Showing papers in "Transactions of The Royal Society of South Africa in 1982"
19 citations
TL;DR: Wound healing of the inhalant siphon of Donax serra, after amputation of the tip, is complete within 48 hours, and regeneration of the siphon tentacles commences, the tentacles growing to their original size within five days.
Abstract: SUMMARY Wound healing of the inhalant siphon of Donax serra, after amputation of the tip, is complete within 48 hours. Immediately after wounding, the inner and outer epithelial layers of the siphon wall are drawn together, at the tip only, preventing blood loss. The lesion is then plugged by connective tissue before being completely sealed by growth of new epithelium. Once the wound is sealed, regeneration of the siphon tentacles commences, the tentacles growing to their original size within five days.
19 citations
TL;DR: Monitoring of stocks of detritus, bacteria and phytoplankton and concentrations of inorganic nutrients in solution on an intertidal and subtidal rocky reef at Dalebrook in False Bay found numbers of bacteria were highest in summer and the amount of particulate matter in suspension was slightly higher than in summer.
Abstract: SUMMARY The seasonal variation in stocks of detritus, bacteria and phytoplankton and concentrations of inorganic nutrients in solution have been monitored on an intertidal and subtidal rocky reef at Dalebrook in False Bay. The results are compared with those from other inshore environments and their significance is discussed in relation to the large filter-feeding community on the reef. Concentrations of nitrate and silicate were lowest in summer. Phytoplankton standing stocks showed a similar trend; between October and March chlorophyll α concentrations were generally lower than 2 µg.l-−1. Large numbers of bacteria were encountered, the majority of which were free-living, rod-shaped cells; only 10 per cent of the cells were found attached to particulate matter. Numbers of bacteria were highest in summer. Despite the calmer seas in winter, the amount of particulate matter in suspension was slightly higher than in summer. The organic fraction, with an annual mean of 1,5mg.l-1, comprised approximately 39 pe...
12 citations
TL;DR: Altering the temperature within the range 10–20 °C has little effect on these responses, while the length of the exposure period has a greater effect.
Abstract: SUMMARY Solutions of both cadmium chloride and zinc chloride affect the oxygen intake of Bullia digitalis at 15 °C, the sensitivity to cadmium being about ten times greater than to zinc. Zinc concentrations above 1 ppm result in a lowering of oxygen consumption, uptake being reduced by some 40% at 2 ppm. Cadmium, on the other hand, increases respiration at levels between 0,1 and 0,7 ppm, there being an increase of 30% at 0,5 ppm. Above 0,6 ppm cadmium, oxygen uptake decreases rapidly and is 20% below normal at 0,75, 38% down at 1 ppm. Altering the temperature within the range 10–20 °C has little effect on these responses, while the length of the exposure period has a greater effect. Low concentrations of zinc do not alter the responses to cadmium but at higher concentrations of zinc the effect is additive.
6 citations
TL;DR: In this article, an analysis was made of dissolved and particulate matter in the surface waters of False Bay, and it was concluded that the large biomass of filter feeders on the intertidal and subtidal reef at Dalebrook depends primarily on energy derived from detritus produced in the inshore waters and associated bacterial decomposers.
Abstract: SUMMARY An analysis was made of dissolved and particulate matter in the surface waters of False Bay. Under conditions of strong, sustained south-easterly winds there was evidence of offshore upwelling of cooler, nitrate-rich water, which resulted in large phytoplankton standing stocks; chlorophyll α levels in excess of 10 μg.l−1 were recorded within 0,5 km of the shore. In the absence of these winds, nitrate concentrations and phytoplankton stocks were low in the offshore waters. Regardless of the wind, the particulate matter in shore was dominated by much unidentifiable detritus. It is concluded that the large biomass of filter feeders on the intertidal and subtidal reef at Dalebrook depends primarily on energy derived from detritus produced in the inshore waters and associated bacterial decomposers. The influence of upwelling, resulting in phytoplankton being driven in shore, is of minor importance to this benthic community.
5 citations
TL;DR: The early colonisation of the wreck of an obsolete naval frigate scuttled in 34 m depth in False Bay, South Africa showed a characteristic pattern of early settlement, rapid growth and decline towards the end of the first year as mentioned in this paper.
Abstract: SUMMARY Colonization of the wreck of an obsolete naval frigate scuttled in 34 m depth in False Bay, South Africa showed a characteristic pattern of early settlement, rapid growth and decline towards the end of the first year. Initial colonization was by barnacles followed by mussels, which became the most important organisms reaching a biomass of some 790 g.m-2 (wet mass) in places. After two years the mussel population had all but disappeared and the wreck appeared barren. A stable reef community was never established and the small number of species present—28 at its peak, declining to 10 after one year—was subject to catastrophic events both biotic and abiotic, which periodically destroyed large sections of the community.
5 citations