Temporal-Spatial Distribution Pattern And Water Quality Preliminary Evaluation Of Benthic Diatoms In The Lalin River

The rivers is the most complex ecosystem on the earth,which is the hotspots of pathway in material circulation,regulating climate and biodiversity.Benthic diatoms is indispensable link of the water ecological system in the energy exchanges and information circulation.Meanwhile,benthic diatoms can directly or indirectly as an indictor for monitor the water quality.Recently,benthic diatom is widely performed as an indicator for evaluated the ecological status in river ecosystem.However,there is few survey focus on the pattern of spatial and temporal distribution of benthic diatoms.Therefore,the study of benthic diatoms in Lalin river basin is necessary.In this study,benthic diatoms and environmental factors were collected in the Lalin River in 2017 and 2018 respectively.A total of 30 sampling sites and 168 samples were collected.In this study,we focus on analysis the benthic diatoms of dominant species,composition and distribution pattern.Meanwhile,based on the multicariated statistical analysis to explored the correlation between benthic diatoms and environmental factors.Diatom index of biotic integrity was performed to understand the function of benthic diatoms in monitoring water quality and evaluate the ecosystem health.At the same time,we studied the ecological characteristics of the benthic diatom community in Lalin River at winter.It provides basic data and biological basis for Lalin River System,even the Songhua River in aquatic ecology,water quality monitoring and water pollution control.The main results are as follows:?1?During the study period,a total of 6 species of 3 genera belonging to Centricae and 135 species of 37 genera belonging to Pennatae were indentified.The main dominant species of Lalin River were:16 species were Navicula Bory?11.43%?,16species were Gomphonema Ehrenberg?11.43%?,has 15 species were Nitzschia Hassall?10.71%?.Our result revealed that the dominant species were divided into 14 genera and40 species which were Melosira varians,Navicula viridula var.rostellata,Hantzschia amphioxys,Gyrosigma scalproides,Navicula radiosafallax,Nitzschia intermedia,Cocconeis placentula.?2?Shannon-Weaver diversity index?H'?was from 0.77 to 3.12;Simpson's diversity index?D?ranged from 0.27 to 0.94,and Pielou Enveness index?J?varied from0.29 to 1.49;the Lloyd-Ghelandi Enveness index?E?was showed from 0.03 to 0.45.Through the four diversity indices to evaluate the diversity of the Lalin River,the results showed that there are abundant benthic diatom species in Lalin River with a relatively stable community structure.?3?The water temperature?WT?varied between 4.46?and 22.17?;the dissolved oxygen?DO?were from 0.50 mg/L to 4.68 mg/L;the specific conductance?SpCond.?ranged from 47.70 mS/cm to 1337.33 mS/cm;the pH varied from 5.40 to9.72;the oxidation-reduction potential?ORP?varied between 221.33 mV and 658.67mV;the turbidity?Tur?appeared between 1.16 NTU and 66.2 NTU;the chlorophyll-a?CHL-a?was showed between 0.26?g/L and 66.94?g/L;the velocity?Vel?varied from0.00 m/s to 0.87 m/s;total nitrogen?TN?varied between 0.13 mg/L and 8.43 mg/L;total phosphorus?TP?were between 0.05 mg/L and 1.43 mg/L;chemical oxygen demand(COD_Mn)varied between is 2 mg/L and 65.33 mg/L.The CCA showed that SpCond.,Tur,CHL-a,Vel,DO,WT,and ORP are the key factors dynamic the benthic diatom community structure of Lalin River.?4?Bsed on environmental factors to evaluate Lalin river water quality,the results showed that DO,TN and TP were Class V;COD_Mnn was Class I and II;the trophic state index?TSI?was moderate eutrophication.The water quality,evaluated with benthic diatoms,which were?-medium pollution and?-medium pollution.According to the benthic diatom diversity index,water quality was evaluated:Shannon-Weaver diversity index?H'?showed light pollution,and Pielou evenness index?J?was light pollution,Lloyd-Ghelandi evenness index?E?was ploysaprobic.According to the diatom index of biotic integrity?D-IBI?,the water quality of Lalin River was better.In summary,the water quality of the Lalin River was evaluated by multiple factors as light-moderate eutrophication.?5?In the survey,55 species and 28 genera of benthic diatoms were identified in winter.There was a total of six dominant species:Hannaea arcus,Achnanthidium catenatum,Gomphonema parvulum,Encyonema silesiacum,Melosira varians and Navicula viridula.Compared with the other three seasons,there was a obivous less in richness and dominant species number in winter.COD_Mnn was the key factor that drived the distribution of dominant benthic diatoms in winter.