摘要:

AbstractA large number of conventional and less conventional discharge measuring techniques applicable to lower order streams are discussed. The intention is to provide aquatic biologists and water chemists with sufficient alternative methods so that a suitable choice may be made based on factors such as stream characteristics, required accuracy and available funding and man‐power. In each case the method is described, details of design and use outlined, and areas of application and possible deficiency noted. In addition the criteria determining method selection are discusse

ISSN:0020-9309    

DOI:10.1002/iroh.19780630602

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630604

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractThe factors influencing the density, diversity and species composition of benthic invertebrate communities in 20 lakes in the Canadian arctic and subarctic were determined during 1975, 1976 and 1977. Despite small differences in nutrient and phytoplankton levels among the lakes, there was a strong positive correlation between these parameters and the density and diversity of the communities. Other factors, including maximum summer water temperature, lake depth and surface area had little overall effect on the communities. The densities of 2 ultra‐oligotrophic chironomids (Heterotrissocladius oliveriandMicropsectracf.groenlandica) increased markedly in cold deep lakes. However the abundance of the majority of species, most notablyProcladius denticulatus, Tanytarsussp., andStictochironomussp., was not effected by temperature. Other species, (Pontoporeia affinis, Monodiamesa bathyphilaandDicrotendipes nervosus) were probably restricted in their northern distribution by temperature. Surface area usually had little effect on the densities of all common specie

ISSN:0020-9309    

DOI:10.1002/iroh.19780630605

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630608

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractYear‐round changes of phytoplankton, organic and inorganic seston, and dissolved and suspended concentrations of Ca, Mg, Na, K, Fe, Mn, Zn, and Cu were studied and correlated in Long Lake, an ultra‐oligotrophic alpine flowage lake of northcentral Colorado, U.S.A. Dissolved cation levels for Ca, Mg, Na, K, Mn, and Fe, both sestonic fractions and phytoplankton densities reached and sustained a maximum during April and May under heavy cover of ice and snow, and a minimum during open‐season from mid‐June to mid‐October. Rates of monthly water renewal varied greatly with a low of 0.28 turnovers in April and a high of 15.37 turnovers in June. Massive flushing in June and July reduced dissolved Fe levels to8.0 mg/l in April and May. Tests for linear correlation between the various cations, sestonic fractions and phytoplankton showed in most cases positive and significant (p<.05) relationships. For most dissolved Fe and Mn pairings with phytoplankton and seston exceptionally significant (p<0.001) relationships were

ISSN:0020-9309    

DOI:10.1002/iroh.19780630609

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractThe rate of conversion of chlorophyll‐ato phaeophytin‐ain dilute acid organic solvents is markedly pH‐dependent. The widely used spectrophotometric measurement before and after acidification to discriminate between chlorophyll‐aand phaeopigments is applicable only between pH 2.6—2.8. At higher pH the reaction proceeds slowly and occasionally may be incomplete. At lower pH complicating reactions may occur, such as breakdown of certain carotenoid pigments causing (time‐dependent) increase of background absorption, and formation of di‐cations of phaeophytin with spectral characteristics different from the usually obtained mono‐cations of phaeophytin. Consequently, it is stressed to control carefully the acid concentration, the water content of the solvent, and the amount of MgCO3used in the filtration procedure. In general, for the purpose of spectrophotometric acidification experiments, acidification by dilute hydrochloric acid added to organic solvents containing 10—20% water, and omission of MgCO3would be preferable.On the basis of observed complications in the red part of the absorption spectrum of the pigment extract, it is recommended to use the abov

ISSN:0020-9309    

DOI:10.1002/iroh.19780630610

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractVariations in quantity and structure of phytoplankton in the lower 630 km stretch of the Tigris were studied and discussed. The Chlorophyceae generally contributed more genera to the phytoplankton community, and the Bacillariophyceae and Cyanophyceae ranked second and third, respectively. The phytoplankton generally showed considerable local and seasonal variations at the surfaces of the sampling locations.

ISSN:0020-9309    

DOI:10.1002/iroh.19780630611

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractEnlarged versions of the MACER sled‐mounted suprabenthic sampler were tested, improved, calibrated and used extensively (598 tows) at depths of 10—384 m since 1968 in the Gulf and Estuary of the St. Lawrence. Two half‐metre zooplankton nets are mounted at 28—64 and 106—142 cm from the sea‐bed, on a steel chassis and toboggan plate. Each has a flow‐meter and 3 horizontal shutters which open via a lever upon contact with the sea floor. They close automatically, through springs and water pressure, whenever the sled leaves the bottom, ensuring uncontaminated suprabenthic samples. Although heavy (228 kg), the device is sturdy, used like a beam trawl, reliable, and collects very little sediment. It has been used to study micro‐stratification above bottom. Data on filtered water volumes, special problems encountered and future improvement

ISSN:0020-9309    

DOI:10.1002/iroh.19780630612

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630613

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractLake Amvrakia is judged by the authors to be a semipolje. Chalky formations 1—5 m above present water level indicate that formerly the level was highe

ISSN:0020-9309    

DOI:10.1002/iroh.19780630615

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY