Abundance and diversity of planktonic rotifers in the Po River

Zooplankton samples from the middle reach of the Po River were collected daily from 27 July to 24 August 1988 from a station located near Viadana. Changes in the biocoenosis structure were analyzed in relation to variations in flow rate. Rotifers accounted for more than 99% of the total zooplankton (protozoans excluded) in every sample. The dominant species were Brachionus calyciflorus, Brachionus bennini, Brachionus budapestinensis and Epiphanes macrourus. Under scanty flow conditions, the taxocoenosis showed marked stability. An increase in flow rate acts as a disturbance factor leading to a significant decrease in both total density and dominance.     

异育淇鲫及其双亲同工酶的比较研究

用4.5％聚丙烯酰胺凝胶平板电泳研究了异育淇鲫及其母本淇鲫和父本兴国红鲤的肌可溶性蛋白以及肾、肝、眼、背白肌和心等五种组织的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)和酯酶(EST)。结果发现:异育淇鲫的肌可溶性蛋白以及同工酶的电泳图谱与母本淇鲫相同而与父本兴国红鲤显著不同,因而认为异育淇鲫是淇鲫雌核发育的产物,父本基因对子代基本无影响。在此基础上,本文对异源精子在雌核发育中所起的生物学作用进行了初步探讨。     

Lampetra (Eudontomyzon) gracilis,a synonym of Eudontomyzon danfordi

Synopsis Evidence is presented which suggests that the nonparasitic lamprey, Lampetra (Eudontomyzon) gracilis Kux, 1965, is conspecific with the parasitic lamprey Eudontomyzon danfordi Regan, 1911. The diagnostic characters of the holotype and of the non-type material of E. gracilis are features found in E. danfordi specimens in their second and final year of adult life, thereby making the former a junior synonym of the latter.     

污水和污水土地处理系统中各种水质对华西蟾蜍蝌蚪红细胞微核率的影响

本文使用蝌蚪红细胞微核率作为指示器研究明通河污水和用污水土地处理系统处理后水质的致突变性。蝌蚪在各种水样品中暴露7天。采心脏血制片。在对照组中,微核率分别为4.40‰和4.68‰。1/4明通河污水组诱发蝌蚪的微核率是17.01‰。同对照组相比有明显的差异。     

青甘边区黑河流域森林植被带及其昆虫区系的组成

黑河发源于青海、甘肃交界的祁连山区,是甘肃河西走廊最大的内陆河水系之一,水源丰富,流量稳定,这不仅取决于祁连山区大气降水和冰川融水,更重要的是与上游森林植被密不可分。但是,由于森林害虫猖獗成灾,严重威胁着这一地域森林的生存。近几年我们在森林昆虫普查的基础上,对黑河流域森林昆虫     

Distribution of F-actin in the compound eye of the blowfly,Calliphora erythrocephala (Diptera,Insecta)

Summary Sexual stimulation of males has been reported to affect hypothalamic oxytocinergic systems. In the present study we used radioimmunoassays of micro-dissected forebrain regions and immunocytochemical analysis of Vibratome sections to study the oxytocin systems of naive males, males killed after one mating, and males mated daily with different receptive females for 3 weeks. In males that had mated once, less oxytocin-immunoreactive neurons were observed in the paraventricular (PVN), supraoptic (SON) and periventricular (NPE) nuclei than in naive males. However, after repeated matings, the number of immunoreactive neurons and their staining intensity was increased in these regions. Furthermore, additional oxytocinergic neurons could be found in the lateral subcommissural nucleus, the zona incerta and the ansa lenticularis of repeatedly mated males. Oxytocin-immunoreactive neurons were only occasionally seen in these areas in unmated males or in animals that had been killed after initial mating. Radio-immunoassays of microdissected PVN, SON, NPE and the lateral hypothalamus confirmed the reduction in oxytocin-immunoreactive levels after a first mating by a male and the increase after repeated matings. It is likely that oxytocin secretion into peripheral and portal circulation is stimulated by the endocrine conditions associated with initial mating. These immediate effects may be followed by the activation of synthesis in oxytocin neurons in several sites of the basal forebrain.     

The species composition,occurrence and temporal stability of submerged aquatic macrophyte patches along the main channel border of pool 5A,Upper Mississippi River

Species composition, relative abundance, distribution and physical habitat associations of submerged aquatic macrophytes in the main channel border (MCB) habitat of Pool 5A, Upper Mississippi River (UMR) were investigated during the summers of 1980 and 1983. The submerged aquatic macrophytes in Pool .5A MCB were a small and stable component of the river ecosystem. Submerged plants occurred primarily in small, monospecific clumps. Clumps in close proximity to each other formed plant patches. Plant patches were stable in location and number between 1980 and 1983; 82.5% of the patches first observed in 1980 were present in 1983. Submerged macrophytes covered about 10–12 ha of the 201 ha MCB in Pool 5A. Submerged plants were most common in the lower two-thirds of the pool. Ten species of aquatic macrophytes occurred on rock channel-training structures and eleven occurred on non-rock substrates in the MCB. The most common submerged plants, in order of abundance, were Vallisneria americana Michx., Heteranthra dubia Jacq., Potamogeton pectinatus L., Ceratophyllum demersum L. and Potamogeton americanus C. & S.     

Plankton und Stoffhaushalt der Mosel bei der Stauhaltung Enkirch 1981

River plancton becomes an important factor in rivers affected by man, as a result of a permanent abundance of P and N, and of a lowering of current velocity transforming a river into a chain of storage basins. This process is demonstrated by means of data from the storage basin of Enkirch on the river Mosel, where in summer the growth of plancton leads to an oxygen deficiency. The mechanisms involved are shown. They are controlled by flow, global radiation, and temperature.

     

Age and growth of a colonizing minnow,Barbus anoplus,in a man-made lake in South Africa

Synopsis Aspects of the life history of Barbus anoplus were studied in Lake le Roux, a turbid man-made lake on the Orange River, South Africa. This minnow underwent a population explosion and successfully colonized the shoreline of the newly-formed lake during the early phases of reservoir filling. Male and female B. anoplus reach sexual maturity in one year at about 40 mm fork length. They have a multiple spawning habit with the first spawning in November–January and the second in February–March. The growth of the two resulting cohorts is discussed. It is proposed that the offspring from the second spawning not only acts as a ‘back-up’ but is capable of prolonging the life of that year-class into an additional reproductive season. Most of the minnows die after their second summer, but more offspring from the second spawning, especially females, live into a third summer. Females attain a larger maximum size (73 mm FL) and age (3–4 years) than males (60 mm FL, 2–3 years). B. anoplus is small and short-lived with a high seasonal reproductive potential, which is in contrast to the larger Barbus species in the Orange River system. These life-history traits enable the species to colonize and successfully inhabit unstable environments and probably account for its widespread distribution.     

图们江流域林区居民点鸟类群落的研究

居民点鸟类与人类关系极为密切,在居民点生态系统中起着不可忽视的作用,因此对其生态学的研究具有一定意义。杜恒勤(1958、1959)、周昌乔等(1959)、钱国桢(1964)、郑光美(1965、1982),赵正阶(1981)等,对麻雀、家燕、金腰燕等居民点鸟类进行过大量种群生态学研究。居民点鸟类群落研究和数量统计,尚未见有报道。