吉林省东部粳稻生长和产量对移栽期和温度变化的反应

以中晚熟水稻品种"吉粳811"为研究对象,于2013年和2014年在延吉市进行分期播种/移栽试验,分析了吉林省东部地区一季粳稻生长速度和产量对移栽期及温度变化的响应规律,确定该品种在研究地区的适宜播种期和移栽期,以减免低温冷害的影响。结果表明:播期/移栽期的推迟提升了生长季平均气温,水稻生长发育进程加快,有效生育期缩短,主要生长季内平均气温每升高1℃,水稻生长速率提升19%,生育期缩短5 d左右;吉林省东部地区水稻的适宜移栽温度为日均气温13.0℃,移栽过早或偏晚均导致减产;中晚熟品种水稻在4月18日前后播种、5月26日前后移栽可保证在霜前成熟,且产量高;中晚熟品种水稻移栽至成熟适宜活动积温为2280℃·d左右,活动积温每减少100℃·d,水稻产量下降1095 kg·hm~(-2)(约减产13%);积温不足导致水稻冷害发生,因而减产。     

珠江口南沙河涌浮游植物群落结构时空变化及其与环境因子的关系

随着城市生态健康理念的提出,城市河涌生态健康也受到了前所未有的关注。为更好的了解河涌的水环境和浮游植物现状,于2015年3月至2016年2月对珠江口南沙河涌8个站位水环境和浮游植物群落结构进行调查。结果显示:共发现浮游植物164种(属),隶属7门73属,其中以绿藻种类最多,达33属79种,占48.17%;硅藻次之,17属41种,占25%。优势种为梅尼小环藻(Cyclotella meneghiniana)、假鱼腥藻属(Pseudanabaena sp.)和小球藻(Chlorella vulgaris)。浮游植物细胞密度在0.19×10~6—101.34×10~6个/L内变动,呈现单峰型,在4月发生拟菱形弓形藻(Schroederia nitzschioides)水华,14涌密度高达87.38×10~6个/L,随后因强降雨细胞密度骤降。浮游植物群落的季节演替基本符合PEG(Plankton Ecology Group)模型,从冬季的硅藻,到春夏季的绿藻,再到秋季的蓝藻。One-way ANOVA分析显示,各月份浮游植物细胞密度差异显著(P0.01)。Pearson相关性分析表明绿藻细胞丰度变化主导着浮游植物总丰度的变化(r=0.454,P0.01)。运用Margalef物种丰富度指数、Shannon物种多样性指数、Pielou均匀度指数对水体进行评价表明,调查水体呈中度污染。相关加权营养状态指数表明,河涌全年处于富营养化状态。浮游植物聚类分析表明,时间异质性较高,总体相似性较低;空间上相似性较高,人为活动可能是导致空间差异的关键因子。冗余分析显示,叶绿素a、溶解氧、盐度、水温、总氮和p H与浮游植物群落结构关系最为密切。p H对硅藻门浮游植物影响较大,碱性条件适宜直链藻生长,春季水华形成的驱动因子是盐度、温度和总氮。     

长江中游鱼类寄生棘头虫区系的研究

经过3年10次调查,剖检湖北省宜都、黄冈两处江段所产72种鱼类,共计766尾。收集棘头虫10种,其中包括2新种和1新组合,即蛇鮈新棘吻虫(新种)Neoechinorhynchus saurogobi sp.nov.,长江丽棘虫(新种)Brentisentis yangtzensis sp.nov.(Illiosontidae),鲤丽棘虫(新组合)B.cyprini comb.nov.。对长江中游鱼类寄生棘头虫区系的特点进行了分析和探讨。     

Estimating multiple years,tributary-specific,and overall Atlantic salmon smolt abundance in a large Canadian catchment using capture–mark–recapture experiments

Population monitoring of Atlantic salmon (Salmo salar L.) abundance is an essential element to understand annual stock variability and inform fisheries management processes. Smolts are the life stage marking the transition from the freshwater to the marine phase of anadromous Atlantic salmon. Estimating smolt abundance allows for subsequent inferences on freshwater and marine survival rates. Annual abundances of out-migrating Atlantic salmon smolts were estimated using Bayesian models and an 18-year capture–mark–recapture time series from two to five trapping locations within the Restigouche River (Canada) catchment. Some of the trapping locations were at the outlet of large upstream tributaries, and these sampled a portion of the total out-migrating population of smolts for the watershed, whereas others were located just above the head of tide of the Restigouche River and sampled the entire run of salmon smolts. Due to logistic and environmental conditions, not all trapping locations were operational each year. Additionally, recapture rates were relatively low (<5%), and the absolute number of recaptures was relatively few (most often a few dozen), leading to incoherent and highly uncertain estimates of tributary-specific and whole catchment abundance estimates when the data were modeled independently among trapping locations and years. Several models of increasing complexity were tested using simulated data, and the best-performing model in terms of bias and precision incorporated a hierarchical structure among years on the catchability parameters and included an explicit spatial structure to account for the annual variations in the number of sampled locations within the watershed. When the best model was applied to the Restigouche River catchment dataset, the annual smolt abundance estimates varied from 250,000 to 1 million smolts, and the subbasin estimates of abundance were consistent with the spatial structure of the monitoring programme. Ultimately, increasing the probabilities of capture and the absolute number of recaptures at the different traps will be required to improve the precision and reduce the bias of the estimates of smolt abundance for the entire basin and within subbasins of the watershed. The model and approach provide a significant improvement in the models used to date based on independent estimates of abundance by trapping location and year. Total abundance and relative production in discrete spawning, nesting, or rearing areas provide critical information to appropriately understand and manage the threats to species that can occur at subpopulation spatial scales.     

