摘要:

AbstractThe oxygen budget of the river Zschopau, a flowing water typical of hilly areas in the south of the GDR, was investigated in regard of seasonal variations in the activity of submerged macrophytes. Oxygen concentrations were continuously measured in the river by means of electrodes. Seasonal activity patterns ofRanunculus penicillatus, the dominant macrophyte in the river stretch investigated, were found by laboratory experiments.The oxygen budget was obtained by measuring CO2concentrations by infrared gas analysis (IRGA) and CO2and O2concentriations by means of electrodes.

ISSN:0020-9309    

DOI:10.1002/iroh.19870720602

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19870720603

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractComparison of the number of species and biomass of planktonic crustaceans with morphometric, hydrological, and hydrochemical features of lakes in the zone of temperate climate shows that there are no functional correlations between the development of zooplankton and each of the other separate factors. Results of multiple regression analysis for description of relationships between biotic and abiotic conditions were unsatisfactory (R2⩽0.7) for the greater part of studies. It is apparently necessary to find methods to examine environmental characteristics limiting biological productivity in lakes and to classify lakes on this basis. Such classification may allow to work out quantitative predictions of plankton and benthos biomass development in response to change of some environmental factor

ISSN:0020-9309    

DOI:10.1002/iroh.19870720604

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractReproduction has been studied ofParamysis lacustris, pontocaspian relict, in the centre of its natural area, and in southern and northern zones of acclimatisation. Life cycles of the animals are identical in the distribution area. The effect of female size on fecundity is only slightly expressed within each generation. Significant correlations of these indices were obtained in seasonal aspect. Specific fecundity is represented by maximum values in the centre of the area and declines in the north‐western direction of introduction. The relation of fecundity to egg weight reflecting correlation ofK‐rreproduction strategy is reduced in the regions of introduction. Reproduction effort, i.e. ratio of eggs weight to female weight, is the most stable index within the distribution area. Cumulative potential growth, including soma as well as generative products, was nearer in spite of considerable temperature difference in animal gro

ISSN:0020-9309    

DOI:10.1002/iroh.19870720605

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractSurvival data, in addition to data on growth and reproduction rate, are necessary to estimate rotifer productivity under various thermal conditions. A method of individual culturing ofPhilodina roseolahelped the authors to obtain data concerning length of life span and realisation of reproduction potential at different temperatures, ranging from 9 to 35 °C. The method also was helpful in revealing the causes of individual deaths. It is shown that at a temperature of 20 °C net reproduction rate (R0) ofPh. roseolais maximum and is equal to reproduction potential of the individual. The peculiarity ofPhilodinaontogenetic reaction to temperature beyond optimum is the impairment of reproduction proces

ISSN:0020-9309    

DOI:10.1002/iroh.19870720606

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19870720607

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractGrowth ofTubifex tubifexon highly caloric activated sludge and poor in organic matter natural silt was experimentally studied. The relationship between oxygen consumption rate, weight, and caloric value ofT. tubifexbody in culture on activated sludge was determined to calculate the growth efficiency (K2=P/P+R). The growth rate has been determined, and models ofT. tubifexgrowth are given under various trophic conditions conforming to results of the experiment. Somatic growth, generative growth and life span of this species were compared on the basis of the experiments and literature. Acceleration of growth and prolongation of life under conditions of caloric food and delay of these processes in silt poor in organic matter have been established and measured.T. tubifexwas found to have advantages as compared to other tubificid species in response to increasing amounts of nutrient food in waters polluted by organic matter and, therefore, to produce abundant populations under these conditions.

ISSN:0020-9309    

DOI:10.1002/iroh.19870720608

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractMaterial from 49 localities in Europe, Asia and Africa is used to study two similarDiaphanosomaspecies,viz. D. mongolianumUENO, 1938, andD. lacustrisKORINEK, 1981, both of which were described earlier under other names, the most common of which were “D. brachyurum”, “D. leuchtenbergianum” and “D. birgei lacustris”. These species are redescribed in detail, consideration being given to interpopulational and individual morphological variability, the type material, and material from type localities. The morphology of the setae of the swimming antennae is studied in detail, and the author concludes that some of them are not only used for swimming but also perform a sensory function. Some aspects of the biology of the species are described. They inhabit water bodies of different types, are often so abundant that they constitute the main component of zooplankton communities, and are an important link in the trophic chain. Little known cases of the co‐occurrence ofDiaphanosomaspecies in a water body are described. Localities known forD. mongolianumandD. lacustrisare situated mainly in the temperate and subtropical zones, the former species penetrating farther north than the latter. However, they are also found in the White Nile (Sudan) and Ethiopian lakes. This southward penetration may be connected with the azonal distribution of fluviatile fauna and with the altitude of Et

ISSN:0020-9309    

DOI:10.1002/iroh.19870720609

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

摘要:

AbstractSeveral experiments were performed to test the toxicity of FIT, a washing‐up and general cleaning liquid containing about 10 % sodiumalkanemonosulfonate (industrial name E 30) to spawn and larvae of anura. The LC50values for spawn were between 1.62 × 10−3% (Rana dalmatina) and 4.97 × 10−3% (Rana temporaria). The sensitivity of anuran larvae depends on the concentration and duration of exposure to the detergent as well as on the developmental and differentiation stage of the organisms. The toxicity of FIT is not due solely to the alkanesulfonate it contains, but results from the joint action of the surfactant, polyphosphates and solvents.The results indicate that detergents may be harmful to the amphibian fauna of Central

ISSN:0020-9309    

DOI:10.1002/iroh.19870720610

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19870720612

出版商:Akademie Verlag, Berlin    

年代:1987

数据来源: WILEY