Showing papers in "Transactions of The Royal Society of South Africa in 1979"
TL;DR: The St Lucia system is a South African estuarine lagoon which experiences wide salinity fluctuations; recent records show a range of 2%0 to 89%0; the death of these food organisms during periods of extreme salinity may reduce the carrying capacity of the system for crabs.
Abstract: Summary The St Lucia system is a South African estuarine lagoon which experiences wide salinity fluctuations; recent records show a range of 2%0 to 89%0. The population of the crab Scylla serrata in the St Lucia estuary system was surveyed in January 1977. An estimate based upon catch per unit effort indicated a population of about 180 000 adult crabs. Population density declined with increasing distance from the mouth of the estuary. S. serrata was more abundant in muddy than in sandy areas. The crabs survived a four-month period of low salinity (2%0) in 1976, but their hypersalinity tolerance (60%0) is too low to permit their existing in most of the system during periods of high salinity. S. serrata feeds chiefly on benthic molluscs and crustacea; the death of these food organisms during periods of extreme salinity may reduce the carrying capacity of the system for crabs.
36 citations
TL;DR: Ecklonia maxima plants were classified into three growth stages: Type A (small, with a primary blade but no secondaries), Type B (larger, with secondaries on an elongated primary blade) and Type C (very large stipe, shortened primary blade, and large number of secondaries (the sporophylls).
Abstract: Summary Ecklonia maxima plants were classified into three growth stages: Type A (small, with a primary blade but no secondaries), Type B (larger, with secondaries on an elongated primary blade) and Type C (very large stipe, shortened primary blade, and large number of secondaries (the sporophylls), (some bearing tertiaries)). Growth of primary and secondary blades was studied by punching holes 10 cm apart, beginning 10 cm from the base. Primary blades appeared to have a meristem at the base of the blade only; secondary blades had a zone of growth extending at least half-way along the length of the blade. New secondaries were continually budded off at the base of the primary blade, and eroding secondaries were cast off at the tip of the primary. Growth production in Type C plants was concentrated chiefly in a few secondary blades near the middle of the primary. It was concluded that during July and August 1975 primaries, secondaries and stipes were each growing at about 1% per day. Productivity of the Eckl...
31 citations
TL;DR: Methods for the determination of age from otoliths of the kob and the spotted grunter are described and growth curves provide estimates of length for age, while use of length/weight relationships enable estimates of weight for age to be made.
Abstract: Summary Methods are described for the determination of age from otoliths of the kob (Argyrosomus hololepidotus) and the spotted grunter (Pomadasys commersonni.) Growth curves provide estimates of length for age, while use of length/weight relationships enable estimates of weight for age to be made. These are discussed in relation to the age composition of estuarine populations, age at sexual maturity and years of greatest weight increment.
29 citations
22 citations
TL;DR: Water samples taken down the length of Langebaan lagoon reveal a decline in bacterial numbers from Saldanha Bay to the head of the lagoon, with a parallel decline in suspended particles, comparable to zooplankton biomass.
Abstract: Summary Water samples taken down the length of Langebaan lagoon reveal a decline in bacterial numbers from Saldanha Bay to the head of the lagoon, with a parallel decline in suspended particles. Bacterial biomass (x 43, 27 mg.m−3) was comparable to zooplankton biomass. Intertidal samples from different sediment types showed an increase of bacteria towards the southern tip of the lagoon, with decrease in particle size and increases in percentage mud and percentage organic material. Bacteria comprise only a small percentage of the organic pool, but their biomass ranges from 16 to 232 mg (dry weight) per kg of wet sediment. This approximates a mean of 14,2 g (dry weight) per m2 (range 1,32 to 25,74): comparable to the biomass of benthic macrofauna. Considerable seasonal variation occurs in the organic pool.
19 citations
TL;DR: The presence of embryos in the mantle cavity of Tetraclita serrata Darwin, and in Octomeris angulosa Sowerby and Balanus maxillaris Gronovius for comparison, has been monitored and breeding seasons showed slight variation annually.
Abstract: Summary The presence of embryos in the mantle cavity of Tetraclita serrata Darwin, and in Octomeris angulosa Sowerby and Balanus maxillaris Gronovius for comparison, has been monitored. In all species breeding extended over five to eight months, depending on the species. Breeding seasons showed slight variation annually. T. serrata nauplii were cultured on a diet of mussel eggs in the laboratory and the anatomical features of the different nauplius stages are described.
12 citations
TL;DR: In this paper, the authors make corrections and additions to the MUSCI in SIM'S BRYOPHYTA of SOUTH AFRICA, correcting the errors made by the authors.
Abstract: (1979). CORRECTIONS AND ADDITIONS TO THE MUSCI IN SIM'S BRYOPHYTA OF SOUTH AFRICA. Transactions of the Royal Society of South Africa: Vol. 44, No. 1, pp. 113-122.
3 citations
TL;DR: In this paper, the NATURE OF SCIENCE is described as "the natural nature of science" and "the nature of knowledge" in terms of the relationship between science and technology.
Abstract: (1979). THE NATURE OF SCIENCE. Transactions of the Royal Society of South Africa: Vol. 44, No. 1, pp. 1-14.
2 citations
TL;DR: Tongues of 51 Cape chacma baboons (Papio ursinus) were studied macroscopically and histologically to establish the normal structure and possible variations and no condition resembling human plicated tongue, double fissures, central papillary atrophy, lingual thyroid or geographic tongue was found.
Abstract: Summary Tongues of 51 Cape chacma baboons (Papio ursinus) were studied macroscopically and histologically to establish the normal structure and possible variations. The tongue was invariably spatulate in dorsal profile and ovoid in cross-section, and the portion anterior to the circumvallate papillae constituted 80% of its total length. Only minor variations were seen, such as accessory circumvallate papillae, differences in the number of lateral grooves in the foliate papillae, and the presence or absence of a central longitudinal dorsal fissure. No link was found between the place of origin or the sex of the animal and these variations. No condition resembling human plicated tongue, double fissures, central papillary atrophy (median rhomboid glossitis), lingual thyroid or geographic tongue was found.
1 citations
TL;DR: Writing a computer program to perform computer-aided design makes demands of skill and judgement far greater than are required to produce the same design without the aid of a computer.
Abstract: Summary Writing a computer program to perform computer-aided design makes demands of skill and judgement far greater than are required to produce the same design without the aid of a computer. However, serious problems can arise if one accepts the results of such programs unquestioningly, and without subjecting them to the critical analysis a manually produced design would receive. These points are discussed in relation to a computer program written to design large steel storage tanks of a type widely used in the chemical and petroleum industries.