GROWTH STIMULATION OF ALEXANDRIUM TAMARENSE (DINOPHYCEAE) BY HUMIC SUBSTANCES FROM THE MANICOUAGAN RIVER (EASTERN CANADA)1

In the St. Lawrence Estuary, annual recurrent blooms of the toxic dinoflagellate Alexandrium tamarense L. Balech are associated with brackish waters. Riverine inputs are suspected to favor bloom development by increasing water column stability and/or by providing growth stimulants such as humic substances (HS). A 17‐day culture experiment was conducted to evaluate the importance of HS as growth factors for A. tamarense. Nonaxenic cultures were exposed to four HS extracts from three different sources: humic and fulvic acids isolated from the Manicouagan River, Quebec, Canada; humic acids from the Suwannee River, Georgia, United States; and a desalted alkaline soil extract. For each extract, four concentrations were tested as supplements to the artificial Keller medium, a nitrate‐rich algal culture medium. Additions of HS from all sources significantly enhanced the overall growth rates relative to the controls. Concentrations of HS, estimated by UV spectrophotometry, remained constant throughout the exponential growth phase, suggesting that the HS were acting mainly as growth promoters during our experiment. Dose–response curves indicated that HS could increase the growth rate of A. tamarense even at low concentrations, such as those encountered in the St. Lawrence Estuary. Our results support the hypothesis that HS from the Manicouagan River plume can stimulate the development of toxic dinoflagellate blooms.     

浑河流域2010-2014年的鱼类群落和水生态健康变化分析

为了解浑河流域鱼类群落结构的变化趋势和水生态健康变化,分别于2010年和2014年对浑河流域46个采样点进行了鱼类和环境因子调查。其中2010年采集到鱼类15039尾,隶属于6目9科32种;2014年采集到鱼类10483尾,隶属于6目10科41种。Mann-Whitney U检验表明从2010年到2014年鱼类总物种数、香农多样性指数、底层物种数百分比、植食性和肉食性个体数百分比等鱼类特征参数显著上升。典型对应分析（CCA）结果表明,2010年显著影响鱼类群落结构的环境因子为流速、电导率、河流等级和钙离子浓度;而2014年显著影响鱼类群落结构的环境因子则为电导率、河流等级和氨氮浓度。2010年和2014年的鱼类完整性指数（FIBI）评分分别为48.7624.82和50.4117.35,与2010年的评价结果相比,2014年F-IBI结果稍有改善,其中极好和好的点位数分别少3个和1个,一般的点位数多9个,而极差和差的点位分别少4个和1个。     

黄河鲤性别决定时间和相关基因表达研究

鱼类性别决定和分化机制极为复杂,通过性腺组织切片鉴定得出黄河鲤从未分化性腺发育为Ⅱ期精巢、卵巢的时间为受精后第40天到第80天。选取一些可能参与黄河鲤性别决定分化相关的基因（amh、ar、cyp19a、cyp19b、dax1、dmrt1、er、foxl2、nobox、sox9a、sox9b、zp2）进行实时荧光定量PCR分析各个基因在受精后40d、45d、50d、55d、65d和80d的表达情况。结果显示性别决定相关基因在50d都有高表达,推测45-50 d为性别决定的关键时间。ar、amh、dax1、dmrt1、sox9a、sox9b六个基因在80d雄性表达量升高,且雄性明显高于雌性,推测这些基因参与精巢分化发育过程。cyp19a、cyp19b、foxl2、nobox、zp2五个基因在80d雌性表达升高,且高于雄性,推测其可能参与卵巢分化发育。     

Effects of groundwater salinity on the characteristics of leaf photosynthesis and stem sap flow in Tamarix chinensis

