Showing papers in "Transactions of The Royal Society of South Africa in 1977"
TL;DR: A detailed survey of the physical and chemical characteristics of the water in Saldanha Bay and Langebaan Lagoon to establish base-line conditions in the region prior to the development of the bay as a major port and industrial centre was carried out in this paper.
Abstract: Summary In April 1974 the Sea Fisheries Branch commenced a detailed survey of the physical and chemical characteristics of the water in Saldanha Bay and Langebaan Lagoon to establish base-line conditions in the region prior to the development of the bay as a major port and industrial centre. The thermohaline characteristics of the water resemble those of the Benguela Current, although in summer surface heating and evaporation tend to raise the temperature and salinity somewhat. This is most marked in the Langebaan Lagoon where surface temperatures and salinities in excess of 24 °C and 37 %0 were recorded during the latter part of summer. A variety of chemical parameters were determined. These include a number of heavy and transition elements, dissolved oxygen, nitrate/nitrite, inorganic phosphorus, total phosphorus, reactive silica, pH, chlorophylls, chemical oxygen demand and oxygen absorbed. Data for some of these parameters are tabulated, and indicate that the bay is at present relatively unpolluted. P...
43 citations
TL;DR: Saldanha Bay is wave controlled and can be related to the energy levels created by the refraction pattern as mentioned in this paper, and four energy zones are distinguished in the inner bay: a centrally exposed zone, two marginal semi-exposed zones, a sheltered zone in the north and a bay/lagoon transitional zone in south.
Abstract: Summary Sediment distribution in Saldanha Bay is wave controlled and can be related to the energy levels created by the refraction pattern. Four energy zones are distinguished in the inner bay: a centrally exposed zone, two marginal semi-exposed zones, a sheltered zone in the north and a bay/lagoon transitional zone in the south. Sediment is supplied on the abrasion platform of the exposed zone and along the rocky shoreline of the North Channel. These areas display the coarsest sediments. In North Bay medium sands dominate, whereas the South Channel is characterized by very fine sands. Both semi-exposed zones as well as the sheltered zone consist of very fine sand. The bay/lagoon transitional zone is constructed of a tidal delta made of fine sand. Sediment distribution seems to be in equilibrium with the prevailing hydrodynamic regime. In contrast, Langebaan Lagoon is a current controlled regime. Four physiographic units can be separated: tidal channels, subtidal flats and sandbanks, intertidal flats, and...
40 citations
TL;DR: In this paper, a map of 20 terrestrial plant communities found in the vicinity of Langebaan Lagoon is presented, based on the Braun-Blanquet method of vegetation sampling and data synthesis, and on the photo interpretation of 1:10 000 scale colour aerial photographs.
Abstract: Summary An account, with illustrations, is given of 20 terrestrial plant communities found in the vicinity of Langebaan Lagoon. A map is included which is based on the Braun-Blanquet method of vegetation sampling and data synthesis, and on the photo interpretation of 1:10 000 scale colour aerial photographs. Known rare and endangered plants occurring in the Saldanha—Langebaan area are listed. Recommendations are made for the establishment of a nature reserve which includes the marsh communities around the lagoon and the varied West Coast Strandveld vegetation on the Langebaan Peninsula.
40 citations
TL;DR: Spatial and temporal changes in the distribution of food organisms potentially available to curlew sandpipers Calidris ferruginea at Langebaan Lagoon are described, and there was a positive correlation betweenThe distribution of benthos and sediment parameters at the different sites, macrophyte sites having a higher fine fraction and organic content.
Abstract: Summary Spatial and temporal changes in the distribution of food organisms potentially available to curlew sandpipers Calidris ferruginea at Langebaan Lagoon (33 °S, 18 °E) are described for the period February 1974—March 1975. The inter-tidal benthic fauna at sandy sites showed spring and autumn peaks in biomass and numbers. The fauna was dominated by the gastropod Assiminea globulus, which comprised 62,5% of the total biomass. A Production: Biomass ratio of 4,96 was found for this species, and 1,36 for the amphipod Urothoe grimaldi. The fauna at sites containing macrophytes (Spartina, Zostera, Arthrocnemum) showed winter peaks in biomass and numbers. Classification and ordination confirmed the discreteness of macrophyte and non-macrophyte sites, each having its own characteristic benthos. There was a positive correlation between the distribution of benthos and sediment parameters at the different sites, macrophyte sites having a higher fine fraction and organic content.
34 citations
TL;DR: In this paper, the distribution and numbers of waders on the low-tide sandflats and at high tide roosts at Langebaan Lagoon during the austral summer of 1975-6 are described.
Abstract: Summary The distribution and numbers of waders on the low-tide sandflats and at high-tide roosts at Langebaan Lagoon during the austral summer of 1975–6 are described. The sandflats in Rietbaai, and at the lower and upper sections of the lagoon supported the highest densities of waders. Several species were restricted in their distribution. The majority of the high-tide roosts, incorporating some 30 000 waders, were situated on Arthrocnemum saltmarsh, especially between Bottelary and Geelbek. Approximately 1 000 waders (3 % of the lagoon's population) roosted on the beaches along the Atlantic coastline at high tide. Many thousands roosted on the beach north of Langebaan village at night. The wader community consumed an estimated quantity of food equivalent to 20,8 kcal/m2 per year. Between 2,1 and 6,2 kcal/m2 per year are returned as faeces to the lagoon system. Feather material deposited in the lagoon was equivalent to 0,06 kcal/m2 per year.
31 citations
TL;DR: In this article, a diver-operated suction sampler was used to sample 15 stations in Langebaan Lagoon using a rarefaction technique to define relative species richness and by ash-free dry-weight biomass determinations.
Abstract: Summary Fifteen stations were sampled in Langebaan Lagoon using a diver-operated suction sampler. The macrofauna was analysed using numerical methods, by the rarefaction technique, to define relative species richness and by ash-free dry-weight biomass determinations. Three basic groups were defined which were the channel, island and sandbank groups. The channel and island groups had the greatest biomass and the highest species richness values respectively. In contrast the sandbank group had the lowest biomass values, intermediate species richness values and the highest density of individual animals per m2 The availability of food, water current velocity and hence sediment texture, water temperatures and salinity apparently were most important factors in determining the distribution of the macrofauna.
29 citations
TL;DR: In Langebaan Lagoon, between February 1971 and February 1972 monthly measurements of phytoplankton primary production were made at six stations in Langeban Lagoon as discussed by the authors.
Abstract: Summary Between February 1971 and February 1972 monthly measurements of phytoplankton primary production were made at six stations in Langebaan Lagoon. The gross primary production rates obtained showed a marked seasonal variation. They increased from 261,6 mgC/m3/day in winter to 675,4 mgC/m3/day in spring and to a maximum of 885,3 mgC/m3/day in summer. Production rates ranged from 611,0 mgC/m3.day at the entrance of the lagoon to 162,6 mgC/m3/day at the station nearest to the head of the lagoon. A correlation between total chlorophyll and gross primary production was established for the lagoon, and was used in conjunction with chlorophyll concentrations and water transparency measurements from Saldanha Bay to estimate the gross primary production for the bay. The estimates ranged from 864,9 mgC/m2/day to 3 301,2 mgC/m2/day.
24 citations
TL;DR: In this article, the zooplankton of Langebaan Lagoon and Saldanha Bay are described on the basis of 127 plankton samples taken between 1946 and 1976.
Abstract: Summary The zooplankton of Langebaan Lagoon and Saldanha Bay are described on the basis of 127 plankton samples taken between 1946 and 1976. Hydrological conditions are described indicating a range from marine conditions in Saldanha Bay to hypersaline conditions at the head of the Langebaan Lagoon. Different zooplankton communities occur in different parts of the Saldanha-Langebaan system. In Saldanha Bay the plankton is composed predominantly of species which occur in the neritic plankton of the west coast. The plankton of Langebaan Lagoon is distinct but elements of the Saldanha Bay plankton community penetrate the lagoon to various extents. At the head of the lagoon the plankton community is estuarine in character which is remarkable as Langebaan Lagoon is not an estuary. The significance of this is discussed. Zooplankton biomass was highest in the middle reaches of Langebaan Lagoon ([xbar] = 41,80 mg/m3) and lowest at the head of the lagoon ([xbar] = 16,84 mg/m3) where the lowest diversity index also ...
15 citations
TL;DR: A critical review of old records of Algae of Saldanha Bay accompanies accounts of more recent surveys, reaching the conclusion that the algal flora is basically of the South African west coast; modifications are imposed by protection from wave stress.
Abstract: Summary A critical review of old records of Algae of Saldanha Bay accompanies accounts of more recent surveys within this bay. The range of habitats includes rocky and sandy substrata, shores comparable with those of open coasts in terms of surf stress and those in which water movement is so reduced as to be little more than tidal ebb and flow. The conclusion is reached that the algal flora is basically of the South African west coast; modifications are imposed by protection from wave stress.
13 citations
TL;DR: In this article, a geochemical and petrographic examination of onland phosphorites from the southwestern Cape is made to elucidate their origin and to compare them with the known offshore occurrences.
Abstract: Summary A geochemical and petrographic examination of onland phosphorites from the south-western Cape is made to elucidate their origin and to compare them with the known offshore occurrences. The investigation shows that some of the massive phosphorites and phosphatic pebbles on land have probably formed as phoscretes in a similar manner as calcretes, whereas some of the pelletal deposits originated by disaggregation of phosphorite rock, which was derived by interstitial precipitation. This mechanism is in contrast to the mode of formation suggested for the offshore phosphatic deposits where replacement of calcium carbonate by calcium phosphate is the major diagenetic process. A model which takes these two modes of formation into account is discussed briefly.
12 citations
TL;DR: Aspects of the biology of Choromytilus meridionalis were studied while investigating possibilities for cultivating mussels, and the growth rate of mussels suspended from rafts was determined and indicates considerable variation within the study area.
Abstract: Summary Aspects of the biology of Choromytilus meridionalis were studied while investigating possibilities for cultivating mussels. Plankton samples were taken regularly, and growth, development and settlement behaviour of the larvae are discussed and correlated with results of a larval rearing experiment. Methods are described for the recording of settlement, and the results indicate annual, seasonal and local fluctuations in intensity of settlement at a number of sites. Reference is made to results obtained in Liideritz Bay. The growth rate of mussels suspended from rafts was determined and indicates considerable variation within the study area. This is discussed and aspects of the annual growth curves are presented. Water temperatures were obtained in Saldanha Bay during 2,75 years by means of a continuous recorder.
TL;DR: In this article, the average major and trace element data are reported for recent sediments from Saldanha Bay and Langebaan Lagoon, which are composed mainly of SiO2 and CaCO3 (SiO2+CaCO3 > 93 %).
Abstract: Summary Average major and trace element data are reported for recent sediments from Saldanha Bay and Langebaan Lagoon. Chemically, the sediments are composed mainly of SiO2 and CaCO3 (SiO2 + CaCO3 > 93 %). The sediments are considered to be a three-component mix of quartz, calcite and a granitic fraction presumed to be derived from local granitic rocks.
TL;DR: The Varswater Formation at Langebaanweg is the most prolific source of Pliocene fossils in Africa and significant fossil occurrences of Middle Pleistocene to Holocene age are also recorded as mentioned in this paper.
Abstract: Summary Late Cenozoic deposits in the Saldanha region contain abundant palaeontological and archaeo logical materials. The vertebrate fossil record dates back about five million years, with the Varswater Formation at Langebaanweg being the most prolific source of Pliocene fossils in Africa. Significant fossil occurrences of Middle Pleistocene to Holocene age are also recorded. Human occupation of the region apparently began in the Middle Pleistocene, although most of the local archaeological sites are much younger and date from the latter part of the Holocene.
TL;DR: In this article, a detailed continuous seismic reflection profiling and side-scan sonar surveys were made of the part of Saldanha Bay that lies to the landward of a line connecting Hoedjiespunt and Salamanderpunt (the ‘inner’ bay).
Abstract: Summary Detailed continuous seismic reflection profiling and side-scan sonar surveys were made of the part of Saldanha Bay that lies to the landward of a line connecting Hoedjiespunt and Salamanderpunt (the ‘inner’ bay). Six distinctive subsurface units (Q-units) were recognized in the seismic records. They were correlated with a sequence of lithologically distinctive units encountered in boreholes drilled in the bay. At any instant in time the sea abrades the sea floor above a certain limiting depth and deposits materials below that depth. The incursion of the sea into an area therefore leads both to the removal and deposition of materials. The borehole results and the three-dimensional distribution of the Q-units in the bay indicate that the area has been affected by three abrasional/deposition cycles during the Late Pleistocene. During the earliest transgression the sea rose to a few metres above sea-level. During the second transgression it rose to −20 m. The last transgression took place when the sea...
TL;DR: In this article, the values of the natural resources of the Saldanha Bay-Langebaan Lagoon area are discussed in relation to the need for a management plan for nature conservation.
Abstract: Summary The values of the natural resources of the Saldanha Bay-Langebaan Lagoon area are discussed in relation to the need for a management plan for nature conservation.
TL;DR: A review of the Symposium on Research in Natural ScIENCes at the Salmanha Bay and the Langebaan Lagoon can be found in this paper, where the authors discuss their experiences.
Abstract: (1977). A REVIEW OF A SYMPOSIUM ON RESEARCH IN THE NATURAL SCIENCES AT SALDANHA BAY AND LANGEBAAN LAGOON. Transactions of the Royal Society of South Africa: Vol. 42, No. 3-4, pp. 211-214.