摘要:

A description is given of the larval development ofPyura stolonifera.Ova were obtained by stripping the mature adult gonad and were artificially fertilized. Development is similar to that ofP. squamulosaandP. microcosmus.Successful development in specimens collected from False Bay takes place at 15°C to 25°C, but not at 10°C or 30°C. Rate of development increases with temperature.

ISSN:0035-919X    

DOI:10.1080/00359197609519899

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A mathematical model of the population dynamics of the jackass penguin,Spheniscus demersus, is reported. The model is limited to a set of differential equations using fertility, mortality and recruitment rates to describe changes in four main population classes: eggs, unfledged chicks, immature birds and breeding adults. The value of the model lies in its availability for sensitivity studies of its various parameters, and in pointing out the directions which field research must take if many parameters are to be determined accurately.

ISSN:0035-919X    

DOI:10.1080/00359197609519900

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The ecology of reproduction of the irregular lamp urchinEchinolampas crassa, including the cycle of reproduction, sex ratio, and the feeding and burrowing habits, is reported. Gametogenesis takes place during rising sea temperature and spawning during falling temperature. Reproduction is well synchronized within and between sexes and the greatest densities coincide with gametogenesis, the lowest densities with spawning. Discriminatory behaviour maximizes feeding efficiency and concentrates animals on ripple slopes.

ISSN:0035-919X    

DOI:10.1080/00359197609519901

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Fifty-two species of Ostracoda are distinguished in the Palaeogene succession of Soekor borehole Jc-1 on the continental shelf off Natal. Two species and one new genus are described, and the ostracod faunas can be grouped into four well-defined assemblages. Vertical variations in the make-up of the ostracod faunas, together with various parameters measured in the forminifera populations, are used to discriminate changes in the conditions of deposition and rates of sediment accumulation. These can be summarized: lower Palaeocene environments were hyposaline, restricted circulation, with rapid accumulation; upper Palaeocene through Eocene conditions were normal marine, alternating restricted and open water circulation, with rapid accumulation in the Palaeocene, and slower accumulation in the Eocene; Oligocene conditions were normal marine, with open water given way to restricted circulation, shallow water environments in the upper part. Sediment accumulation rates in the Oligocene vary rapidly, major changes in the composition of the ostracod populations are recognized as important local biostratigraphical events.

ISSN:0035-919X    

DOI:10.1080/00359197609519902

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A method is described whereby earlier work by Kogan and Griem on ion dynamical corrections to the Holtsmark theory of spectral line shapes may be generalized to include the effects of Debye shielding and ion-ion correlations. Expressions for the dynamical corrections to the Holtsmark profile of a single Stark component are obtained to second order in the inverse Debye length. The correction terms are evaluated in the case of a high-density plasma (Ne∼ 1017cm−3), and the results used to discuss the central structure of the hydrogen Balmer β line profile. On the basis of our model, it is concluded that allowance for ion motion, with or without shielding, cannot account for outstanding discrepancies between the calculated and measured central structure of this line, under these conditions.

ISSN:0035-919X    

DOI:10.1080/00359197609519903

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

An active concentrate which promotes behavioural responses in males has been extracted from sea water in which femaleIosus lalandiiwere in ecdysis.

ISSN:0035-919X    

DOI:10.1080/00359197609519904

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359197609519898

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor