Implications of climate variability and change for African lake ecosystems, fisheries productivity, and livelihoods

Ogutu‐Ohwayo, R.; Natugonza, Vianny; Musinguzi, Laban; Olokotum, Mark; Naigaga, Shamim

doi:10.1016/j.jglr.2016.03.004

Cited by 44 publications

(24 citation statements)

References 81 publications

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“…Climate change is shifting species distribution, composition, and phenology. The viability of populations of the remaining species and overall biodiversity will most strongly depend upon the conservation of their habitats and the prevention of pollution of the water bodies [69], which intensifies under flooding conditions. Further investigation is thus required to definitively evaluate the impact of the 4.5 • C temperature warming on the flora and fauna expected by 2070.…”

Section: Projected Impact Of Climate Change and Variation On Other Ecmentioning

confidence: 99%

Projected Climatic and Hydrologic Changes to Lake Victoria Basin Rivers under Three RCP Emission Scenarios for 2015–2100 and Impacts on the Water Sector

Olaka

Ogutu

Said

et al. 2019

Water

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Rivers in the Lake Victoria Basin support a multitude of ecosystem services, and the economies of the riparian countries (Kenya, Tanzania, Uganda, Rwanda, and Burundi) rely on their discharge, but projections of their future discharges under various climate change scenarios are not available. Here, we apply Vector Autoregressive Moving Average models with eXogenous variables (VARMAX) statistical models to project hydrological discharge for 23 river catchments for the 2015-2100 period, under three representative concentration pathways (RCPs), namely RCPs 2.6, 4.5, and 8.5. We show an intensification of future annual rainfall by 25% in the eastern and 5-10% in the western part of the basin. At higher emission scenarios, the October to December season receives more rainfall than the March to May season. Temperature projections show a substantial increase in the mean annual minimum temperature by 1.3-4.5 • C and warming in the colder season (June to September) by 1.7-2.9 • C under RCP 4.5 and 4.9 • C under RCP 8.5 by 2085. Variability in future river discharge ranges from 5-267%, increases with emission intensity, and is the highest in rivers in the southern and south eastern parts of the basin. The flow trajectories reveal no systematic trends but suggest marked inter-annual variation, primarily in the timing and magnitude of discharge peaks and lows. The projections imply the need for coordinated transboundary river management in the future.is anticipated that climate change will continue to affect river hydrology and ecology through changes in rainfall distribution, soil moisture, river flows, and groundwater levels [11,12]. Recent fluctuations in river levels have had adverse impacts on the social, economic, and environmental well-being of many African communities [13,14]. Major changes in mean river discharge can have devastating impacts, particularly in Africa.Rainfall deficits of between 7% and 29% in East Africa between 1961 to 2010 led to sharp reductions in agricultural output and employment and also resulted in significant losses in Gross Domestic Product (GDP) [15]. Similar economic losses associated with drought conditions have occurred in West Africa, Australia, California, and Southern Africa [16][17][18][19][20]. Such losses emphasize the economic connection of climate and hydrology to water and sanitation, agriculture, fisheries, and energy sectors. Consequently, multiscalar present and future climate change studies are valuable for advancing scientific understanding and providing information for decision making in adaptation and mitigation strategies to deal with widening variability in river flows [21,22].Other threats to freshwater that are exacerbated by climate change include increased river siltation resulting from high soil erosion in the basin, recurrent destructive floods in the low-lying areas, riparian land encroachment, degradation of river banks, eutrophication, and proliferation of the invasive water hyacinth [23,24]. Increasing intensity and frequency of extreme climatic events pose ad...

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Section: Projected Impact Of Climate Change and Variation On Other Ecmentioning

confidence: 99%

Projected Climatic and Hydrologic Changes to Lake Victoria Basin Rivers under Three RCP Emission Scenarios for 2015–2100 and Impacts on the Water Sector

Olaka

Ogutu

Said

et al. 2019

Water

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“…Although Lake Victoria's Nile perch population is showing signs of decline, the fishery continues to be heavily exploited by a rapidly growing human population that is both economically and nutritionally dependent on this species (Taabu-Munyaho et al, 2016). Although the impacts of climate change in East Africa are uncertain, water temperature increases of 0.2-1.5°C have been detected in Lake Victoria since 1900 (Sitoki et al, 2010;Marshall et al, 2013), and air temperature increases of 1.3-4.5°C are expected by the end of the 21st century (Ogutu-Ohwayo et al, 2016). The Nile perch provides an excellent model to test thermal tolerance hypotheses for two reasons.…”

Section: Introductionmentioning

confidence: 99%

Elevated temperature and acclimation time affect metabolic performance in the heavily exploited Nile perch of Lake Victoria

Nyboer

Chapman

2017

Journal of Experimental Biology

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Increasing water temperatures owing to anthropogenic climate change are predicted to negatively impact the aerobic metabolic performance of aquatic ectotherms. Specifically, it has been hypothesized that thermal increases result in reductions in aerobic scope (AS), which lead to decreases in energy available for essential fitness and performance functions. Consequences of warming are anticipated to be especially severe for warm-adapted tropical species as they are thought to have narrow thermal windows and limited plasticity for coping with elevated temperatures. In this study we test how predicted warming may affect the aerobic performance of Nile perch (), a commercially harvested fish species in the Lake Victoria basin of East Africa. We measured critical thermal maxima (CT) and key metabolic variables such as AS and excess post-exercise oxygen consumption (EPOC) across a range of temperatures, and compared responses between acute (3-day) exposures and 3-week acclimations. CT increased with acclimation temperature; however, 3-week-acclimated fish had higher overall CT than acutely exposed individuals. Nile perch also showed the capacity to increase or maintain high AS even at temperatures well beyond their current range; however, acclimated Nile perch had lower AS compared with acutely exposed fish. These changes were accompanied by lower EPOC, suggesting that drops in AS may reflect improved energy utilization after acclimation, a finding that is supported by improvements in growth at high temperatures over the acclimation period. Overall, the results challenge predictions that tropical species have limited thermal plasticity, and that high temperatures will be detrimental because of limitations in AS.

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“…Despite the significant environmental changes encountered in the world largest lakes in the last twenty years [15,16,74], only three lakes showed significant changes in production over the study period. Only Great Bear and Great Slave lakes and Lake Tanganyika exhibited significant changes in the 2003-2018 period.…”

Section: Discussionmentioning

confidence: 92%

Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

Sayers

Bosse

Fahnenstiel

et al. 2020

Water

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Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m2/day to over 1100 mgC/m2/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends.

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Implications of climate variability and change for African lake ecosystems, fisheries productivity, and livelihoods

Cited by 44 publications

References 81 publications

Projected Climatic and Hydrologic Changes to Lake Victoria Basin Rivers under Three RCP Emission Scenarios for 2015–2100 and Impacts on the Water Sector

Projected Climatic and Hydrologic Changes to Lake Victoria Basin Rivers under Three RCP Emission Scenarios for 2015–2100 and Impacts on the Water Sector

Elevated temperature and acclimation time affect metabolic performance in the heavily exploited Nile perch of Lake Victoria

Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

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