浅水湖泊四种渔具捕捞选择性及对鱼类群落影响比较研究

了解不同种类和大小的鱼类对各种捕捞方式的脆弱性, 对于制定最佳的捕捞策略和合理开发鱼类资源至关重要。研究从渔获物组成、捕捞效率和个体大小等方面, 对长江中游典型湖泊牛山湖的四种渔具(网簖、刺网、电捕和鸬鹚)的捕捞选择性进行了比较分析。使用相对重要性指数(IRI)评价渔具捕捞对鱼类物种的选择性, 同时通过计算渔获物的平均营养水平(MTL)和饵料鱼与凶猛性鱼类的重量比, 分析捕捞对鱼类群落营养结构的潜在影响。结果表明, 网簖和电捕捕获的鱼类种数多、体长范围广, 对鱼类资源的破坏性最大, 应当加以限制或废除; 鸬鹚是捕获鳜(尤其是高龄鳜)的一种有效方式, 但对幼鳜和其他幼鱼也有较大损害, 应控制其捕捞强度; 刺网主要捕获几种经济鱼类, 并可平衡捕食者和饵料鱼之间数量关系, 是利用鱼类资源的一种较好方式, 关键在于对刺网网目大小和捕捞强度的限制。建议湖泊捕捞应从单一物种转向多物种综合管理, 并考虑物种之间的营养生态关系, 以更好地保护和可持续利用渔业资源。     

洱海微囊藻水华的水生态风险评估研究

以洱海微囊藻水华为研究对象, 借鉴生态毒理学风险评估思路对藻类水华的水生态风险进行评价。研究通过暴露实验以及查阅文献获取了微囊藻水华对底栖动物、浮游动物、鱼类和沉水植物的效应数据, 采用毒性百分数排序法推导了洱海微囊藻水华的急性和慢性效应藻密度, 用风险商值评估微囊藻水华密度的水生态风险。进一步结合水华盖度和持续时间制定了微囊藻水华的急性、慢性生态风险评价表。研究结果表明, 微囊藻水华的急性生态风险分为低中高三级, 分别为微囊藻藻密度小于3.4×106 cells/L为低风险,微囊藻藻密度在3.4×106—3.4×107 cells/L之间为中风险,微囊藻密度大于3.4×107 cells/L为高风险。慢性生态风险同样分为低中高三级, 分别为微囊藻藻密度小于1.1×106 cells/L为低风险,微囊藻藻密度在1.1×106—1.1×107 cells/L为中风险,微囊藻密度大于1.1×107 cells/L为高风险。实际应用中需综合微囊藻水华密度、面积和持续时间, 制定洱海微囊藻水华水生态风险评价标准。当微囊藻水华处于中风险状态时, 应启动预警、强化水质管理和生物抑制措施, 当处于高风险状态时, 应采取水华的应急处理措施。研究结果有助于洱海微囊藻水华的科学管理。     

MICROBIAL COLONIZATION ON NATURAL AND ARTIFICIAL MACROPHYTES IN A PHOSPHORUS-LIMITED,HARDWATER LAKE1

Epiphyte communities in a phosphorus-limited hard-water lake were compared over a 14-week period from Potamogeton illinoensis and structurally similar artificial plants of different leaf ages. Artificial plants were serially incubated in the lake to simulate the age of natural leaves. The physiognomy of loosely attached epiphytes appeared similar on the two substrata. Algal cell number and biovolume were 15-fold and 17-fold higher, respectively, on artificial leaves early in the growing season, but total algal density gradually became similar on natural and artificial plants. In contrast, the taxonomic composition of loosely attached algae became increasingly distinct, and mean cell biovolume on natural leaves was twice that on artificial leaves. Adnate epiphytes on both substrata developed from sparse populations of bacteria on new leaves to a community of diatoms, blue-green algae and numerous bacteria on mature and senescent leaves. Adnate community succession on natural leaves in late senescence/death differed from that on artificial leaves colonized for comparable periods in having (1) a marked increase in filamentous blue-green algae, (2) a subsequent decrease in all algae, and (3) a final fungi-dominated stage. The trends in colonization indicate that macrophytes in this oligotrophic lake provided a distinct habitat from that of artificial substrata for epiphytes throughout the growing season.     

EFFECTS OF PRE-WEANING AND POST-WEANING UNDERNUTRITION ON ACETYLCHOLINE LEVELS IN RAT BRAIN

Abstract— Studies were made of the effects of undernutrition during the neonatal period and also protein deficiency and undernutrition during the post-weaning period on brain acetylcholine. Rats undernourished from birth to 4 weeks so as to result in a body wt deficit of 43 per cent had an associated deficit in brain wt of 14 per cent, but the concentration of acetylcholine in the brain was not affected. In the case of post-weaning undernutrition, acetylcholine concn was found to be affected in protein deficiency as well as in severe calorie restriction.     

