【作者】 王涛；

【导师】 柴毅；

【作者基本信息】 长江大学 ， 渔业发展， 2022， 硕士

【摘要】 长湖位于荆州、潜江、荆门三市交界处,兼备蓄洪、航运、灌溉等综合功能,为长江中游区域典型的富营养化湖泊,也是国家级鲌类种质资源保护区。据相关报道显示,长湖2016年全面拆围之前处于中度富营养-富营养状态,局部达到重度富营养化,拆围之后长湖N、P营养盐水平呈下降趋势,水环境污染状况逐渐有好转趋势。高等水生植物和藻类作为水生态系统中初级生产者,两者相互制约,能对水环境因子起着调节作用,同时还可作为水生态系统中的指示生物,可直接反应水环境的优劣。本研究于2020年10月(秋)、2021年1月(冬)、4月(春)、7月(夏)对长湖高等水生植物及着生硅藻以及TN、TP、DO、COD等14个水环境指标进行了监测。对高等水生植物及着生硅藻种类组成、优势种、生物量、多样性指数(Shannon-Wiener指数、Pielou均匀度指数和Margalef指数)等群落结构特征进行分析,对水环境因子进行综合营养指数(TLI)分析,并利用Pearson相关性分析和冗余分析(RDA)对长湖高等水生植物、着生硅藻及水环境因子进行相关性分析,结果显示:(1)水环境因子:长湖水质全年呈弱碱性,p H平均变化范围为8.09～8.34,其中冬季采样点C11最高,达9.12。全年水温平均变化范围为8.08～32.32℃,其中夏季变化范围是30.30～36.90℃,C13采样点最高(36.90℃)。溶解氧全年水平均较高,平均范围为11.79-13.60,其中夏季最低(11.79),冬季最高(13.60)。总氮平均范围为0.39～1.91,其中夏季最高(1.91),C12采样点最高(0.39),秋季最低(0.39)。总磷平均范围为0.03～0.23,其中夏季最高(0.23),最高值(0.39)出现在C11采样点,冬季最低(0.03)。根据地表水环境质量标准(GB3838-2002)来看,长湖整体上处于Ⅲ类水状态,部分采样点处于Ⅳ类水状态。(2)水质评估:长湖水环境因子综合营养指数(TLI)分析结果显示,秋季、冬季、春季、夏季变化范围分别为32.68～60.13、33.02～61.17、33.32～61.23、39.66～66.44,全年TLI平均范围为33.12～61.76,整体处于轻度富营养化-中度富营养化程度,部分采样点接近重度富营养化程度。从Shannon-Wiener指数(H)来看,秋季H值变化范围为1.88～2.64,冬季为1.23～2.24,春季为1.68～2.30,夏季为1.80～2.32,均处于β-中污染～α-中污染范围。从Pielou均匀度指数(J)来看,秋季J值变化范围为0.44～0.94,冬季为0.46～0.91,均为轻污染～α-中污染状态;春季为0.72～0.90,夏季为0.63～0.86,均为轻污染～β-中污染状态。从Margalef指数(D)来看,秋季D值变化范围为2.04～3.68,属轻污染～β-中污染水平;冬季为1.84～2.49,为β-中污染～α-中污染水平;春季为1.92～3.08,为轻污染～α-中污染水平;夏季为2.03～4.17,为轻污染～β-中污染水平。综合上述各项指数分析结果来看,长湖水质整体处于β-中污染～α-中污染等级。(3)高等水生植物与着生硅藻群落结构特征分析:本次调查共鉴定出高等水生植物20科19属24种,其中挺水植物8科7属8种,漂浮植物3科3属3种,浮叶植物4科4属6种,沉水植物3科3属7种。根据重要值共确定长湖高等水生植物7个植物群丛,分别为芦苇+莲+喜旱莲子草、凤眼莲、芦苇+喜旱莲子草、芦苇、菹草、菱、芦苇+水蓼+莲。芦苇、香蒲、菹草属于耐污种,多分布于重污染水域,菱、荇菜对高浓度N、P的水域环境具有较强的耐受力,金鱼藻、喜旱莲子草则多分布在中污染水域。水生植物对水环境变化敏感,结合水生植物对水质指示作用,表明长湖处于中污染～重污染状态。本次调查共鉴定出着生藻类81种,隶属于7门37属,其中蓝藻门14种,绿藻门22种,金藻门、黄藻门、裸藻门各1种,甲藻门3种,硅藻门17属39种。根据优势度(Y≥0.02)确定优势种,其中秋季7种,冬季8种,春季7种,夏季3种,其中钝脆杆藻、缘花舟形藻为四季共有优势种,针杆藻属、双眉藻属、小环藻属、菱形藻属、舟形藻属、异端藻属、桥弯藻属为四季共有属。菱形藻属、异端藻属为多污带指示种;舟形藻属为富营养化水体指示种,有着较宽的生态指示值范围;钝脆杆藻为重金属Cu的指示种;肘状针杆藻为重金属Zn的指示种。结合着生硅藻对水质指示作用,表明长湖处于富营养化状态,且对重金属Cu、Zn有一定指示作用。(4)高等水生植物与水环境因子的相关性分析:采用Pearson和RDA两种方法对高等水生植物与水环境因子进行相关性分析,结果表明,挺水植物芦苇、香蒲、喜旱莲子草与总磷、总氮、正磷酸盐具有正相关性,其中香蒲和总磷呈显著正相关;沉水植物菹草、金鱼藻和浮叶植物菱、荇菜与总磷、正磷酸盐具有正相关性,其中金鱼藻、荇菜与正磷酸盐呈显著正相关。芦苇和菱与水深、化学需氧量、p H、叶绿素a呈负相关,喜旱莲子草与悬浮物、透明度、溶解氧呈负相关。Pearson和RDA两种方法对高等水生植物与水环境因子的相关性分析结果趋于一致。(3)着生硅藻与水环境因子相关性分析:采用Pearson和RDA对着生硅藻与水环境因子进行分析,结果表明,梅尼小环藻与p H、总氮具有正相关性,缘花舟形藻、肘状针杆藻、缢缩异端藻、窗格平板藻、钝脆杆藻、线形圆筛藻、绿舟形藻、微细异端藻、帽形菱形藻与正磷酸盐、总磷、总氮、悬浮物具有正相关性,其中窗格平板藻、线形圆筛藻、缢缩异端藻与正磷酸盐呈显著正相关,帽形菱形藻与总氮呈显著正相关,缘花舟形藻与悬浮物呈显著正相关,帽形菱形藻、窗格平板藻、扁圆舟形藻与p H、溶解氧、化学需氧量呈负相关。Pearson和RDA两种方法对高等水生植物与水环境因子的相关性分析结果趋于一致。(6)高等水生植物与着生硅藻相关性分析:采用Pearson和RDA两种方法对高等水生植物与着生硅藻进行相关性分析,结果表明,扁圆舟形藻、微细异端藻、梅尼小环藻、钝脆杆藻、缘花舟形藻线形圆筛藻、帽形菱形藻与荇菜、喜旱莲子草、菹草、菱呈正相关,其中扁圆舟形藻、钝脆杆藻、窗格平板藻与喜旱莲子草呈显著正相关,线形圆筛藻、窗格平板藻、帽形菱形藻与菹草呈显著正相关,颗粒直链藻、钝脆杆藻、尖异端藻与芦苇、凤眼莲、莎草呈正相关,其中尖异端藻与芦苇、莎草呈显著正相关,绿舟形藻与香蒲、莲呈显著正相关,肘状针杆藻与芦苇呈负相关。芦苇、莲、香蒲、水蓼属于耐污种,多分布在重污染水域,喜旱莲子草属于中污染指示种,菹草为耐污种,多分布于重污染水域,荇菜、菱喜生活于高氮磷、浊度大的水域。梅尼小环藻对p H敏感,菱形藻属、异端藻属为多污带指示种,舟形藻属为富营养化水体指示种;钝脆杆藻为重金属Cu的指示种;肘状针杆藻为重金属Zn的指示种;桥弯藻属为β-中污染指示种。综合上述生物指示种结果表明,长湖处于β-中污染～重污染状态。Pearson和RDA两种方法对高等水生植物与水环境因子的相关性分析结果趋于一致。更多还原

