摘要:

AbstractPhytoplankton primary production was measured using the14C method once per month from 1973 through 1976 as part of an intensive ecosystem study of a small eutrophic soft‐water lake, under restoration since 1970. Relationships among phytoplankton production, species composition, chlorophyll a content, bacteria, zooplankton and a variety of abiotic environmental factors have been studied. Productivity normally showed one peak in spring and another in summer, whereas a minimum was reached under the ice cover in February or March. Maximum production rates in the depth profile ranged from 3 to 144 mg C · m−3· d−1, integral production from 6 to 510 mg C · m̄−2· d−1. Species of Cyanophyceae, Dinophyceae, Chlorophyceae and Chrysophyceae dominated alternately and showed significant differences in the level and variation of photosynthetic activity. Maximum activity was observed in summer. A high biomass increase during late winter and spring despite low primary productivity resulted from the immigration of the dominant blue‐green alga,Oscillatoria limosa, from the sediment. Energy efficiency increased not only with depth in the light‐limited parts of the euphotic zone but at all depths during bad weather conditions and during the decrease of ir

ISSN:0020-9309    

DOI:10.1002/iroh.19810660102

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660103

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractSeasonal variations in the efficiency of utilization of radiant energy by phytoplankton photosynthesis in a tropical embayment followed the same pattern as that of primary production. showing that incident radiation did not limit phytoplankton production. Peak values in primary production and photosynthetic efficiency coincided with periods of nutrient enrichment caused either by upwelling during the southwest monsoon or by run‐off during the northeast, monsoon. A world‐wide comparison of published data on photosynthetic efficiencies in different latitudes showed that higher efficiency is achieved in the tropics, where the values are similar to those observed on phytoplankton cultures. Based on the maximum efficiency of photosynthesis attained, three regimes can be recognized in tropical waters: 1) regions of upwelling with a maximum of 6%,. 2) coastal bays with 0.7%, 3) oceanic regions with 0.

ISSN:0020-9309    

DOI:10.1002/iroh.19810660104

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660105

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractLago Tupé, a Central Amazonian dystrophic black water “Ria lake” (blocked valley lake), lateral to the Rio Negro, was studied at all depths for a year. Physical and chemical results of that study are presented here as a prelude to the microbiological studies. The lake's origin and morphology are discussed. Results concerned with thermal properties, suspended matter and dissolved solids are presented, in addition to results on ionic composition, alkalinity, hardness, pH and dissolved oxygen. Nutrient studies include section of phosphate and nitrogen and conclude with silicate res

ISSN:0020-9309    

DOI:10.1002/iroh.19810660106

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractNatural populations and culture strains ofOscillatoria redekeiisolated from the same lakes exhibit a great variety of phycoerythrine/phycocyanine ratios even under the same growth conditions. Cytophotometric and spectrophotometric determinations of the phycoerythrine and phycocyanine contents of different strains after exposure to blue‐green and orange‐red light, respectively, suggested that chromatic adaptation ofO. redekeitakes place both at cellular and population level. This wide intraspecific diversity is considered at least one reason for competitiveness in highly eutrophic la

ISSN:0020-9309    

DOI:10.1002/iroh.19810660107

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractThe mineralogy and related chemistry of selected lake and stream sediments from the upper Qu'Appelle River basin in southern Saskatchewan, Canada, was examined. The principal crystalline clay minerals present in the colloidal fractions of the sediments are smectite, vermiculite, kaolinite, mica, quartz, and feldspar. The cation‐exchange capacity of the sediments varies from 16.3 to 28.8 meq/100 g, and the pH ranges from slightly acid to mildly alkaline. The hydrous oxides of Al, Fe, Mn, and Si are present in significant quantities in both the colloidal and noncolloidal fractions of the sediments; this is significant because these oxides likely exert the dominant chemical control on the movement of many nutrients and pollutants in aquatic environments. Calcium and Mg carbonates comprise a significant fraction of the sediments. Most of the C in the sediments is in the organic form; the organic C content varies from 1.2 to 6.0%. Because crystalline clay minerals, poorly ordered sesquioxides, and organic matter play a vital role in the retention and cycling of nutrients and pollutants in aquatic environments, a knowledge of the nature and properties of sediments is fundamental to efforts to preserve and improve the quality of natural water system

ISSN:0020-9309    

DOI:10.1002/iroh.19810660108

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660109

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

摘要:

AbstractA total of 55 taxa belonging toTrachelomonas(Euglenophyta) are reported from Bangladesh. Of these, 5 varieties (Tr. allorgeivar.madaripurense, Tr. anguste‐ovatavar.ellipsoidea, Tr. armatavar.rangpurense, Tr. hispidavar.subcoronata, Tr. asymmetricavar.crenulata) and one forma (Tr. anguste‐ovatafa.minor) are described as new to scie

ISSN:0020-9309    

DOI:10.1002/iroh.19810660110

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19810660111

出版商:Akademie Verlag, Berlin    

年代:1981

数据来源: WILEY