Gehu Lake Research Articles

Development and testing of the phytoplankton biological integrity index (P-IBI) in dry and wet seasons for Lake Gehu

Taking Lake Gehu located in the Yangtze River Delta as the research object, the phytoplankton community and environmental variables at 18 sampling sites in Lake Gehu were monitored and investigated during the dry season (March) and the wet season (July) of 2020. On this basis, the phytoplankton biological integrity index (P-IBI) was established during dry and wet periods, and the health of the lake water ecosystem was evaluated. The results showed that the P-IBI in dry and wet periods was consistent throughout Lake Gehu, and the overall water ecological health assessment results were “moderate”. To test the stability of the P-IBI, the relationships between the P-IBI, its constituent parameters and a single water quality environmental factor were analyzed through redundancy analysis (RDA). The results showed that total nitrogen, the hypermanganate index, chlorophyll a, dissolved oxygen, ammonia nitrogen, and transparency were highly correlated with the P-IBI system. Comparing the composition of the P-IBI during dry and wet periods and the relationships between the P-IBI system and water quality factors in the two hydrological periods, it was found that the parameters of the P-IBI system differed greatly between the dry and wet periods. The number of significantly related water quality factors in the dry period was greater than that in the wet period, and the two-axis characteristic values, the correlations between the P-IBI system and the water quality factors, and the cumulative percentage of the dry period were higher than those in the wet period. In conclusion, the P-IBI exhibits temporal variation between hydrological periods, and the stability of the P-IBI evaluation system during the dry season is significantly better than that during the wet season.

The effects of water depth on the growth of two submerged macrophytes in an in situ experiment

An in situ experiment was designed in which Potamogeton crispus and Hydrilla verticillata were planted in plastic pots 25, 50, 75, 100, 125, 150, 175 and 200 cm underwater to study the effect of water depth on the growth and photosynthetic fluorescence characteristics of the two submerged macrophytes in Lake Gehu, China. The results showed that: 1) Water depth had no significant effect on the germination of both submerged macrophytes. The final germination rate of P. crispus turions was higher than 80%, and the final germination rate of the H. verticillata winter buds was 100%; 2) Water depth affected the survival rate of both submerged macrophytes, and the seedlings at depths of 150, 175 and 200 cm all eventually died; 3) Water depth altered the morphological characteristics of P. crispus and H. verticillata seedlings. (4) Increasing water depth significantly affected biomass (p < .05), with the biomass initially tending to increase, but then decreasing. The root to shoot ratio of both submerged macrophytes decreased with increasing water depth; 5) Chlorophyll contents of P. crispus and H. verticillata increased with water depth from 25 to 150 cm; 6) Water depth had an obvious effect on the photosynthetic fluorescence of submerged macrophytes. The Fv/Fm increased slightly from water depths from 25 to 75 cm, and then decreased significantly when water depth exceeded 100 cm. The ETRmax was significantly different among all treatment groups, and ETRmax was obviously higher at water depths of 25 and 50 cm than at all other depths. These results showed that submerged macrophytes have a limited water depth tolerance range. In Lake Gehu, the recovery of submerged macrophytes will be better in areas with water depths less than 125 cm.

Characterizing chromophoric dissolved organic matter in Lake Gehu, Lake Dianshan and Lake Yangcheng in different hydrological seasons

长三角地区大部分湖泊为非通江湖泊，地势低平，港汊及闸坝众多，水流宣泄不畅，水力滞留时间较长，加之周边地区城镇人口稠密.因此与水滞留时间短的通江湖泊相比，非通江湖泊的有色可溶性有机物（CDOM）来源和组成具有差异性.本文选取了3个重要的中型非通江供水湖泊——滆湖、淀山湖和阳澄湖，对枯水期、平水期、丰水期3种水文情景下CDOM组成结构变化特征进行分析，从而进一步揭示该类湖泊CDOM来源和对水文情景响应的内在机理.结果表明：滆湖、淀山湖和阳澄湖通过平行因子分析法得到2种类腐殖质（C1和C4）和2种类蛋白质（C2和C3），湖泊CDOM结构受到降雨事件和人类活动的双重影响.三个湖泊类蛋白质的高值在空间上主要集中在人类活动频繁的湖区，并且类蛋白质平均荧光强度与叶绿素a浓度相关性较差，说明湖泊类蛋白质组分受到内源藻类降解、外源人类生产生活排放双重作用的影响.三个湖泊类蛋白质的平均荧光强度和总氮浓度均在枯水期显著高于丰水期，说明降雨量的增加可以稀释湖泊有机质浓度；同时，陆源类腐殖质C1与溶解性有机碳、总氮、总磷、叶绿素a浓度呈显著正相关，并且随着降雨量增加，类蛋白质的占比逐渐降低，滆湖从86.84%降低至62.49%，淀山湖从96.53%降低至90.56%，阳澄湖从98.40%降低至96.26%，说明降雨事件也可以增强径流的冲刷作用，携带更多腐殖化程度高的陆源有机质进入湖泊.本研究发现降雨过程和人类活动共同作用于滆湖、淀山湖和阳澄湖CDOM库，研究结果可以为进一步保障太湖流域人类用水安全提供参考依据.

Spatial distribution and pollution assessment on the main nutrients and heavy metals in sediments of Lake Gehu, Taihu Basin after removing the aquaculture net&lt;sup&gt;*&lt;/sup&gt;

为评估滆湖围网拆除工程实施效果，采用高密度网格化布点方法，系统分析滆湖沉积物营养盐和重金属的空间分布和污染特征；并基于有机氮评价方法、综合污染指数评价方法、重金属地质累积指数法和重金属潜在生态风险评价方法进行污染风险评价.结果表明，滆湖沉积物总氮（TN）、总磷（TP）和总有机碳（TOC）的平均含量分别为（3709±1004）mg/kg、（1127±650）mg/kg和（78.39±23.88）mg/g，三者空间分布特征较为一致；营养盐综合污染指数评价表明，全湖整体为重度污染，其中全湖TN均处于重度污染状态，TP绝大部分区域也处于重度污染状态.沉积物重金属Zn、Cr、As、Pb、Ni、Cu、Cd的平均含量分别为（170.62±47.25）、（105.18±34.91）、（68.55±10.86）、（52.43±14.73）、（44.04±11.93）、（42.57±12.43）、（1.55±1.06）mg/kg，整体上呈现出由南向北、自西向东逐渐增加的趋势，重金属含量最高值在湖区东北角；地积累指数法和潜在生态风险指数法评价结果均表明Cd和As是主要的生态风险贡献因子，其中Cr和Ni的污染程度表现为清洁，Cr、Ni、Cu、Zn和Pb的单项潜在生态风险等级表现为轻微风险.与围网拆除前比，湖中区西南部沉积物营养盐含量无显著变化，湖南区南部沉积物营养盐状况明显改善，但其余各区域沉积物营养盐状况均有不同程度的恶化；湖区沉积物中重金属元素平均含量均有极大程度的降低，降幅在29.50%~80.45%之间，表明在外源污染输入得到一定控制时，围网拆除在控氮、控磷效果及改善重金属污染状况方面有着积极作用.;In this study, the spatial distribution characteristics of the main nutrients and heavy metals in sediments of Lake Gehu after completely removing the aquaculture net were investigated using high-density sampling methods, and their potential ecological risks were assessed based on organic nitrogen index, integrated pollution index, geo-accumulation index (I_geo) and potential ecological risk index. Results showed that the average contents of TN, TP and TOC were (3709±1004) mg/kg, (1127±650) mg/kg and (78.39±23.88) mg/g, respectively. The spatial distribution characteristics of TN, TP and TOC were relatively consistent, generally, those of the middle and upper part of the lake was higher than those of the southern part except the northern. Integrated pollution index showed that the whole lake was heavily polluted, meanwhile, the lake-was severely TN-polluted and slightly TP-polluted in most areas. The average contents of heavy metals Zn, Cr, As, Pb, Ni, Cu and Cd were (170.62±47.25), (105.18±34.91), (68.55±10.86), (52.43±14.73), (44.04±11.93), (42.57±12.43) and (1.55±1.06) mg/kg, respectively. Generally, the heavy metal contents increased from south to north, from west to east, and reached the highest level in the northeast corner. I_geo and the potential ecological risk assessment indicated that Cd and As were the most polluted elements and led to high potential ecological risk. According to the result of I_geo, Cr and Ni were not polluted, while Cr, Ni, Cu, Zn and Pb were at a slight potential ecological risk. Since the aquaculture net was being demolished, there was no significant change in the nutrient content in the southwestern part of the lake, and the nutrient status in the southern end of the Gehu Lake area was significantly improved, but the nutrient status in the rest of the area had deteriorated to varying degrees; the heavy metal content has a great reduction, ranging from 29.50% to 80.45%, indicating that when the input of external pollution is controlled to a certain extent, the removal of the fence has a positive effect on the effect of controlling nitrogen and phosphorus and improving the pollution of heavy metals.