AimsThe objective of this study was to investigate the change pattern of leaves photosynthesis and stem sap flow of Tamarix chinensisin under different groundwater salinity, which can be served as a theoretical basis and technical reference for cultivation and management of T. chinensis in shallow groundwater table around Yellow River Delta.MethodsThree-year-old T. chinensis, one of the dominated species in Yellow River Delta, was selected. Plants were treated by four different salinity concentrations of groundwater—fresh water (0 g∙L^-1), brackish water (3.0 g∙L^-1), saline water (8.0 g∙L^-1), and salt water (20.0 g∙L^-1) under 1.2 m groundwater level. Light response of photosynthesis and the diurnal courses of leaf transpiration rate, stem sap flux velocity and environment factors under different groundwater salinity were determined via LI-6400XT portable photosynthesis system and a Dynamax packaged stem sap flow gauge based on stem-heat balance method, respectively.Important findings The result showed that groundwater salinity had a significant impact on photosynthesis efficiency and water consumption capacity of T. chinensis by influencing the soil salt. The net photosynthetic rate (P_n), maximum P_n, transpiration rate, stomatal conductance, apparent quantum yield and dark respiration rate increased first and then decreased with increasing groundwater salinity, while the water use efficiency (WUE) continuously decreased. The mean P_n under fresh water, brackish water and salt water decreased by 44.1%, 15.1% and 62.6%, respectively, compared with that under saline water (25.90 µmol∙m^-2∙s^-1). The mean WUE under brackish water, saline water and salt water decreased by 25.0%, 29.2% and 41.7%, respectively, compared with that under fresh water (2.40 µmol∙mmol^-1). With the increase of groundwater salinity from brackish water to salt water, light saturation point of T. chinensisdecreased while the light compensation point increased, which lead to the decrease of light ecological amplitude and light use efficiency. Fresh water and brackish water treatment helped T. chinensis to use low or high level light, which could significantly improve the utilization rate of light energy. The decrease in P_n of T. chinensis was mainly due to non-stomatal limitation under treatment from saline water to fresh water, while the decrease in P_n of T. chinensis was due to stomatal limitation from saline water to salt water. With increasing groundwater salinity, stem sap flux velocity of T. chinensis increased firstly and then decreased, reached the maximum value under saline water. The mean stem sap flux velocity under fresh water, brackish water and salt water decreased by 61.8%, 13.1% and 41.9%, respectively, compared with that under saline water (16.96 g·h^-1). Tamarix chinensis had higher photosynthetic productivity under saline water treatment, and could attained high WUE under severe water deprivation by transpiration, which was suitable for the growth of T. chinensis.     

Simulating the rice yield change in the middle and lower reaches of the Yangtze River under SRES B2 scenario

As one of the most important crops in China, rice accounts for 18% of the country’s total cultivated area. Increasing atmospheric CO₂ concentration and associated climate change may greatly affect the rice productivity. Therefore, understanding the impacts of climate change on rice production is of great significance. This paper aims to examine the potential impacts of future climate change on the rice yield in the middle and lower reaches of the Yangtze River, which is one of the most important food production regions in China. Climate data generated by the regional climate Model PRECIS for the baseline (1961–1990) and future (2021–2050) period under IPCC SRES B2 scenario were employed as the input of the rice crop model ORYZA2000. Four experimental schemes were carried out to evaluate the effects of future climate warming, CO₂ fertilization and water managements (i.e., irrigation and rain-fed) on rice production. The results indicated that the average rice growth duration would be shortened by 4 days and the average rice yield would be declined by more than 14% as mean temperature raised by 1.5 °C during the rice growing season in 2021–2050 period under B2 scenario. This negative effect of climate warming was more obvious on the middle and late rice than early rice, since both of them experience higher mean temperature and more extreme high temperature events in the growth period from July to September. The significance effect of the enhanced CO₂ fertilization to rice yield was found under elevated CO₂ concentrations in 2021–2050 period under B2 scenario, which would increase rice yield by more than 10%, but it was still not enough to offset the negative effect of increasing temperature. As an important limiting factor to rice yield, precipitation contributed less to the variation of rice yield than either increased temperature or CO₂ fertilization, while the spatial distribution of rice yield depended on the temporal and spatial patterns of precipitation and temperature. Compared to the rain-fed rice, the irrigated rice generally had higher rice yield over the study area, since the irrigated rice was less affected by climate change. Irrigation could increase the rice yield by more than 50% over the region north of the Yangtze River, with less contribution to the south, since irrigation can relieve the water stress for rice growing in the north region of the study area. The results above indicated that future climate change would significantly affect the rice production in the middle and lower reaches of the Yangtze River. Therefore, the adverse effect of future climate change on rice production will be reduced by taking adaptation measures to avoid disadvantages. However, there is uncertainty in the rice production response prediction due to the rice acclimation to climate change and bias in the simulation of rice yield with uncertainty of parameters accompanied with the uncertainty of future climate change scenario.