ISSN:0035-919X    

DOI:10.1080/00359198309520091

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The Eerste River is situated in the south-western Cape Province, South Africa. Its upper reaches have a stony substratum, and can be divided into three physical/biotic zones: the Mountain Stream, Upper River and Lower River zones. Investigations of the abundance, biomass, species diversity and species composition of the benthic macro-invertebrates in the three zones were carried out in 1975/76. Spatial and temporal changes in these factors can be correlated with changes in the physico-chemical quality of the water. Abundance and biomass generally increased downstream, but were low below a dam construction site, because of the blanketing effects of silt on the substratum. Seasonal changes in abundance and biomass differed in the three zones, but always included a peak in spring. The highest values of both were in the Lower River in summer, reflecting the build-up of organic pollutants there during times of low flow. Diversity of the Ephemeroptera, which was felt to be representative of a change in diversity of the fauna as a whole, generally decreased downstream, with a major drop at the town of Stellenbosch, and another at a sewage-farm outfall. A misleading increase in diversity occurred, however, in the silt-laden waters below the dam site, due to the fleeting occurrence of individuals of several different species. Composition of the fauna was typical of local rivers with mountain sources.

ISSN:0035-919X    

DOI:10.1080/00359198309520092

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Analysis of sea-surface temperature patterns along the South African coastline indicates that between 31 °S and 33 °S latitude there is an unusually rapid decline in temperature. This region also defines the southern limit of the distribution ofMacrobrachium petersi.Compared with the larvae, post larvalM. petersiare less tolerant of high salinity in combination with low temperature. These results may explain the restricted southern African distribution ofM. petersi.

ISSN:0035-919X    

DOI:10.1080/00359198309520093

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Changes in the thermal and salinity structure were recorded in the Keiskamma estuary during a dry (1979–80) and a wet (1980–81) summer respectively. In the dry summer the estuary was homogeneous with respect to salinity and temperature, whereas in the wet summer it was markedly heterogeneous. These highly variable conditions are discussed in relation to those found in American, European and Australian coastal plain estuaries.

ISSN:0035-919X    

DOI:10.1080/00359198309520094

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A frigate was deliberately sunk in August 1978 in False Bay, in 32 metres of water, with a view to creating an artificial reef. Fish attracted to the reef were counted monthly until September 1979. After four months there was an appreciable fish community dominated by reef-associated Sparidae, mainlyPachymetopon blochiiandSarpa salpa. Non-reef-associated filter feeders used the reef as shelter from time to time. The majority of the reef-associated species were transient and capable of moving from reef to reef; there were very few permanent residents. The community was compared with that of a nearby artificial reef created in 1972. The possible effects of the reef profile on the community are discussed. It is concluded that the establishment of a few artificial reefs of a similarly small size is unlikely to improve fish catches in False Bay.

ISSN:0035-919X    

DOI:10.1080/00359198309520095

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Samples of South African kelp seaweeds collected over a period of 21 months were analysed for algin content (as a percentage of anhydrous mass) by a colorimetric method. This method was an adaptation of a procedure described by Blumenkrantz & Asboe-Hansen (1973), who used the colour reaction betweenmeta-hydroxydiphenyl and furfurol to measure concentrations of purified uronic acids and of uronic acids in urine. While the algin content may fluctuate as much as 50% within a year, there was little evidence to suggest any marked seasonal variation in the content of eitherMacrocystisorLaminariaor in stipe samples ofEcklonia. Results did suggest some seasonality in the algin content ofEckloniablades, with winter values up to 50% higher than summer values. However, this is much less than the seasonal fluctuations reported in blades of certain European kelps. The algin content ofLaminaria, and to a lesser extent ofEcklonia, was inversely related to size and class, and was found to vary within different regions of the plant. In general, blades ofEckloniaandLaminariacontained more algin than stipes, but there was little difference between stipe and blade samples ofMacrocystis.

ISSN:0035-919X    

DOI:10.1080/00359198309520096

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The results of experiments to determine the temperature relationships of the active rate of oxygen uptake in the whelkBullia digitalisare reported. These are compared with previously published data on the temperature relationships of ‘inactive’ and controlled activity routine rates. At all levels of activity the rate of oxygen consumption of intact animals is markedly temperature independent over the range 10 to 20 °C. This contrasts with results gained on the oxygen uptake of whole body tissue homogenates, the latter being temperature dependent. Possible explanations for this difference are discussed and proposals made for further research on the control of metabolism in this species.

ISSN:0035-919X    

DOI:10.1080/00359198309520097

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198309520098

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198309520099

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198309520100

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor