太湖贡湖湾虾类种类组成与时空分布特征

分别于2005年4月、7月、10月利用蹦网对贡湖湾虾类种类组成和时空分布进行调查.共采集到虾类9605尾,属于2科3属5种,分别是秀丽白虾(Exopalaemon modestus)、日本沼虾(Macrobrachium nipponense)、锯齿新米虾中华亚种(Neocaridina denticulata sin...     

浙江铜山源水库美国大口胭脂鱼的年龄组成及生长

2002-2004年,在浙江衢州铜山源水库,对该库放养的美国大口胭脂鱼的生长情况进行了研究,结果表明,该水 库美国大口胭脂鱼的鳞片以环片的切割型为主要年轮特征．用刺网所捕的美国大口胭脂鱼渔获物中以Ⅱ、Ⅲ、Ⅳ龄个体为 主．体长和体重的关系式为：W=8．595×10~(-5)15 L~(2.662),Von Bertalanffy 生长方程的主要生物学参数：L_∞=36．54cm,W_∞= 1．245kg,K=0．6377,t_0=-0．261龄,体重生长的拐点年龄 t_1=1．92龄,拐点体重W_1=0．396kg．与池养鱼类生长情况相 比,铜山源水库的美国大口胭脂鱼生长较慢．     

太湖鱼类产量、组成的变动规律及与环境的关系

湖泊生态系统健康包含两个方面的内涵:满足人类社会合理要求的能力和湖泊生态系统自我维持与更新的能力.获知湖泊生态系统健康状况及其区域分异特征,对于湖泊管理具有重要意义.本文基于对太湖的野外调查,计算了表征湖泊生态系统健康的系统能、系统能结构、生态缓冲容量和湖泊营养状态指数.聚类分析结果表明,太湖不同湖区生态系统健康状况存在一定差异,东部湖区较好,西部湖区较差,呈现由东南部湖区向西北部湖区递减的趋势.该结果对进一步研究湖泊生态系统健康评价指标阈值具有重要的参考意义.     

桥梁群体震害预测方法的研究

本文研究了桥梁群体震害预测方法的理论，并采用模糊数学、灰色系统理论和概率分析方法，建立了中、小型桥梁群体震害预测的数学模型，在对江南一带城市地震震害预测工作中桥梁抽样单体震害预测经验法的计算基础上，给出了公路桥梁在不同地震烈度影响耻的单因素评价矩阵，为区域性的地震震害预测工作提供了一个有力的实用工具。     

中太平洋Allison海山富Co结壳Os同位素组成及其生长间断与生长年代的确定

以中太平洋Allison海山的富钴结壳Al—1为研究对象,在其结构观察的基础上,平均按1．3mm间隔取样,测定各分层Os同位素组成,建立了^187Os／^188Os随深度演化曲线．通过与40Ma以来的大洋海水的Os同位素组成演化曲线对比,并结合^10Be年龄模式下的Os同位素曲线的变化特征,识别出了两次生长间断（H1和H2）．H1和H2分别发生于13．6～29．6和6．8～9．8Ma．在此基础上,确定了结壳A1—1生长年龄标定方案：对于小于6．8Ma的壳层,其年龄用旧Be年龄模式标定;对于大于6．8Ma的壳层,其年龄用Os同位素曲线标定．如此确定的该结壳最内层形成年龄（最老年龄）为39．5Ma．     

地球内部物质组成及其性质的研究

地球内部物质组成的研究涉及对地表现象的深入解释,与地球动力学、地球热结构及宇宙演化有着密切的关系.本文综述了这方面的研究结果及近期的进展,指出两种地幔模型的主要分歧点,讨论了地幔中的主要相变及与间断面的关系,对今后研究提出四点意见.     

凤鲚繁殖群体的生物学特性及因数关系的研究

本文对繁殖季节的209尾凤鲚标本进行了生物学分析。在采获的标本中,最大体长182mm,体重23.4g;最小体长94mm,体重3.5g。肥满度（k）平均为3.15×10^-4。其体长与体重的回归关系式为W=1.174×10^-5L^2.773。雌鱼的绝对繁殖力平均为7403.48粒,成熟系数为18.92%。雄鱼成熟系数8.02%。绝对繁殖力与体长呈曲线回归关系,F=1.906×10^-2L^2.54,与体重呈直线回归关系,F=688.13W—2119.68。     

温度对铜绿微囊藻群体培养体系中细菌群落组成及稳定性的影响

微囊藻藻际细菌影响微囊藻的生长及其水华的生消.然而特定微囊藻群体中藻际细菌群落组成对温度变化的响应规律仍不清楚.本文把一株从太湖分离得到的群体铜绿微囊藻,置于不同温度（15、20、25和30℃）下进行培养,分析各培养体系中不同粒径附生或游离细菌群落组成的异同.结果表明：温度显著影响微囊藻群体（>20 μm）附生、单细胞小群体（3~20 μm）附生和游离（0.2~3 μm）细菌群落的组成（PERMANOVA,P<0.01）,Sphingomonadales、Pseudomonadales和Cytophagales分别是3组细菌群落中的最优势菌目,相对丰度分别为21.35%、19.74%和33.44%.在3组细菌群落中都存在一些核心优势细菌类群,其丰度相对稳定,对温度变化不敏感.其中在微囊藻群体附生细菌群落中,优势菌属Brevundimonas和OPB56在20~30℃之间培养时其相对丰度较为稳定;单细胞小群体附生细菌群落中的核心优势菌属Mariniradius相对丰度也是在20~30℃之间较为稳定,而Gemmobacter相对丰度在4种温度下均较为一致;游离细菌群落中的核心优势菌属Porphyrobacter相对丰度在20~30℃之间时也相对稳定.另外,在15℃时,单细胞小群体附生和游离细菌群落的多样性都达到最高,总体细菌群落物种相关性网络复杂度最高,但合作性关联最弱.该研究结果对于深入了解微囊藻群体的藻菌关系有重要意义.     

吉林省地震活动规律的研究和趋势预测

本文采用传统的分析方法，总结了吉要省地震活动的时空分布规律，在地震空间分布的可公度性，中等地震序列的前兆意义和区域地震活动对我省的影响程度等问题研究的基础上，提出吉林省地震的时空演化趋势。     

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     

北京两个水库的桃花水母及其发生条件初探

为鉴定北京怀柔水库和黄松峪水库发生的桃花水母并检验其水环境质量相关性,对2022年9月9日和10日采自2个水库的桃花水母进行形态学和遗传结构分析,并结合常规水生态监测数据,初步探究桃花水母发生的水环境条件。结果显示,怀柔水库和黄松峪水库桃花水母形态结构较为相似,依据其伞径、触手数目、主辐触手长于其它触手、管状平衡囊数、刺丝囊疣圆锥状环状排列及囊状性腺等形态特征初步鉴定为索氏桃花水母和嘉定桃花水母。ITS序列分析结果显示怀柔水库样本与索氏桃花水母遗传相似性100%,黄松峪水库样本与嘉定桃花水母遗传相似性100%,佐证了形态学鉴定结果。2个水库桃花水母发生前后库区pH、溶解氧、总氮和总磷浓度以及生化需氧量等因子无明显差异,而水温和食源浮游动物生物量变动明显,水质处于中营养-轻度富营养状态。9月上旬,2个水库水温快速下降到25℃以下,而适口食源浮游动物生物量增长至1.2 mg/L以上。推断:1)桃花水母环境耐受力较强,偏爱食物丰富的中营养水体;2)水温骤变(骤升或骤降)和适口食物充裕可能是刺激桃花水母启动有性生殖的重要生态因子。据此分析了温变胁迫和营养限制对桃花水母发生的可能驱动效应,以期为...     

Modelling the effects of temperature and food on individual growth and reproduction of Daphnia and their consequences on the population level

Individual based simulations of population dynamics require the availability of growth models with adequate complexity. For this purpose a simple-to-use model (non-linear multiple regression approach) is presented describing somatic growth and reproduction of Daphnia as a function of time, temperature and food quantity. The model showed a good agreement with published observations of somatic growth (r² = 0.954, n = 88) and egg production (r² = 0.898, n = 35). Temperature is the main determinant of initial somatic growth and food concentration is the main determinant of maximal body length and clutch size. An individual based simulation was used to demonstrate the simultaneous effects of food and temperature on the population level. Evidently, both temperature and food supply affected the population growth rate but at food concentrations above approximately 0.4 mg Cl⁻¹ Scenedesmus acutus temperature appeared as the main determinant of population growth.

Four simulation examples are given to show the wide applicability of the model: (1) analysis of the correlation between population birth rate and somatic growth rate, (2) contribution of egg development time and delayed somatic growth to temperature-effects on population growth, (3) comparison of population birth rate in simulations with constant vs. decreasing size at maturity with declining food concentrations and (4) costs of diel vertical migration. Due to its plausible behaviour over a broad range of temperature (2–20 °C) and food conditions (0.1–4 mg Cl⁻¹) the model can be used as a module for more detailed simulations of Daphnia population dynamics under realistic environmental conditions.     

Influence of stock origin and environmental conditions on the survival and growth of juvenile freshwater pearl mussels (Margaritifera margaritifera) in a cross-exposure experiment

The freshwater pearl mussel (Margaritifera margaritifera) is a highly specialized and sensitive freshwater bivalve, whose survival in the juvenile phase is indicative of high quality habitats. This contribution investigates the use of juvenile freshwater pearl mussels as bioindicators, considering the influence of mussel stock and study stream conditions on juvenile performance, as described by survival and growth rates. A standardized cross experiment was carried out investigating juvenile performance in four different pearl mussel stocks originating from the Rhine, Danube and Elbe drainages, representing distinct genetic conservation units. The juveniles were exposed in five study streams which were selected to integrate pearl mussel streams with different water qualities and recruitment status of the mussel population. Per study stream, five standard mesh cages containing an equal number of 20 (10 × 2) juvenile pearl mussels per stock in separate chambers were installed. Survival and growth rates of juveniles were checked after three months (i.e. before their first winter) and after nine months (i.e. after their first winter). Mussel stock and study stream conditions significantly influenced juvenile performance. Growth rates were determined by study stream conditions and increased with stream water temperature, organic carbon and C/N ratios. Survival rates varied stock-specifically, indicating different levels of local adaptation to their native streams. Due to the detection of stream-specific differences in juvenile performance, freshwater pearl mussels appear suitable as bioindicators. However, a careful consideration of stock-specificity is necessary to avoid false interpretation of bioindication results. The comparison of stock-specific survival in native versus non-native streams implicates that exposure of juveniles outside their native habitats is able to increase breeding success or else serve for risk spreading in breeding programs.     

Reproductive traits of the freshwater shrimp Caridina fossarum Heller, 1862 (Decapoda, Caridea, Atyidae) in the Ghomp-Atashkedeh spring (Iran)

In the present study, some biological traits of Caridina fossarum reproduction are studied in the Ghomp-Atashkedeh spring (Fasa, Shiraz, Iran), for the first time. This Iranian endemic freshwater species was studied from April 2007 to March 2008. Minimum sexable size (MSS) and absolute or relative size at the onset of maturity (SOM and RSOM) in terms of carapace length (CL) was found to be 2.4 mm, 4.3 mm and 55%, respectively. Sex ratio showed variations on a monthly basis. Sex reversal is a possible scenario for C. fossarum because the size-specific sex ratio revealed a reverse pattern. Based on the proportions of ovigerous females, the main breeding season was determined to be from April to August, demonstrating a peak during early spring. There is a period of extended recruitment at water temperatures above 20 °C. The size at which 50% of females are mature was estimated at CL = 5.03 mm from the proportion of ovigerous females during the breeding season. The pleopodal egg number varied from 3 to 75 eggs per female with a mean value 34.39 ± 14.27. The results showed that although there is a significant relationship between carapace length CL and pleopodal egg number, it is not the most important factor affecting potential fecundity in C. fossarum due to the low values of slope (= 1.51) and determination coefficient (= 0.052).     

Effect of mixed toxic diets (Microcystis and Chlorella) on the rotifers Brachionus calyciflorus and Brachionus havanaensis cultured alone and together

Brachionus havanaensis is a common planktonic rotifer sometimes found together with Brachionus calyciflorus in Microcystis-infected waterbodies in México. Here, we evaluate the impact of mixed diets (dry weight basis, 0%, 25%, 50%, 75% and 100% Microcystis or Chlorella) on the growth of and competition between B. calyciflorus and B. havanaensis. In general, a higher proportion of Microcystis aeruginosa in the diet resulted in decreased population growth rate of both rotifer species. Whether grown separately or together, B. havanaensis was always numerically more abundant than B. calyciflorus, regardless of the proportion of Microcystis in the diet. However, when both species were grown together, the impact of M. aeruginosa in the diet had a more adverse effect on B. calyciflorus than on B. havanaensis. When grown alone, both rotifer species showed better population growth on a diet of 75% Chlorella and 25% Microcystis than either 100% Chlorella or Microcystis.     

