洪湖日本沼虾的种群繁殖生物学

１９９４年５月至１９９５年６月对洪湖日本沼虾的种群繁殖生物学进行了研究。洪湖日本沼虾的繁殖期为４月中旬至１０月上旬,５月中旬至８月中旬为日本沼虾的繁殖高峰期,其中６月、８月雌虾抱卵率均在７０％以上;日本 虾群体中雄性总是少于雌性,月性比（♀／♂）变化于１．１０４－５．７８０之间,３－６月性比逐渐增高,７－１０月性比则逐渐降低;在整个繁殖期,４－７月的抱卵是均为前一年出生的大、中规格的个体,之后当年     

洪湖日本沼虾种群生长的研究

１９９４年５月至１９９５年６月对洪河日本沼虾种群的生长进行了研究。日本沼虾群体的平均体长,平均体重在３－６月逐渐增大,之后逐渐降低,分别在８月,９日达到最小值,其后又逐渐增大反映出世代交替的过程。日本沼虾群体的生长存在明显的阶段性,第一阶段的生长可以用Ｌｏｇｉｓｔｉｃ生长模式来描述：（♂）Ｌｔ＝６．８５（１＋ｅ＾０．３１８６－０．２３８６ｔ）,Ｗｔ＝７．５０／（１＋ｅ＾２．３８４５－０．３２５０ｔ     

西江广东鲂(Megalobrama terminalis)繁殖生物学及繁殖策略

探究鱼类繁殖策略是了解鱼类种群动态的关键.通过对珠江西江流域重要的经济鱼类广东鲂(Megalobrama terminalis)生殖周期、产卵时间、成熟期长度、生殖力类型和生殖力等方面进行研究,阐明在人类活动日益加强下,西江广东鲂的繁殖策略适应性变化情况.研究表明,广东鲂个体平均体长245 mm,优势体长集中在260~280 mm,平均体重347 g,优势体重集中在320~480 g.用L 50逻辑斯谛回归方法推算广东鲂雌鱼和雄鱼初次性成熟体长分别为244.5和232.2 mm.雌雄性比例为1.105∶1,且随着体长增加,雌雄性比呈现出先下降后上升的变化趋势.广东鲂繁殖群体在产卵季节为48月,产卵高峰为6月初持续到7月上旬,产卵季节内广东鲂鱼苗的密度与径流量显著相关.广东鲂绝对繁殖力平均为73069粒,相对繁殖力平均为118.7粒/g,绝对繁殖力与体长和体重均呈正相关.广东鲂繁殖群体性腺成熟系数与性腺重、肥满度以及体重密切相关.广东鲂种群繁殖策略在人类活动加剧影响下呈现出适应性变化:初次性成熟体长变小,绝对繁殖力下降.     

大水面日本沼虾(Macrobrachium nipponensis)资源人工增殖

挑选受精卵颜色呈褐色或接近褐色的抱卵虾,放入网箱多点布局孵化,直接放流孵出幼体是大水面日本沼虾资源增殖的有效方法.2001年,采用此法对湖北省阳新县网湖日水沼虾进行增殖,其产量从增殖前(2000年)的10000kg上升至35000kg,取得显著增殖效果,进箱孵化的抱卵数量(N,kg)可用计划生产量(Y,kg),总回捕率(R)及个体平均体重(W,g/ind)计算:N≥Y·(1000·R·W)-1.     

青虾生长规律与群体组成的研究

报道了上海川沙县孙桥河道青虾的生长呈明显的阶段性,如雄虾的第一阶段（1990年6—11月）的生长方程为L_t=3.38[1-e~(-0.4943(t+0.1674)];第二阶段（1991年2—6月）的生长方程为L_t=6.57/(1+e~(2.1805-0.2787t);它们的拐点分别为2.07月龄和11.97月龄。渔获群体分析结果表明,月龄为0-15月,体长范围为1.30—6.58cm,体重范围为0.060—13.39g;一年出现两个群体,其中夏季群体生活期从当年7月至翌年10月,数量大,占群体数量80％以上;秋季群体生活期从当年9月至翌年12月,约占群体数量20％左右。群体中一般雄虾数量多于雌虾数量,月性比(?)在0.61—1.35之间变动。     

湖北武湖日本沼虾的生长特性

从1998年9月至1999年9月对人工养殖湖泊——武湖日本沼虾生长特性作了研究. 以月龄来研究日本沼虾的生长,研究结果表明日本沼虾在7-1月份(1-7月龄)呈等速生长,在2-6月份(8-12月龄)呈异速生长.日本沼虾体重(W)与体长(L)呈幂函数相关,但在7-1月份时其b值接近于3,而在2-6月份时其b值明显小于3,其关系式如下: 1-7月龄:W♂=0. 0148L3. 2419(r=0. 9978,n=390),W♀=0. 0206L3. 0117(r=0. 9968,n=372); 8-12月龄:W♂=0. 0857L2. 1788(r=0.9854,n=188),W♀=0. 1450L1. 8165(r=0. 9974,n=278). 1-7月龄雄虾的生长规律符合Von Bertalanffy方程,雌虾的生长规律符合Logistic方程;8-12月龄雌雄虾的生长规律都符合Logistic方程.     

水丰水库亚洲公鱼和大银鱼种群生态的比较研究

1998年 10月至 2 0 0 0年 11月对水丰水库亚洲公鱼和大银鱼的食性、生长、繁殖、群体结构进行了比较研究 .亚洲公鱼为杂食性鱼类但主要以浮游动物为食 ,繁殖时还摄食同类卵 ,出现频率达 4 2 .9% ,在冬季也摄食大银鱼卵 (2 .8% ) ;体长 (L)、体重 (W)呈异速生长 (W =1.176×10 - 6 L3.5555) ;群体繁殖速度比 1984年以前提高了 4 9.2 % ;群体结构中体长、体重的离散度很小 .大银鱼前期主要以浮游动物为食 ,后期以小鱼小虾为主要食物 ,也捕食公鱼 ,出现频率 6 .9% -9 6 % ;体长、体重呈等速生长 ,W =4 .4 82× 10 - 6 L3.0 0 0 9;群体繁殖速度高出公鱼 1.18倍 ;群体结构中体长、体重的离散度较大 ,表现出了个体间的差异性     

汉江流域黑竹冲河圆顶华溪蟹(Sinopotamon teritisum)的周年生产量及其营养基础

大型底栖动物群落在河流生态系统中发挥着重要作用,2003年6月至2004年6月间对汉江流域2级河流——黑竹冲河大型底栖动物优势种类的生活史和生产力进行为期一周年的研究．结果表明：主要优势种圆顶华溪蟹（Sinopotamon teritisum Dai et al．）生活史周期基本为四年,每年8—10月为主要繁殖季节,衰老个体（体宽〉29mm）在每年的1—2月份死亡较多;现存量在一周年中变化较大,密度9月份达到峰值,为35ind／m^2,生物量在6月达到峰值,为41．7g／m^2;采用体长频率分布法（size—frequency method）测算的周年生产量为151,3071g／（m^2．a）,P／B系数为1．4．在其胃内含物中,无形态碎屑占45．4％,虾占10．9％、水生昆虫占35．6％、螺占5．7％、植物组织占8．1％,对次级生产量的贡献率分别10.84％、18．21％、59．49％、9．52％和1．94％．     

池塘放养中华绒螯蟹长江种群与辽河种群性早熟出现差异的观察与分析

在上海水产大学上海崇明试验基地池塘养殖中发现 ,中华绒螯蟹辽河种群性早熟个体最初捕捉日期为 8月 15日 ,而长江种群为 8月 2 0日 ,二者相差 5d .此后性早熟个体的捕捉数量逐渐上升 ,10月份达高峰期 ,11月份显著下降 .在性早熟蟹群体中 ,辽河种群的性腺发育略领先于长江种群 ,而体重显著低于长江种群 (P <0 .0 1) ;雌、雄性早熟蟹不存在显著的体重差异 ,但雌性个体数量明显多于雄性个体数量 .     

内蒙古乌梁素海叶绿素a浓度时空分布及其与氮、磷浓度关系

采用2005-2007年乌梁素海监测数据,对乌梁素海水体中叶绿素a浓度的时空分布进行分析,并对叶绿素a浓度与总氮、总磷浓度相关关系进行研究,结果表明:乌梁素海叶绿素a浓度具有明显的时空分布特征,在时间上,5月份>7、8月份>10月份>9月份>6月份,可以看出5月份、10月份叶绿素a浓度偏高,其原因是乌梁素海特殊的地域性,补水来源主要为河套灌区的农田退水,5月份、10月份正处于春浇秋灌时期,农田退水携带充足的氮磷元素进入乌梁素海,使藻类迅速增长繁殖;在空间上,北部区>南部区.通过分析得出,2006年叶绿素a与氮、磷浓度的相关关系在5月、10月存在明显的相关性,8月份相关性较小,其他月份无明显相关性.     

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.