This document summarizes how climate variability and change impact inland aquatic ecosystems, fisheries productivity, and livelihoods in Africa. It finds that temperatures have increased in African lakes since 1980s, affecting mixing dynamics and stratification. This caused shifts in aquatic organisms and fisheries toward faster growing species. Communities have adapted fishing methods and diversified livelihoods. However, more policy interventions are needed to support adaptation, mitigate impacts, and incorporate climate change into management.

1. Ogutu-Ohwayo R., Natugonza V., Musiguzi L., Kitabona J.
National Fisheries Resources Research Institute (NaFIRRI),
P. O. Box 343, Jinja, Uganda. .
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The Response of Inland Aquatic Ecosystems,
Fisheries Productivity and Livelihoods to
Climate Variability and Change:
Lessons from Africa

2. Vulnerability of fisheries resources
 Africa is endowed with aquatic
ecosystems which are important
sources of food, employment and
income.
 The diversity and quantity of fish in
these systems has decreased due to
over-exploitation, pollution, invasive
species, habitat degradation, and climate
variability and change.
 However the response of aquatic
ecosystems, resources and livelihoods to
climate variability and change has
received limited attention.
 We review literature from Africa to
demonstrate how aquatic ecosystems,
productivity, fisheries and livelihoods
respond to increasing variability and
change in climate to guide policy. 2

3. We predict that:
Lake area, depth, circulation, stratification, loading and
recycling of nutrients and oxygen will shift between states with
variability and change in climate.
In turn, the composition and abundance of aquatic organisms,
including fishes will shift to those that can persist, adjust or
exploit the changed conditions.
 This will make it necessary for communities to adapt to build
their resilience in order to sustain livelihoods;
 Existing policies will have to be adjusted and additional ones
put in place to address the changes and support adaptation.
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Theory of Change

4.  Temperatures of the deep African Great lakes increased by
0.2-1.5oC over the 20th century and those around shallow
lakes increased by 0.02°C - 0.03°.
 Wind speed over the lakes has changed depending on
geographic location and changed the mixing dynamics and
stratification regimes of the lakes.
 Rainfall has varied resulting into episodes of floods and
droughts and changes in lake levels, depths and area.
 The changes appear to have intensified around 1980s.
 The changes have contributed to changes in mixing
dynamics, productivity of the lakes, and affected livelihoods
making it necessary for communities to adapt to build
resilience so as to sustain livelihoods.
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Changes in Climate Variables

5. Changes in Temperature and Windspeed
The temperature over Lake Victoria increased consistently after
1980s while wind speed increased since 1976 to around 2000
and decreased (MacIntyres 2013) suggesting that some climate
factors will shift between states with similar changes in
productivity processes.

6. Temperatures around Lake Wamala increased consistently by
0.02 to 0.030C annually since 1980s and rainfall was generally
above average since the 1990s in line with global predictions
and those for the East African region
Changes in Temperature and Rainfall
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7. Area and Depth of the Lakes
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The area of Lake Chad decreased by 90% & depth from 7 to
1.5m; Area of Wamala from 250-100 km2 & depth from 4.5-1.5;
The area of Lake Chilwa has varied and in some cases virtually
dried up and; The depth of deep African lakes has manifested
decreasing trends with changes in climate variables.
Chad Wamala

8. Decrease in Depth of Deep African the Lakes
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The depth of African lakes Kyoga, Albert & Edward (Swenson &
Wahr 2013) and Victoria and Kyoga has decreased.

9. Decrease in Diversity of Fishes
Shrinking of Lake Chad was accompanied by a decrease in the
number of fish species from about 40 to 15 (Leveque, 1995).
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10. Fluctuations in rainfall around Lake Wamala were closely
associated with changes in fish catch.
Fish Catches
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11. Fluctuations in lake level of Lake Chilwa were closely
associated with changes in fish catch (Allison et al., 2007).
Fish Catches
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12. Life History Parameters of Nile tilapia
The changes in area
and depth of Wamala
were accompanied by
changes in mean
length and size at first
maturity of the Nile
tilapia before 1980 and
after 2000
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13. The mean weight of Kapenta in Lake Kariba decreased with
increasing temperature especially after 1980s and appears to
have increased after around 2000 (Ndebere-murisa et al.,
2011).
Weight of Fish
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14. Physical and Chemical Conditions and
Productivity
Paleolimnologic observations show that the deposition of P,
biogenic Si, and organic carbon increased more rapidly after
1980s and was later followed by increases overall fish catches
(Hecky et al 2010).
The concentration of P in
Lake Victoria doubled;
dissolved silicon
decreased ten times;
Chla increased fivefold;
thermal stratification and
anoxia increased and
water transparency
decreased during 1990s
(Hecky 1993)