Human waterborne protozoan parasites in freshwater bivalves (Anodonta anatina and Unio tumidus) as potential indicators of fecal pollution in urban reservoir

The presence of environmentally robust dispersive stages of intestinal protozoan parasites in waters represents an important public health threat since these pathogens have caused numerous outbreaks related to either drinking or recreational waters. The purpose of this study was to evaluate the presence of Cryptosporidium oocysts, Giardia and Blastocystis cysts, and microsporidian spores in mussels collected from municipal reservoir, Lake Malta (Poland, Europe). Two species of freshwater bivalves (Anodonta anatina and Unio tumidus) were tested for the enteropathogens. A direct wet smear and smears stained with chromotrope 2R, Ziehl–Neelsen and iron hematoxylin made from each pellet of the hemolymph, gills and gastrointestinal homogenates of mussels were examined microscopically. In the study the immunofluorescence antibody test kit MERIFLUOR Cryptosporidium/Giardia was also used for all bivalve samples. None of investigated parasites were found in U. tumidus. In A. anatina, Cryptosporidium oocysts and Blastocystis cysts were detected in 15.4 and 5.1% of mussel samples, respectively. The present results indicate contamination of Lake Malta with Cryptosporidium and Blastocystis, which is important from the point of view of public health threats because of different human uses of studied reservoir.     

Regional variations in trace element concentrations in tissues of black tiger shrimp Penaeus monodon (Decapoda: Penaeidae) from South Vietnam

The goal of the present study was to examine the specific bioaccumulation of 22 trace elements in muscle, exoskeleton and hepatopancreas of black tiger shrimp Penaeus monodon from the Mekong River Delta (MRD), and the South Key Economic Zone (SKEZ), South Vietnam. The general tendency in most trace element concentrations among different tissues were hepatopancreas > exoskeleton > muscle. Comparisons of trace element levels in tissues between the two regions showed that concentrations of Se in muscle and As in all three tissues were higher in SKEZ; whereas in MRD, the higher concentrations of most elements such as Mn, Cu, Cd, Ba, Hg, were observed in tissues. These geographical variations in trace element levels may reflect the differences in human activities between the two regions of South Vietnam. The target hazard quotient (THQ) values for trace elements (<1) indicate that local residents are not exposed to potential health risks via the consumption of shrimp.     

Feeding of European cisco (Coregonus albula and C. lucinensis) on the glacial relict crustacean Mysis relicta in Lake Breiter Luzin (Germany)

Lake Breiter Luzin, located in north-eastern Germany, is known for the rare occurrence of sympatric populations of European cisco, Coregonus albula and C. lucinensis. Moreover, the lake is inhabited by the glacial relict crustacean Mysis relicta, currently found in only three other lakes in Germany. In the present study, the role of M. relicta in the diet of ciscoes was investigated. Between 2001 and 2002 ciscoes, mysids and zooplankton were caught in Lake Breiter Luzin and stomach contents of ciscoes were analysed. There were seasonal changes in the food items in the stomachs, largely reflecting changes in prey availability. The main food items were copepods (45–81%) and mysids (5–26%). Cladocerans had high amounts in the diet only in summer. Seasonal changes in selectivity were also noted for most prey groups. There were also some consistent patterns of prey preference, with an overall preference for mysids. In general, the prey composition in cisco stomachs did not show significant diet changes, but there were some significant differences between day and night feeding in single prey groups, such as cladocerans. Diet composition of ciscoes varied with the different depth strata in which the fish were caught. With increasing depth, the proportion of mysids in the diet significantly increased, whereas that of copepods significantly decreased. Between C. albula and C. lucinensis, no distinct differences in feeding were evident. Mysids provided an additional and important food resource to ciscoes, and were mainly consumed when the availability of other prey organisms decreased, as in autumn and in the deeper strata of the water column. However, mysids preyed on the same food organisms as ciscoes, indicating a strong competition for food between fish and mysids.