Occurrence, source and ecotoxicological risk assessment of pesticides in surface water of Wujin District (northwest of Taihu Lake), China

This study investigated the occurrence and distribution of pesticides in surface water (lakes, major rivers and tributaries) and potential discharge sources (fish ponds, livestock and poultry farms, and sewage treatment plants) in Wujin District (northwest of Taihu Lake), Jiangsu province, China. An analytical liquid chromatography-tandem mass spectrometry method was developed for 38 pesticides, which was applied in the monitoring of 240 surface water samples and 76 potential discharge source samples. Eleven insecticides and five fungicides with temporal and spatial variation were detected in surface water. The total pesticide concentrations in surface water in different seasons were as follows: March > August > June > November. The two most polluting and widespread pesticides were carbendazim (maximum concentration 508 ng L−1, detection rate 100%) and imidacloprid (maximum concentration 438 ng L−1, detection rate 88%). Gehu Lake (S46) and Sanshangang River (S12) were seriously polluted water bodies. Seven insecticides and four fungicides were detected in the potential discharge sources; and their composition changed significantly with the seasons. The concentrations of detected organophosphorus pesticides and neonicotinoids (e.g. acetamiprid in March and dichlorvos in November) in a few non-agricultural planting sources were far greater than those detected in surface water, and hence a few fish ponds, livestock and poultry farms, and sewage treatment plants might be the potential discharge sources of pesticides in the surrounding surface water. The estimated input flux of the studied pesticides from upstream rivers to Taihu Lake was 141.95 kg a−1. Furthermore, more attention should be paid to the medium or high aquatic ecotoxicological risk presented by the levels of organophosphorus pesticides, carbamates, and benzimidazoles.

Regime shifts in shallow lakes observed by remote sensing and the implications for management

Abstract Shallow lakes are one of the most complex aquatic systems and are known to shift between a macrophyte-dominated clear-water state and a phytoplankton-dominated turbid state. We developed a decision-tree classification based on the normalized difference vegetation index (NDVI) to classify the major vegetation cover types in shallow lakes and documented the vegetation in Gehu Lake using Landsat time series images from 1984 to 2018. The area of aquatic vegetation in Gehu Lake (a large shallow lake in China) showed a significant decreasing trend (R2 = 0.839, p

Integrating multi indices for identifying priority management areas in lowland to control lake eutrophication: A case study in lake Gehu, China

Best management practices (BMPs) for controlling non-point sources (NPS) nutrient loss at the watershed scale has become a global hotspot due to the severe eutrophication worldwide. Identifying priority management areas (PMAs) is particularly important for designing BMPs. However, such an endeavor is extremely challenging due to random spatio-temporal processes, particularly in lowland. In this study, a new model-based method was proposed to identify sensitive areas with the largest contribution to lake eutrophication. This method integrated three indices derived from three models to assess the risk due to nutrient dynamics in loss processes including sources, sinks and transformation of nutrients within the polders (lowland artificial watersheds) around Lake Gehu, eastern China and nutrient transport in the river and lake areas. A total of 67 polders in a 2 km wide buffer of Lake Gehu, as assessment units, were identified into four-level PMAs based on the integration. Results showed that 77% polders were Level II PMAs, and none were Level IV PMAs. The ratios of Level I and Level III PMAs was 18% and 5%, respectively. These values indicated that nutrient transport in rivers or lakes is vital for lake eutrophication and significantly influences the PMA map. This study demonstrated that the process-based model for risk assessment in identifying PMAs is useful in guiding decision-making for controlling lake eutrophication.

Characteristics and its influencing factors of suspended solids distribution in Lake Gehu, Taihu Basin

基于2018—2019年的周年调查，分析了滆湖总悬浮物（TSS）的时空分布特征、组成及其季节变化规律，并探讨了水体悬浮物的影响因素及其与氮、磷的关系.结果表明：（1） TSS浓度的年内变化范围在11.80~105.87 mg/L之间，平均浓度为41.87±18.09 mg/L.（2）滆湖水体TSS时空差异显著.空间上呈现高速公路以南湖区（B区）大于高速公路以北湖区（A区），沿岸高于湖心区的分布趋势；季节变化整体表现为：夏季 > 秋季 > 春季 > 冬季，且夏季显著高于其他季节.（3）滆湖水体中无机悬浮物（ISS）和有机悬浮物所占TSS的比例差异悬殊，分别为75.5%和24.5%，A区和B区均以ISS为主.（4）线性拟合表明，TSS与颗粒态氮、总磷和颗粒态磷具有极显著正相关关系；（5） TSS与叶绿素a浓度相关性极显著.综合结果分析，藻类暴发和泥沙再悬浮是影响滆湖水体悬浮物浓度的重要因素.;The spatial-temporal distribution characteristics, composition and its change rule of different seasons of total suspended solids (TSS) in Lake Gehu, were analyzed by annual investigation in 2018-2019. The key impacting factors of TSS and relationship between it and nitrogen, phosphorus were discussed. The results showed that the annual variation of TSS concentration ranged from 11.80 to 105.87 mg/L, and the average concentration was 41.87±18.09 mg/L. The temporal and spatial differences of TSS in Lake Gehu were significant. The spatial distribution trend of the lake area south of the highway (B area) was larger than that of the lake area north of the highway (A area), and the coastal area was higher than the central area. As a whole, the seasonal change was manifested as summer > autumn > spring > winter, and summer was significantly higher than other seasons. The proportions of inorganic suspended solids (ISS) and organic suspended solids (OSS) in TSS of the whole lake body were significantly different, with the value of 75.5% and 24.5%, respectively. Both area A and area B was dominated by ISS. Linear fitting showed that TSS had extremely significant positive correlation with particulate nitrogen, total phosphorus and particulate phosphorus. The correlation between TSS and chlorophyll-a was also significant. Based on the above analyses, algal blooms and sediment resuspension were important factors affecting the concentration of suspended solids in water.

Antibiotic resistance genes in lakes from middle and lower reaches of the Yangtze River, China: Effect of land use and sediment characteristics

Freshwater lakes provided an ideal media for the accumulation and propagation of antibiotic resistance genes (ARGs), because they were susceptible to anthropogenic impacts. Land reclamation and urbanization exerted severe anthropogenic impacts on lakes from middle and lower reaches of the Yangtze River, China over the past decades. In this study, 15 lakes in the region were selected to understand the level and variability of ARGs. Proportion of different land use types was applied to display the land reclamation and urbanization around each lake. For sulfonamide resistance (sul) genes, sul1 had the highest relative abundance in sediments, with maximum 2.11 × 10−1 copies/16SrRNA copy in Gehu Lake. For tetracycline resistance (tet) genes, tetG had the highest average value of relative abundance (4.74 × 10−3 copies/16SrRNA copy), followed by tetB, tetA, tetQ and tetM. Class I integron (intI1) played an important role in acquisition and dissemination of sul1 and tetG. Sediment characteristics (moisture, density, total nitrogen, total carbon, ammonium, and nitrate) were found to have no significant effect on ARG distribution. Taihu Lake and Yangcheng Lake which exhibited high sul and tet genes had the high proportion of built-up land use.

Restoration in northern Lake Gehu, a eutrophic lake in China

Lake Gehu is a severely eutrophic lake in southeast China. A series of restoration measures have been implemented since 2009 in northern Lake Gehu. This study compared aquatic plants, water quality, sediment, and phytoplankton between restoration and control areas to investigate the effect of restoration measures. The results demonstrated that aquatic macrophyte coverage increased from 0% to 10.6%; mean TP, TN, and CODMn concentrations increased by 50.0%, 42.4%, and 40.8%, respectively, compared with those before the measures were carried out; the mean Secchi depth (SD) increased to 42.5 cm, which is 1.4 times higher than that before restoration; the mean euphotic depth (Zeu) in the summer increased from 91 to 130 cm; the mean chl a concentration decreased from 34.8 to 20.2 μg/L, compared with that before restoration; the Shannon-Wiener index of phytoplankton increased by 28.7%. The mean TP and TN concentrations in sediments decreased by 63.8% and 52.4%, respectively, compared with that before dredging. These results indicate that the restoration in northern Lake Gehu was effective. To complete the transformation from an algae- to a macrophyte-stable state within the region, further measures must be adopted. This restoration of a eutrophic lake can serve as a reference for similar eutrophic lakes.

