摘要:

AbstractThe standing crop and primary productivity of a small eutrophic, prairie‐parkland lake were measured. In general, both standing crops and primary productivity were large, 29.4 and 73.09 mg chlorophyllam−3and m−2and 78.71 and 196.77 mg C hr−1m−3and m−2respectively. Productivity decreased with increasing depth, therefore, decreasing light intensity. Relations between productivity and chlorophyll a content, productivity and light intensity, phytoplankton productivity efficiency and light intensity, productivity and water temperature were investigated, as was the photosynthetic index. Experiments designed to determine the photosynthetic capacity of the phytoplankton distinguished between actively growing and senescent populations. The latter were present during the winte

ISSN:0020-9309    

DOI:10.1002/iroh.19780630102

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractTidal variability of water mass characteristics has been assessed in the upper 100 metres of the Saguenay, a subarctic fjord in Québec, Canada. Temperature and salinity show a maximum variability in the 5‐15 m layer in which vertical oscillations of a very sharp pycnocline are observed. Phosphates, nitrates and chlorophyllaare highly variable above this pycnocline during a tidal cycle, but dissolved oxygen content is remarkably stable in the whole water column. It is concluded that fluctuations of many variables in the subsurface waters might be large enough to hinder high rates of primary producti

ISSN:0020-9309    

DOI:10.1002/iroh.19780630103

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractA change of the thermal regime results in a variety of reactions of both abiotic and biotic components of the environment. The aim of this paper is to present new data (on Turbellaria, Oligochaeta, Hirudinea, Coleoptera and Hydracarina) on biological responses to the thermal factor discussed in a broad context of literature and, to evaluate their impact on the subsequent ecosystem development. A theoretical interpretation of all phenomena related to this factor is proposed within a widely‐conceived theory of adaptatio

ISSN:0020-9309    

DOI:10.1002/iroh.19780630104

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractAt two stations in a Norwegian land‐locked fjord, one more and one less influenced by freshwater run‐off, studies were made of the primary production, chlorophyllaconcentrations, and the quantity and composition of phytoplankton. Samples were taken for analyses of phosphate, nitrate, and silicate, and temperature and salinity were measured. Two kinds of bio‐assays were performed: combinations of phosphate, nitrate, and silicate were added to I, natural water incubatedin situ, and II, natural water incubated in the laboratory. Lower salinities and higher concentrations of all nutrients were found at the station most influenced by fresh‐water. Although the bio‐assays indicated that nitrogen was the main limiting nutrient, the biological parameters showed no consistent differences between the two stations. The similarity is tentatively explained by the growth of nanoplankton algae, partly depending on nutrients other than those

ISSN:0020-9309    

DOI:10.1002/iroh.19780630105

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

摘要:

AbstractThe population dynamics and production ofAcartia clausii, a planktonic marine copepod, were studied during 1973 and 1974 in a small temperate lagoon. An approach which integrated laboratory andin situexperiments with time‐series sampling of the field population was used to analyze seasonal changes in the parameters of population growth (development, growth, fecundity, and mortality) and to elucidate the processes which affect these changes. The objective of the study was to understand the factors which control the seasonal cycle of abundance.The cycles of abundance were similar in the two years of study and were not affected by differences in the cycles of tidal inflow, temperature, and food availability even though the latter two factors appreciably affected growth, development, and fecundity rates. The abundance cycle is controlled by an annually consistent pattern of copepodid and adult mortality believed to be due to predation by the three‐spined stickleback, the dominant fish species in the lagoon. Cannibalism and periodic tidal stimulation of hatching of accumulated eggs in the sediment help to regulate population abundance within seasonal limits.Production by the lagoon population was 229 kg C for the entire study period; 84—88% of the annual production occurred from April through July. In the area of the lagoon greater than 3‐m deep the mean daily productions during the peak months of each year were 70 and 55 mg C m−2for 1973 and 1974, res

ISSN:0020-9309    

DOI:10.1002/iroh.19780630106

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630107

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630108

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630110

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630111

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19780630113

出版商:Akademie Verlag, Berlin    

年代:1978

数据来源: WILEY