强力霉素在斑点叉尾(鲴)体内药物动力学及残留消除规律研究

研究利用高效液相色谱法研究了强力霉素在斑点叉尾 (Ictalurus punctatus)体内的药物动力学与消除规律, 有助于制定合理用药方案和休药期, 为水产品质量安全提供理论依据。(1)单次口服剂量 20 mg/kg 强力霉素在斑点叉尾 体内的药时数据符合二室开放式模型。药-时曲线呈明显双峰现象: 第一次达峰时, 强力霉素在肾、血和肌肉中浓度迅速上升, 达峰时间 Tmax (1)出现在 30min, 强力霉素在肝脏中浓度上升缓慢, 出现在 1h; 肝、肾、血和肌肉第二次达峰的时间 Tmax (2)出现在 8h, 第二次达峰浓度 Cmax(2)大于第一次的浓度Cmax (1)。 药-时曲线下面积(AUC): 肾、肝、血和肌肉分别为 63.242、1282.077、142.379、62.348 μg·h /mL。消除半衰期[T1/2b]: 肾、肝、血和肌肉分别为 40.668、48.767、36.527、31.091h, 平均滞留时间(MRT): 肾、肝、血和肌肉分别为 46.585、56.989、48.859、42.428h; (2)连续口服剂量 20 mg/kg 的强力霉素 5d, 停药后强力霉素在斑点叉尾 肝脏中浓度最高, 肌肉+皮中浓度最低。在不同组织中强力霉素的消除速率不同(P<0.05), 药物消除速度由高到低依次为肌肉+皮、肾脏、肝脏。若以肝脏为靶组织, 最高残留限量 300 μg/kg,休药期不低于 30d; 若以可食组织肌肉+皮为靶组织, 最高残留限量 300 μg/kg, 休药期不低于 19d。     

亚热带湖泊中一种剑水蚤──Mesocyclops notius Kiefer的形态及生态学研究(英文)

本文报道了对一亚热带湖泊中的Mesocyclopsnotius的形态及生态学研究。将从扁担塘采得的标本形态学特征与Kiefer和Velde从澳大利亚的标本的形态学特征进行了比较．在扁担塘,M.notius与2种温剑水蚤──ThermocyclopstaihokuensisHarada和T.brevifurcatusHarada为春季和夏季剑水蚤的优势种,而CyclopsvincinusvincinusVljanin为冬季的优势种。     

EFFECTS OF FASTING AND FEEDING ON SERUM UREA AND SERUM CREATININE LEVELS IN POLAR BEARS

Polar bears were held in captivity and fasted for an average of 38 d prior to being fed for three days. Blood samples were collected prior to feeding and then at one and three days post-feeding in 1984 and at one, four, and seven days post-feeding in 1985. The ratio of serum urea to serum creatinine varied significantly in 1984, rising from a pre-feeding mean of 11.0 (SE = 2.6) to 32.0 (SE = 3.2) on the first day post-feeding and then dropped to 22.8 (SE =3.2) in the last sample. In 1985, the ratio of serum urea to serum creatinine increased from a pre-feeding mean of 15.8 (SE = 2.3) to 61.2 (SE = 10.6) after three days of feeding and dropped to a mean of 29.2 (SE = 5.1) seven days after feeding ended. Serum urea levels varied over the study period in both years. No significant variation in serum creatinine levels was found in 1984, but in 1985, serum creatinine levels demonstrated significant variation, declining from the pre-feeding mean of 1.83 mg/dl (SE = 0.29) to 0.96 mg/dl (SE = 0.12) in the last sample.
The findings suggest that polar bears can have a low serum urea to serum creatinine ratio, similar to that found in hibernating black bears, or higher ratios after feeding. Polar bears can rapidly return to a fasting serum urea to creatinine ratio after food is withheld. Polar bears may demonstrate urea conservation, similar to that found in black bears, and may be able to move between a fasting and a feeding metabolism based on food availability throughout the year, an adaptation to life on the labile sea ice.     

FISHING TECHNIQUES AND FOODS OF THE PIED KINGFISHER ON LAKE VICTORIA IN UGANDA

Douthwaite, R. 3. 1976. Fishing techniques and foods of the Pied Kingfisher on Lake Victoria in Uganda. Ostrich 47: 153–160.

Pied Kingfishers fish by diving from hovering flight or from perches; the choice is influenced by location of the prey and the weather, especially wind speed. 40–50% of the dives into Lake Victoria were successful compared with 11% on the Kazinga Channel, near Lake Edward, but dives were made more frequently in the latter area.

Analysis of pellets from the northern shore of Lake Victoria showed the bulk of the adults' diet was composed of Haplochromis, 55–108 mm (median 80 mm) total length, but that Engraulicypris urgenteus. 40–64 mm (median 52 mm) total length was more important numerically. Flying termites, Macrotermes sp., were occasionally eaten in large numbers.

Size selection related to development determines the proportions of Huplochromis and Engraulicypris in the chick's diet. by comparison with the adult most bone consumed by the chick is digested. Two caged juveniles ate about 34.5 g of fresh fish daily, 45% of their post-absorptive weights. Wild birds may consume even more.     

武汉东湖湖球蚬种群动态及生产力的研究

1999年 6月至 2 0 0 0年 5月对武汉东湖湖球蚬进行了周年研究。湖球蚬年均密度和生物量分别为 10 0 2ind /m2 和12 1g/m2 ,密度和生物量的高峰分别出现在 4月 (2 97ind /m2 )和 3月 (4 3 8g/m2 ) ;湖球蚬为一年一代 ,其种群含有 3个年龄组 ,其中 1999年龄组占绝对优势。利用瞬时增长率法和体长频率法计算湖球蚬的周年生产量为带壳湿重4 2 79g/m2 ,去壳干重 2 4 4g/m2 ,P/B系数为 3 5 5。同时湖球蚬的生产力动态也被研究 ,结果表明其生产量累积过程主要发生在春季和秋季。     

淤泥湖近太湖新银鱼的生物学及其增殖途径的研究

近太湖新银鱼的生殖期为春夏季的３月底至６月上旬,产卵盛期为４月上旬和５月上旬。性成熟年龄为１年,属分批产卵类型。终生以浮游动物为食。生长１年平均全长为６８．７ｍｍ,平均体重为０．７０ｇ。产卵后不久死亡,寿命只有１年。捕捞近太湖新银鱼的合理时期为冬季,捕捞期内划定禁渔区和向禁渔区放流部分亲本。产卵盛期人工放流受精卵或银鱼苗。     

急性重复缺氧对小鼠脑组织腺苷及其A1受体的影响

分别应用酶鉴别分光光度法和放射性配体结合法测定小鼠脑组织腺苷（ａｄｅｎｏｓｉｎｅ,ＡＤＯ）含量及Ａ１受体在急性重复缺氧过程中的变化。发现经急性重复缺氧处理的动物全脑内ＡＤＯ含量有一定程度的累积增加,尤其在海马、脑桥和延髓处的增加较为显著;各脑区Ａ１受体的数目显著低于正常对照组,但海马、脑桥和延髓处Ａ１受体的亲和力显著高于正常对照组。结果提示,重复缺氧后虽然脑内Ａ１受体数目减少,但由于海马、脑桥和延髓处Ａ１受体的亲和力升高,累积增加的ＡＤＯ和Ａ１受体结合后,抑制神经细胞兴奋性的作用仍可能得到加强,从而使ＡＤＯ仍能更好地发挥抑制性神经调制作用。     

底栖硅藻应用于河流生态系统健康评价的研究进展

硅藻是水生态系统中最重要的初级生产者之一, 不仅为生态系统中其他消费者提供碳源, 也因分布广泛、种类多、世代时间短等特点, 通常被认为是水环境及生态系统良好的指示生物。文章介绍了河流生态系统健康及生物完整性的概念, 综述了硅藻尤其是底栖硅藻在水生态系统中的自身特点及作用; 概述了硅藻在生物监测中广泛应用的前提: 对环境因子的响应和国内外对硅藻及硅藻指数在河流生态监测中的研究进展; 介绍了广泛应用的硅藻指数及基于硅藻的生物完整性指数的原理及构建方法; 指出了硅藻及硅藻指数在生物监测及评价中可能所存在的问题, 并提出了今后我国在这个领域后期需开展的工作。     

富营养化湖泊规模化种养的水葫芦与浮游藻类的相互影响

水葫芦(学名凤眼莲,Eichhornia crassipes Solms)是被公认为去除富营养化水体氮、磷效果较好的水生漂浮植物[1—3],也是目前生态修复工程中应用较广的水生漂浮植物[4]。随着《太湖流域控制性种养水葫芦技术规范》的出台,水葫芦安全控养模式在太湖流域的应用相对较为成熟。目前,研究者们对于水葫芦应用的顾虑由最初的影响     

巢湖蓝藻腐殖化过程中形态与成份变化研究

通过对巢湖蓝藻进行微生物腐殖化改造,模拟藻类早期成岩过程,对蓝藻样品进行光学显微镜和扫描电镜形态观察,并对蓝藻样品有机元素、族组分和同位素数据及热重/差热进行分析。研究表明:蓝藻经微生物改造后,由群体生存逐渐转变为以个体形式存在,体内生化成分逐渐被降解。蓝藻样品有机N、S元素经微生物降解后,含量不断减少,蓝藻氯仿沥青A含量最高可达11.98%。进入厌氧阶段后,饱和烃和芳烃组分大量生成,沥青质含量明显增加,非烃部分减少。芳烃碳同位素富集12C,其它族组分逐渐富集13C。蓝藻气态烃排放量最大量为4.0%,游离态烃排放量随处理过程的深入逐渐增大,最高可达47.7%,烃排放的总吸热量逐渐减少,最低为14.77mW·s/mg。微生物对蓝藻改造过程效果显著,可为藻类烃源岩研究提供现代对比实例。