Community structure of macrozoobenthos and its relationship with environmental factors in Lake Gehu, Jiangsu, China.

A survey on macrozoobenthos was conducted seasonally and 14 aquatic physicochemical parameters were monitored monthly to reveal the community characteristics of macrozoobenthos and their relationship with aquatic environmental factors at 20 sampling sites in the Lake Gehu from July 2013 to December 2014. A total of 25 macrozoobenthos species including 3 species (12% of total) of Mollusca, 12 species (48%) of Chironomidae, 4 species (16%) of Oligochaeta, 4 species (16%) of Crustacean were identified. The dominant species were Limnodrilus hoffmeisteri, Branchiuras owerbyi, Tanypus chinensis, and Propsilocerus taihuensis. Density and biomass of Chironomid larvae and Oligochata had significant spatial and seasonal changes. The state of aquatic environment was mainly affected by the nitrogen, phosphorus and water temperature in the Lake Gehu, and TN, NO3--N and DO changed significantly with space and season. The Spearman correlation analysis indicated that TN and NO3--N played a key role in the community structure characteristics of the macrozoobenthos in the Lake Gehu. The environmental variables could well explain the changes of main macrobenthic species.

Occurrence characteristics and bioavailability of heavy metals in surface sediments of Lake Gehu, Taihu Basin

Occurrence characteristics and bioavailability of heavy metals in surface sediments of Lake Gehu, Taihu Basin

Spatio-temporal distribution of phytoplankton and environmental factors in the north part of Lake Gehu(Jiangsu) after muti-treatment

Lake Gehu is a representative shallow lake located in the downstream of Yangtze River in China. To identify the phytoplankton community distribution after its treatment,a survey was conducted on the phytoplanktonic community and environmental factors in its north part from January to December in 2013. According to the survey,there were altogether seven phylum,fourtythree genus and sixty-one species of phytoplankton,mainly with Scenedesmus and Cyclotella in spring and winter,Microcystis and Melosira granulata in summer and autumn. The maximum phytoplankton biomass during sampling period was 90. 6 mg / L in August,mainly with Microcystis aeruginosa. The average density of phytoplankton showed a decreasing trend from west to east,with lower vegetation coverage in the open water area. The environmental factor analysis indicated that total nitrogen,total phosphorus and water temperature were key factors that influence the phytoplanktonic density and biomass in this area. Comparing with the average biomass in the water chestnut area and reed area with that in the untreated open water area in the same month,we found that the water chestnut area decreased with the range of 72. 7%-91. 1%,and 63. 9%-83. 7% in the reed area. In August and September when algal bloom occurred in the open water area,the biomass in the chestnut area and in the reed area was only 14. 6% and30. 3% of that in the water area,respectively.

Optical properties after multi-treatments in northern part of Lake Gehu, Jiangsu Province in summer

选取滆湖为研究对象,探究这一开放水体的北部湖区水体光环境是否有利于沉水植物的恢复.通过对整治后的2013年夏季(7月和8月)滆湖北部整治湖区(A湖区)和临近未整治区(B湖区)水体光环境的监测,发现在夏季7月A湖区透明度(SD)平均达39cm,显著高于B湖区,同时7月A湖区SD较8月高.夏季悬浮物和叶绿素a(Chl.a)是影响水体光环境的主要因子.7月两个湖区无机悬浮物的浓度差异是造成SD和K_d差异的原因;7月与8月A湖区Chl.a的浓度差异,是造成A湖区两个月份水体光环境差异的主要因素.与整治时(2009年)相比,7月水体光环境显著提高.整治后A湖区水深的显著增加,在一定程度上不利于沉水植物的恢复.;IIn order to investigate whether the optical properties were benefit for the restoration of submerged plants in an open water in the northern of a shallow lake, Lake Gehu, we measured the influence factors of the underwater light environment in the areas which were with and/or without multi-treatments(area A and area B) in July and August, 2013. The results showed that the average secchi disk depth(SD) was 39cm in July in area A, which was much higher than that in area B. The SD in July was also higher than that in August in area A. Suspended solids and chlorophyll-a(Chl.a) were the main factors of optical properties in summer. The significant difference of SD and K_d between the two areas in July was caused by the difference of inorganic suspended solids in two areas. The optical properties in area A also had a significant difference between July and August in 2013, which was caused by the remarkable differences of Chl.a concentration in the two months. The underwater light environment of area A has improved significantly in July, compared with 2009 when it was under treatment. It will not benefit the restoration of submerged plants in area A as the depth has increased a lot.

Characteristics of Organic Phosphorus in a Shallow Lake Gehu investigated by Sequential Fractionation and 31P-NMR Technicals

Organic phosphorus in sediments of lake Gehu in China was investigated and researched via two methods: chemical fractionation and phosphorus-31 nuclear magnetic resonance spectroscopy. Results of chemical fractionation suggested that concentration of each organic phosphorus species in different sediments may varied highly since different condition, but showed a rank trend : residual Po&gt; HCl-Po&gt; Fulvic-Po&gt; Humic-Po&gt;NaHCO3-Po. Labile and moderately labile Po , regarded as potential P , contributed to 33.6% to 64.6% relative to total Po, which can be degraded for phytoplankton. 31P-NMR results suggested that the rank order of P species presented in NaOH-EDTA extractants of sediments: orthophosphate&gt; monoester-P&gt; DNA-P&gt; pyrophosphate-P, and polyphosphate and phosphonate were almost not detected.

Preliminary study on the optical properties of Lake Gehu

基于2009年7月至2010年6月滆湖全湖15个采样点的水体光学参数及相关水质理化因子数据,分析滆湖水体周年光合有效辐射(PAR)衰减特性,以期为滆湖沉水植物生态修复提供相关水体光学资料.结果表明,滆湖水体PAR衰减系数(K_d)周年变化范围为1.32~17.42 m^-1.秋季K_d相对最小,平均值为2.35 m^-1,变化范围为1.32~3.70 m^-1;夏季K_d相对最大,平均值为6.23 m^-1,变化范围为3.68~17.42 m^-1.春、秋、冬季,滆湖水体真光层平均深度均满足沉水植物的生长需求,而在夏季滆湖水体真光层平均深度仅为0.84 m,小于全湖平均水深(1.20 m),因此夏季PAR是限制沉水植物恢复的因子之一.滆湖水体K_d与透明度(SD)在秋、冬季的关系为:K_d=2.089+0.705/SD.叶绿素a浓度和悬浮物浓度是影响滆湖水体K_d的重要因子之一.;Seasonal variations of the optical parameters and physicochemical properties of lake water at 15 sampling sites were investigated, from July 2009 to June 2010, to provide the basic lake optical properties data for submerged aquatic vegetations restoration of a shallow lake-Lake Gehu. The annual variation of the attenuation coefficient of photosynthetically active radiation (K_d) was 1.32-17.42 m^-1. The minimum and maximum values of K_d were observed in autumn (1.32-3.70 m^-1) and summer (3.68-17.42 m^-1), with a medium value of 2.35 m^-1 and 6.23 m^-1, respectively. The average euphotic zone depth in spring, fall and winter can satisfy the demand of submerged aquatic vegetation. However, the average euphotic zone depth was only 0.84 m in summer, which was less than the average water depth(1.20 m) of Lake Gehu and implied that the photosynthetically active radiation was one of the inhibiting factors to restore the submerged aquatic vegetations in summer. The K_d and secchi disk depth (SD) in fall and winter had the relationship of K_d=2.089 + 0.705/SD. Chlorophyll-a and suspended solid were the factors influencing the K_d value in Lake Gehu.

Industrial and agricultural effects on water environment and its optimization in heavily polluted area in Taihu Lake Basin, China

The deteriorating water quality in the Taihu Lake Basin has attracted widespread attention for many years, and is correlated with a sharp increase in the quantity of pollutant discharge such as agricultural fertilizers and industrial wastewater. In this study, several factors were selected for evaluating and regionalizing the water environmental capacity by ArcGIS spatial analysis, including geomorphologic characteristics, water quality goals, water body accessibility, water-dilution channels, and current water quality. Then, the spatial optimization of agriculture and industry was adjusted through overlay analysis, based on the balance between industrial space and water environmental capacity. The results show that the water environmental capacity gradually decreases from the west to the east, in contrast, the pollution caused by industrial and agricultural clustering is distributes along Taihu Lake, Gehu Lake and urban districts. The analysis of the agricultural space focuses on optimizing key protected areas of the Taihu Lake Basin, and the shores of Gehu Lake, optimally adjusting the second protected areas of the Taihu Lake Basin, and generally adjusting the urban areas of Changzhou and Wuxi cities. The analysis of industrial space focuses on optimizing the downtowns of Changzhou and Wuxi cities, optimally adjusting key protected areas and second protected areas of the Taihu Lake Basin, and generally adjusting the south and southwest of Gehu Lake. Lastly, some schemes of industrial and agricultural layouts and policies for the direction of industrial and agricultural development were proposed, reflecting a correlation between industry and agriculture and the water environment.

Photosynthetic activity of phytoplankton in Lake Gehu and Lake Luoma in spring

本研究应用Phyto-PAM荧光仪测定滆湖和骆马湖春季浮游植物的光合活性,包括浮游植物最大光量子产量Fv/Fm(可变荧光与最大荧光之比)、有效光量子产量Φ_PSII(实际光合作用效率)和快速光响应曲线(RLC);同时,采用显微镜对浮游植物进行镜检和计数.结果表明:滆湖蓝藻和硅藻的最大光量子产量分别为0.36~0.52和0.27~0.53,实际光量子产量分别为0.25~0.37和0.25~0.36,没有检测到绿藻的光合活性,RLC曲线表明蓝藻有较高的光合作用效率,更易形成优势种群;骆马湖绿藻和硅藻的最大光量子产量分别为0.45~0.65和0.41~0.49,实际光量子产量分别为0.25~0.32和0.19~0.25,没有检测到蓝藻的光合活性;滆湖浮游植物丰度在530×10⁴~4200×10⁴cells/L之间,平均值为2918×10⁴cells/L,群落组成以蓝藻门、硅藻门、隐藻门和裸藻门为主;骆马湖浮游植物丰度在260×10⁴~510×10⁴cells/L之间,平均值为379×10⁴cells/L,群落组成以硅藻门和绿藻门为主.综合滆湖和骆马湖水体的营养水平、浮游植物丰度和光合作用活性表明,湖泊富营养化能提高浮游植物种群丰度和蓝藻的光合作用活性,进而有利于蓝藻在浮游植物群落中占有竞争优势.;In the present study,Phyto-PAM was applied to measure maximal photochemical quantum yield of PSII (Fv/Fm), actual photochemical efficiency of PSII (Φ_PSII),and rapid light response curve (RLC) of phytoplankton samples collected from Lake Gehu and Lake Luoma in spring.Meanwhile,the cell numbers of phytoplankton were counted by microscopy.The results showed that values of Fv/Fm and Φ_PSII of cyanobacteria in Lake Gehu varied from 0.36 to 0.52 and from 0.27 to 0.53,and Bacillariophyta, from 0.25 to 0.37 and from 0.25 to 0.36,respectively,but there was no photochemical vitality of Chlorophyta.RLC has indicated that cyanobacteria has higher photochemical vitality and are prone to form advantage populations in Lake Gehu.On the other hand,the values of Fv/Fm and Φ_PSII of Chlorophyta and Bacillariophyta in Lake Luoma ranged from 0.45 to 0.65, from 0.41 to 0.49,from 0.25 to 0.32,and from 0.19 to 0.25,respectively,and no photochemical vitality were found for cyanobacteria.The density of phytoplankton in Lake Gehu ranged from 530×10⁴ to 4200×10⁴ cells/L,with an average of 2918×10⁴ cells/L.Cyanophyta,Bacillariophyta,Cryptophyta and Euglenophyta were dominant in the phytoplankton community.The density of phytoplankton in Lake Luoma varied from 260×10⁴ to 510×10⁴ cells/L,with an average of 379×10⁴ cells/L,Bacillaryophyta and Chlorophyta were dominant in the phytoplankton community.According to the comparison between nutritional level,the abundance and photochemical vitality of phytoplankton assemblages in the two lakes,the lake eutrophication can increase the abundance of phytoplankton and photosynthetic activity of cyanobacteria,and become in favor of gaining advantages in phytoplankton assemblages.