【Abstract】 Located at the junction of Jingzhou,Qianjiang and Jingmen cities,Changhu lake has comprehensive functions of flood storage,navigation and irrigation.It is a typical eutrophic lake in the middle reaches of the Yangtze River and a national germplasm resource protection zone for large-mouth culter.According to relevant reports,the Lake was in a state of moderate eutrophication and severe eutrophication in some parts before the comprehensive defencing in 2016.After the defencing,the nutrient levels of N and P in The Lake showed a downward trend,and the water environmental pollution gradually improved.Higher aquatic plants and algae,as primary producers in aquatic ecosystem,are mutually restricted and can regulate water environmental factors.At the same time,they can also act as indicators in aquatic ecosystem and directly reflect the quality of water environment.In this study,14 water environment indexes,such as TN,TP,DO and COD,were monitored in October 2020(autumn),January 2021(winter),April 2021(spring)and July 2021 in Changhu Lake.The species composition,dominant species,biomass,diversity index(Shannon-Wiener index,Pielou evenness index,Margalef index)and other community structure characteristics of higher aquatic plants and diatoms were analyzed,and the comprehensive nutrient index(TLI)was analyzed for water environmental factors.Pearson correlation analysis and redundancy analysis(RDA)were used to analyze the correlation of higher aquatic plants,diatoms and water environmental factors in Changhu Lake.The results showed that:(1)Water environmental factors:The water quality of the lake was weakly alkaline throughout the year,and the average p H range was 8.09 to 8.34,with the highest value of 9.12 at C11 in winter.The annual average range of water temperature is8.08～32.32℃,and the average range in summer is 30.30～36.90℃,and the C13 sampling point is the highest(36.90℃).The dissolved oxygen level was higher all year round,with an average range of 11.79-13.60,with the lowest in summer(11.79)and the highest in winter(13.60).The average range of total nitrogen was 0.39-1.91,with the highest value in summer(1.91),the highest value in C12 sampling site(0.39),and the lowest value in autumn(0.39).The average range of total phosphorus was 0.03-0.23,with the highest value(0.23)in summer,the highest value(0.39)at sampling site C11,and the lowest value(0.03)in winter.According to the surface water environmental quality standard(GB3838-2002),the whole Lake is in classⅲ water state,and some sampling points are in class water state.ⅲ(2)Water Quality assessment:The analysis results of comprehensive nutrient index(TLI)of water environment factors in The Long Lake showed that the variation range of autumn,winter,spring and summer were 32.68-60.13,33.02-61.17,33.32-61.23 and 39.66-66.44,respectively,and the average annual TLI range was 33.12-61.76.The overall level of eutrophication was mild to moderate,and some sampling points were close to severe eutrophication.From the perspective of Shannon-Wiener index(H),the H value varies from 1.88 to2.64 in autumn,1.23 to 2.24 in winter,1.68 to 2.30 in spring,and 1.80 to2.32 in summer,all of which are in the β-medium pollution to α-medium pollution range.According to the Pielou evenness index(J),the J value varies from 0.44 to 0.94 in autumn and 0.46 to 0.91 in winter,which are light pollution to α-medium pollution.The range is 0.72～0.90 in spring and0.63～0.86 in summer,both of which are light pollution ～β-medium pollution.According to Margalef index(D),the D value in autumn ranges from 2.04 to3.68,which belongs to the level of light pollution ～β-medium pollution.In winter,it is 1.84～2.49,which is β-medium pollution ～α-medium pollution level.In spring,it is 1.92～3.08,which is light ～α-medium pollution level.In summer,it is 2.03～4.17,which is light pollution ～β-medium pollution level.According to the above index analysis results,the water quality of Long Lake is in β-medium pollution ～α-medium pollution level.(3)Analysis of community structure characteristics of higher aquatic plants and symbiotic diatoms:A total of 24 species of 20 families,19 genera and 24 species of higher aquatic plants were identified in this survey,including 8 families,7 genera and 8 species of emergent plants,3 families,3 genera and 3 species of floating plants,4 families,4 genera and 6 species of floating plants,and 3submerged plants.3 genera and 7 species.According to the important values,a total of 7 flora clusters of higher aquatic plants in Changhu Lake are determined,namely reed + lotus + eucalyptus,water hyacinth,reed +eucalyptus,reed,sedge grass,water chestnut,reed + polygonum+ lotus.Reed,cattail,and thorn grass are pollution-tolerant species,and are mostly distributed in heavily polluted waters.Water chestnut and water chestnut have strong tolerance to high concentrations of N and P in the water environment.polluted waters.Aquatic plants are sensitive to changes in the water environment,and combined with the indication of aquatic plants on water quality,it shows that Changhu Lake is in a state of moderate to heavy pollution.A total of 81 species of living algae were identified in this survey,belonging to 7 phyla and 37 genera,including 14 species of Cyanobacteria,22 species of Chlorophyta,1 species of Chrysophyta,Xanthophyta,Euglenophyta,and 3 Dinophyta There are 17 genera and 39 species of Diatoms.The dominant species were determined according to their dominance(Y≥0.02),including 7 species in autumn,8 species in winter,7species in spring,and 3 species in summer.The genus Dimensium,Cyclotella,Rhodophyta,Navicula,Heresy,and Bridgetonia are the four-season common genera.Rhodophyta and Heretotheca are indicator species for multi-pollution zones;Navicula is an indicator species for eutrophic water bodies,with a wide range of ecological indicators;C.blisteris is an indicator species for heavy metal Cu;Acupuncture sp.It is the indicator species of heavy metal Zn.Combined with the indication effect of raw diatoms on water quality,it shows that Changhu Lake is in a state of eutrophication,and has a certain indication effect on heavy metals Cu and Zn.(4)Correlation analysis between higher aquatic plants and water environmental factors:Pearson and RDA methods were used to analyze the correlation between higher aquatic plants and water environmental factors.The results showed that phragmites australis,Typha cattails and xerophilous lotus seed were positively correlated with total phosphorus,total nitrogen and phosphate,and typha cattails and total phosphorus were significantly positively correlated.Such species had positive correlation with total phosphorus and orthophosphates,among which,such species had significant positive correlation with orthophosphates.The correlation analysis results of Pearson and RDA for higher aquatic plants and water environmental factors tended to be consistent.The results showed that reed and RDA were negatively correlated with water depth,chemical oxygen demand(COD),p H and chlorophyll A,and drought-tolerant Lotus seed was negatively correlated with suspended matter,transparency and dissolved oxygen.