15. The concentration of Chl a in Lake Victoria which increased from
around 1985 to 2000 decreased thereafter around 2000 while
water transparency improved (Sitoki et al 2010). This was
attributed to changes in mixing dynamics (Marshall 2013) which
supports our prediction that productivity processes will shift
between states with changes in some climate variables such as
wind speed.
Shifts in Chl a and Water Transparency
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16. Changes in Invertebrates Communities
The zooplankton in Lake Victoria
changed from dominance of
larger calanoid copepods and
cladocerans before 1950s to
smaller cyclopoid copepods
during 1990s; and benthic
invertebrates from chironomids
and chaoborid midges and the
prawn (Caridina nilotica)
(Ndawula ,1993)

17. There have also been a
shift in the contribution of
small pelagic clupeids in
lakes Victoria, Kyoga and
Albert to contribute up to
80% of the fish catches
after 1980s in line with the
predictions by FAO that
climate change will shift
fisheries to small and
faster growing
opportunistic species.
Shifts in Fish Species Composition
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18. Water hyacinth
infestation occurred
suddenly and
increased rapidly in
lakes Victoria and
Kyoga in 1980s and
attained peak cover in
1998 after which its
biomass collapsed
suddenly during the
last half of 1998.
Appearance of Aquatic Weeds

19. Warming of surface waters of
Lake Tanganyika was
accompanied by changes in
mixing dynamics and plankton
composition but was unlike
Victoria followed by a 20%
decrease in primary
production and a 30%
decrease in fisheries yield
(O’Reilly et al., 2003)
suggesting that the impacts of
climate change will vary
between aquatic systems
depending on the influence of
climate variables on mixing
regimes.
Primary Production and Fisheries Yield
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20.  In Lake Wamala changes in climate factors were associated with
loss of gear, damage to landing sites and loss of lives and affected
fish catches and consumption;
 Flooding of Lake Chilwa in 1991 resulted in death of >500 people
and the decline in catches to zero deprived fishers on fishing
opportunities, income and livelihoods.
 On Lake Kariba, the decline in mean weight of Kapenta and catch
per unit effort related to climatic factors affected the benefits of
fishers from fishing and interfered with fishing operation.
 On Lake Tanganyika, the 30% reduction in fish yield reduced
catches for fishers, loss of revenue and interference with fishing
operations.
 On Lakes Victoria and Albert there has been an increase in less
valuable clupeids
Impacts on Livelihoods
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21.  In Lake Wamala fishers adapted by reverting to non-fishery
activities, increasing time and changing fishing ground and target
species;
 More innovative fishers on Wamala diversified to growing high
value crops such as oranges, pineapples and tomatoes which
resulted into higher incomes than they used to get from fishing.
 On Lake Chilwa people adapted to flood by shifting homes to
higher ground, seeking off-farm employment, and diversifying their
food sources to include wild animals;
 On lakes Victoria and Kyoga fishers increasingly shifted from
gillnets to mosquito seine nets with increase in small pelagic fishes.
 Mitigation measures on Lake Wamala included protecting
wetlands, planting trees and mulching garden
Adaptation and Mitigation Measures
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22.  Increase in unsustainable fishing practices use of illegal gears
and fishing practices.
 Degradation of critical aquatic habitats cultivating and grazing up
to lake shores and farming lake floors.
 Excessive use fertilizers and pesticides which can degrade the
fish habitat, cause fish kills and can even render the fish
unsuitable for human consumption.
Challenges accompanying adaptation
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23. 23
. On Lake Chilwa the main constraints included:
Increased population;
Reduced opportunities for off-farm activities;
Limited access to improved crop varieties; and
Poor social services, and
On Lake Wamala they included:
Limited credit facilities, awareness, and land;
Limited availability of appropriate planting materials;
Lack of affordable irrigation facilities;
Inadequate law enforcement; and
High dependence on only fishing as a source off
livelihood
Constraints to adaptation

24. The policies interventions that need to be implemented
support adaptation and mitigation include:
 Controlling human population increases;
 Controlling nutrient loading;
 Managing wetlands, river banks and lake shores;
 Managing emerging fisheries, and invasive species;
 Managing land use, land use change, and agricultural
practices;
 Promoting aforestation and reforestation;
 Promoting adaptation and mitigation measures; and
 Incorporating climate change in existing policies
Policy Interventions
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25.  Evidence from literature suggests that the changes in climate
are accompanied by shifts in aquatic productivity processes,
fisheries and livelihoods.
 The changes became more pronounced after 1980s but shifted
around 2000 supporting our prediction that aquatic productivity
processes will shift between states with climate variables.
 The impacts are also location specific.
 There is need to examine the direction and consequences of the
increasing variability and change in climate on aquatic
productivity processes, fisheries, and livelihoods of specific
aquatic systems, and to develop and promote appropriate
adaptations and mitigations strategies and policies that integrate
climate science in management of the resources.
Conclusion and Recommendations
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