The influences of silver carp and bighead carp in bio-manipulation pen on the community structure of cladocera in Lake Gehu

As a dominant group of zooplankton in fresh water worldwide,Cladocera plays an important role in the material circulation and energy flow of water ecosystem,and it is not only a consumer for small animals and algae,but also food for zooplanktivorous fish.Many current studies have showed that non-classical bio-manipulation,a way to prevent water bloom and improve water environment by controlling fierce fish and stocking planktonivorous filter-feeding fish(such as Hypophthalmichthys molitrix and Aristichys mobilis),can be effective.However,to some extent,phytoplankton and community structure of cladocera may be varied with different stocking patterns,fish density and lake type.Lake Gehu,a total area of 164 km2 crossing Wujin and Yixing,is located in the south of Jiangsu province.In recent years,more attention was paid to the researches about the influence of H.ypophthalmichthys molitrix and Aristichys mobilis on lake ecosystems,of which the past domestic studies were mainly focused on aquatic plants,physical and chemical factors,the control of eutrophication and phytoplankton,however,no reports have been made in the bio-manipulation fish pen of Lake Gehu about the influences of abiotic environmental factors and filter-feeding fish on cladocera,and that is our work to fill in the blanks.Thus,from December 2009 to November 2010,a large bio-manipulation fish pen with the stock of silver carp(H.molitrix)and bighead carp(A.mobilis)inside was built to control the cyanobacterial bloom in Lake Gehu,an investigation and laboratory analysis was carried out to compare the variation of the cladoceran community structure between region A outside of the fish pen and regions B,D,C with different ratios of fish(1∶ 4,1∶ 2,1∶ 1.5),which was combined to discuss the influences of bio-manipulation fish pen on cladocera and the effects on improving eutrophic water.Through the identification,32 species of cladocera,belonging to 7 families,14 genera were collected inside and outside of the fish pen where there were no differences between species,and the annual average density and biomass of region A were both higher than any region inside of the fish pen,having a significant difference(P0.05)with region B,respectively.The main dominant species were Bosmina longirostris,Ceriodaphnia cornuta and Moina sp..In August,the density of Moina sp.in region A had significant differences from region B and D,while 3 regions inside of fish pen had no apparent differences,et al.,the results of which indicated that Moina sp.with a larger volume was easier to be preyed by fish than the other two small species.Moreover,some characteristic parameters of water were investigated to depict the correlation between cladoceran and environmental variables.CCA(Canonical Correspondence Analysis)showed that water temperature,permanganate index(CODMn),nitrate nitrogen(NO3-N)and water transparency(SD)were the main abiotic factors affecting the community structure of cladocera.

Genetic variation analysis of yellow catfish (&lt;i&gt;Pelteobagrus fulvidraco&lt;/i&gt;) from five lakes in the middle and lower reaches of the Yangtze River based on Mitochondrial DNA cyt &lt;i&gt;b&lt;/i&gt;

对长江中下游5个湖泊的黄颡鱼种群的线粒体DNA细胞色素b基因进行了PCR扩增、测序,获得了955 bp的序列.分析显示,cyt b序列中A+T含量略高于G+C含量,共检测到54个变异位点,60个样本得到37个单倍型,平均单倍型多样性为0.945±0.018,核苷酸多样性为0.00419±0.00043,遗传多样性表现中等.太湖种群与滆湖种群间的遗传距离最远为0.00651,鄱阳湖种群和巢湖种群之间遗传距离最近为0.00375.分子方差分析(AMOVA)表明,群体间遗传分化系数F_st为0.0684,几乎所有变异都来自群体内,群体间遗传分化极小.cyt b序列构建UPGMA系统进化树显示,5个种群没有分化成不同的分枝谱系,种群间存在广泛的基因交流.;The mtDNA cyt b gene of yellow catfish from five lakes in the middle and lower reaches of the Yangtze River was amplified and sequenced.Result showed that the average contents of A+T were a little higher than that of G+C in the aligned sequences of 955 bp.54 variable sites were detected and 37 haplotypes were recovered.The haplotype diversity and nucleotide diversity were 0.945±0.018 and 0.00419±0.00043,respectively.The genetic distance between Lake Taihu population and Lake Gehu population displayed the highest,up to 0.00651,while that between Lake Poyang and Lake Chaohu was the lowest to 0.00375.The fixation indices (F_st) of analysis of molecular variance (AMOVA) among populations was 0.0684,illustrating no significant population structure.The phylogenetic tree of cyt b built with MEGA 4.1 showed that five populations were not clustered into clades based on genetic distance.There was extensive general flow between yellow catfish populations from five lakes in the middle and lower reaches of the Yangtze River.