(3)Correlation analysis between diatoms and water environmental factors:Through Pearson and RDA analysis of diatom and water environmental factors,the results showed that There was a positive correlation between p H and total nitrogen of C.meniensis.Edge flower boat shape algae,elbow needle bar algae,constriction heresy,pane tablet,blunt brittle pole algae,linear circular sieve algal algae,green boat shape,fine heresy algae,cap shape diamond and orthophosphate,there was a positive correlation between total phosphorus,total nitrogen,suspended solids,including pane tablet algae,linear sieve algal,constriction heresy and orthophosphate was significantly positively related to cap shape diamond algae and was significantly positively related to total nitrogen,There was a significant positive correlation between THE p H,dissolved oxygen and chemical oxygen demand(COD)of THE rhodophyllum,phaeophyllum and rhodophyllum were negatively correlated with suspended matter.The correlation analysis results of Pearson and RDA for higher aquatic plants and water environmental factors tended to be consistent.(6)Correlation analysis between higher aquatic plants and diatoms:This study analyzed the correlation between higher aquatic plants and diatoms using Pearson and RDA methods,and the results showed that there was a positive correlation between nymphoides,heterozygopsis microphylla,Cymophyllum meniensis,Spirometria punctatum,Rhodophynopsis cappelaris,crispus pontoides,and Water lily.Flat boat shape algae,blunt brittle pole algae,pane tablet algal xerophilous lotus seed grass was significantly positively related,linear circular sieve algal,pane tablet algae,cap shape diamond was significantly positively related to algal and Zu grass,grain amylose,blunt brittle pole algae,pointed heresy algal positively correlated with reeds,crassipes,sedges,algae which pointed a heresy and significant positive correlated to the reeds,sedges,There was a significant positive correlation between P.sinensis and cattail and Lotus,and a negative correlation between P.cubitus and Phragmites australis.Reed,lotus,cattails,and water piper belong to pollution resistant species,mostly distributed in heavily polluted waters.Drought-loving lotus seed grass belongs to medium pollution indicator species,crispus pelton is pollution resistant species,mostly distributed in heavily polluted waters,and water lily prefers to live in water with high nitrogen and phosphorus content and turbidity.Chlorella meniensis was sensitive to p H,rhombozygophyta and Heterozygophyta were the indicator species of many pollution zones,and Bogophyta was the indicator species of eutrophic water bodies.The species of The heavy metal Cu was amelopecia SPP.Stipa elanguformis is an indicator species of heavy metal Zn.The genus Cambrium is a β-medium pollution indicator species.The results showed that the lake was in β-medium-heavy pollution state.The correlation analysis results of Pearson and RDA for higher aquatic plants and water environmental factors tended to be consistent.更多还原