摘要:

Wound healing of the inhalant siphon ofDonax 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.

ISSN:0035-919X    

DOI:10.1080/00359198209519137

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

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.

ISSN:0035-919X    

DOI:10.1080/00359198209519138

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

For each month of the year rainfall totals are regressed on sea-level pressure which has been redefined, using principal component analysis, as a set of uncorrelated pressure fields. This new set has been used, in the multiple linear regression procedure, as independent variables. It is shown that rainfall and sea-level pressure are related, linearly, in a way that is spatially dependent. The pattern of this association also varies from month to month but does so in a gentle way across the country. The strength of the relationship does not necessarily follow the seasonal march of rainfall across the country.

ISSN:0035-919X    

DOI:10.1080/00359198209519139

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

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 per cent of the total. Detritus was the largest source of organic material on the reef, averaging 1,2 mg.ℓ-1. Much of this detritus is thought to have originated from the large seaweed community growing along the coast, although microscopic examination showed that most of this material was in an advanced state of decomposition and there was little fresh, easily identifiable plant material. In view of the small phytoplankton standing stocks in the vicinity of the reef it appears to be detritus and associated bacteria which support the large biomass of filter feeders.

ISSN:0035-919X    

DOI:10.1080/00359198209519140

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

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−1were 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.

ISSN:0035-919X    

DOI:10.1080/00359198209519141

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Solutions of both cadmium chloride and zinc chloride affect the oxygen intake ofBullia digitalisat 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.

ISSN:0035-919X    

DOI:10.1080/00359198209519142

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198209519143

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198209519144

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor