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This paper examines the notion that the fish stocks in Lake Kariba may now be suffering from the effects of climate change as air temperatures there have increased by about 2 °C since 1960. The ecosystem of Lake Kariba has changed dramatically since it was created in 1958, and the nutrients released by the collapse of the floating water-fern Salvinia molesta evidently brought about an increase in fisheries productivity that lasted for only a few years. This could account for some of the decreased catches attributed to climate change, although the data from the inshore fishery may be unreliable in any case. There is little evidence that climate change has affected the inshore fish stocks. On the other hand, research data from a fished area in Zambia and a closed area in Zimbabwe clearly reveal the impact of fishing. The catch per unit effort (CPUE) in gill nets decreased steadily in Zambia but the CPUE increased in Zimbabwe until it was around 2.5 times greater than in Zambia. The fishery for the introduce...

The sardine Limnothrissa miodon was introduced from Lake Tanganyika into the man-made Lake Kariba where it now supports a major fishery. The suggestion that this fish could be introduced into other African lakes has been strongly criticised and this paper outlines its effects on the ecology of Lake Kariba. It may have prevented an indigenous species from becoming a pelagic planktivore but the populations of the predatory tigerfish and some piscivorous birds increased following the sardine introduction. It has caused major changes, similar to those described elsewhere, to the zooplankton. The zooplankton biomass is now very low and it is not clear how it can maintain itself in the face of intense predation by the sardine. Cascade theory suggests that the sardines should have caused changes in the phytoplankton as well but there are too few data available to demonstrate this. The sardines may also have influenced the nutrient economy of the lake and contributed to the decline of the aquatic fern Salvinia molesta, which once covered large areas of the lake. It is concluded that while this species is a suitable candidate for stocking into man-made lakes its introduction into natural lakes is undesirable. This is especially so in Lake Malawi because the sardine's capacity to change the plankton population could threaten the lake's endemic species flocks.

The biomass of inshore fish in Lake Kariba, which is a large African man-made lake, was reassessed by sampling with explosives. This made it possible to sample a wide range of habitats, and fish biomass was found to be low along rocky, exposed shorelines. Because of this the total biomass of inshore fish was lower than earlier estimates indicated and may be

Arterial pH, Pco2 and whole blood standard bicarbonate were measured in surgical patients before, during, and after spontaneous or controlled pulmonary ventilation with nitrous oxide, oxygen and halothane. Relative increases in arterial Pco were accompanied by significant reductions in standard bicarbonate, indicative of a non-respiratory acid aemia. This effect may be attributable in part to differences between the log Pco2 equilibration lines for blood and for the whole organism. Small reductions in standard bicarbonate occurred over several hours of pulmonary overventilation in neurosurgical patients during induced hypothermia, and in the early postoperative period.