora veneta, Craticul ambigua, Cymbella caespitosa.3. We measure the physical and chemical factor of all the sampling site during thegathering, the water temperature changed from8.3-30.1℃with a big span, thetemperature is highest in Summer, the average temperature is18.23℃in Spring, therange of temperature is obvious in Autumn and the average temperature is15.6℃; Thewater of the gathering area is alkalescence, severally is alkaline, the variation range ofpH is6.89-9.57; The electric conductivity is high, the average value is347.75μs/cm;The variation range of TN and TP are0.762-1.574and0.02-0.092mg/l, the data ishigher in2012compared with2011; the variation range of BOD5is7.4-16.6, theaverage value of sampling pointⅡis highest with11.31mg/l; the variation range ofCODcr and CODmn is20.3-62and6.21-16.3mg/l, there is a small difference duringtwo years. We made the Canonical Correspondence Analysis(CCA) combined thediatom’s community structure and physical and chemical factor, the results show that,the community structure is influenced by the pH、 the conductivity、 the watertemperature、TN、TP and the BOD5, among all the factors, the water temperature playedthe most important role and the pH and conductivity run the second place.4. We made the diversity analysis on the diatom gathering from the sampling sitesby using the Margalef diversity index, Simpon index, Shannon-Weaver index and Pielouindex, also, we conduct a preliminary assessment on the water combine the compositionand the community structure of diatom. The Margalef diversity index is between2.0-11.1. The variation range Shannon-Weaver index is0.98-5.64. The variation rangeof Simpson index is0.37-0.97. The variation range of Pielou equally index is0.34-9.09,among the large arrange.The results of the diversity analysis shows the water nutritionwas belong oligotrofphic to mesotrophic basically in protection zone, and the trend iscontinuously deteriorates.In this study, we firstly reported the diatom community composition and itsindicators of environment in Zhalong National Nature Reserve, analysis the dependencybetween the diatom and water environment of Zhalong National Nature Reserve,provide initial information for the environmental monitoring and protection.