Indications of the effects of climate change on the pelagic fishery of Lake Kariba, Zambia–Zimbabwe

Magadza, C. H. D.

doi:10.1111/j.1440-1770.2011.00462.x

Cited by 27 publications

(40 citation statements)

References 13 publications

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“…Analyses of climatic data for the middle Zambezi Valley indicate that warming around Lake Kariba is proceeding at a faster rate than predicted with regional models (Magadza 2010, 2011; Ndebele‐Murisa et al. 2011a,b).…”

Section: Introductionmentioning

confidence: 85%

Phytoplankton biomass and primary production dynamics in Lake Kariba

2012

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The present study examined spatial, seasonal and depth variations in phytoplankton biomass and primary production (PP), compared with those reported for other tropical African lakes, to determine whether or not measured phytoplankton changes might be linked to climate warming. The biomass of three major phytoplankton classes (Cyanophyceae; Chlorophyceae; Bacillariophyceae) and net PP were measured during the midwinter and midsummer at six different depths at 35 sampling sites distributed across the lake’s five basins. A more rigorous sampling regime was used in the fifth basin, with phytoplankton biomass and PP rates measured every second month over a 24 month period at six different depths at ten sampling sites located in riverine and lacustrine waters. Cyanophyceae, which displayed a gradient of decreasing biomass from Basins 2 to 5, contributed 69% of the total phytoplankton biomass in the lake’s five basins during summer. This percentage was approximately four times greater than that contributed by the Bacillariophyceae and about ten times greater than that contributed by the Chlorophyceae. During winter, Bacillariophyceae biomass was equivalent to that of the Cyanophyceae, but displayed an opposing gradient of increasing biomass from Basins 1 to 3, with a subsequent biomass decline from Basins 3 to 5. Chlorophyceae exhibited no distinct biomass gradient across the five lake basins, being undetectable during winter. The biomass of all three phytoplankton classes and the net PP varied in magnitude and direction monthly between the lacustrine and riverine waters, with increasing water depth and with no distinct seasonal patterns being evident. The monthly variations in biomass were related to the thermal stratification cycle, hydrological gradients and the extent of water mixing, being similar to those reported for other tropical African lakes. It is noteworthy that total phytoplankton biomass and PP in Lake Kariba have declined by about 95% and 50%, respectively, since the 1980s. These declines correspond to an upward shift in the depth of the thermocline, associated with an average temperature increase of 1.9 °C and a 50% reduction in the depth of the euphotic zone, since the 1960s.

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Section: Introductionmentioning

confidence: 85%

Phytoplankton biomass and primary production dynamics in Lake Kariba

2012

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“…Actually, such a rise in fish biomass is within the range of natural stock fluctuations for this small pelagic fish (Marshall, 1993), and given the estimation errors, it should not be interpreted as a long-term trend. More frequent surveys, complementary with estimates of fisheries catches, should be performed to better understand the natural and human-caused fluctuations, as recently illustrated in Lake Kariba (Magadza, 2011).…”

Section: Discussionmentioning

confidence: 99%

Is the fishery of the introduced Tanganyika sardine (Limnothrissa miodon) in Lake Kivu (East Africa) sustainable?

Guillard¹,

Darchambeau²,

Mulungula³

et al. 2012

Journal of Great Lakes Research

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Limnothrissa miodon, a small pelagic clupeid fish introduced at the end of the 1950s into Lake Kivu, became an important resource for the human populations of this area. The total stock of pelagic fish populations of this lake was estimated in 2008 by two hydroacoustic surveys, using an EK60 split-beam sounder (frequency 70 kHz). The total fish stocks were estimated to be approximately 5000 t in the rainy season and 6000 tons in the dry season. These values are similar to previous estimations performed in the 1980s. During 2008, the stock did not fluctuate throughout the seasons; however, the spatial distributions were different in the two hydrological seasons. Interestingly, the L. miodon stock has appeared to remain stable over the last two decades, which suggests that the pelagic fishery in Lake Kivu has not been overexploited and that it is sustainable.

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“…Mahere et al [76] also assert that between 1986 and 2011, the mean temperature of the lake rose by 0.7 • C, at a rate of 0.03 • C per year. Increases in ambient temperatures around the lake are known to translate into increases in lake water temperatures that have been shown to impact negatively on fish productivity, increasing the evaporation rates, lowering lake water levels, and also decreasing the amount of nutrients that are entering into the lake [31]. These observed and projected changes may affect fish productivity, resulting in low fish catches, lower incomes from fishing, and reduced availability of fish for diet as the sensitivity assessment shows SSF' high dependence on fish for diet.…”

Section: Linking Sensitivity With Exposure and Adaptive Capacitymentioning

confidence: 99%

Assessing the Sensitivity of Small-Scale Fishery Groups to Climate Change in Lake Kariba, Zimbabwe

et al. 2017

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Abstract:Climate change continues to pose threats to fisheries and fishery-dependent communities globally. Vulnerability to climate change is a function of exposure, sensitivity, and adaptive capacity. Sensitivity is largely determined by the differences in socio-economic conditions among communities, and conflicts over resources often exacerbate this sensitivity. This study aims to understand factors affecting the sensitivity to climate change. The objectives are twofold: first, to develop indicators affecting sensitivity and to determine how they affect sensitivity, second, to compare sensitivity of two small-scale fishing groups (fishing camps and fishing villages). The study used twelve indicators, which are categorized into two; the community characteristics and assets, and threats and conflicts. Results show that fishing camps are less sensitive to climate change than fishing villages since they have more varied livelihood sources, such as crop farming. This allows for more sources of income. Both groups experience conflict with other lake users and wildlife attacks, which amplify their sensitivity through the reduction of fishing grounds and the damaging of fishing gear. It also shows that both climate and non-climate factors affect sensitivity, and understanding this can help to increase adaptive capacity. The findings allow for formulation of policy recommendations to help strengthen the livelihoods of small-scale fisheries.

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Indications of the effects of climate change on the pelagic fishery of Lake Kariba, Zambia–Zimbabwe

Cited by 27 publications

References 13 publications

Phytoplankton biomass and primary production dynamics in Lake Kariba

Phytoplankton biomass and primary production dynamics in Lake Kariba

Is the fishery of the introduced Tanganyika sardine (Limnothrissa miodon) in Lake Kivu (East Africa) sustainable?

Assessing the Sensitivity of Small-Scale Fishery Groups to Climate Change in Lake Kariba, Zimbabwe

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