Lake Turkana, Kenya is an understudied desert lake that receives over 90% of its inflow from the Omo River in Ethiopia. The volume and patterns of inflow from this river influence the lake’s chemistry and productivity, as well as the availability of habitat and the breeding migrations of its fishes. Lake Turkana is at the precipice of large-scale changes in ecological function due to climate change and economic development along the Omo River, including the construction of massive dams and irrigation projects. Upstream development will reduce the volume of water entering the lake and dampen the lake’s ecologically crucial seasonal flood pulse. These changes will almost certainly impact the lake’s fisheries at a time when they are becoming increasingly
important to local livelihoods and national food security. This dissertation considers how the lake’s fish communities, which have not been well studied since the 1980’s, will respond to upstream development. Using data from satellite altimetry and local fisheries organizations, this study showed that water levels and their fluctuations are key drivers of fisheries productivity in the system. Using geographic information systems, water levels were shown to alter the distribution of habitat types and seasonal flood pulses to determine the extent of productive dynamic littoral habitat in the lake. Stable isotope analysis and a breeding vulnerability index for the top fishery species in the system showed that while some species of economic importance are ecologically flexible (e.g. Oreochromis niloticus. Lates niloticus), others (e.g. Tilapia zillii, Labeo horie) are highly sensitive to changes in habitat availability and food web structure. Lastly, a synthesis of published food web models for African lakes showed that altering the magnitude of water level fluctuations of these lakes has implications for their productivity, fish diversity, and the complexity, efficiency and connectivity of their food webs. Taken together, these studies suggest that upstream development will have extensive negative consequences for Lake Turkana and its fisheries. Although recommendations are made regarding minimizing impacts to the lake, more research must be conducted to comprehensively inform water resource
management in the region.
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... Kolding (1989;1992) also provided an update on the ichthyofaunal list that focused mainly on the lake's fisheries. Recent studies on the ichthyofaunal diversity of the Omo River and Lake Turkana on the Ethiopian side have been undertaken as part of Joint Ethio-Russian Biological Expedition (JERBE) and PhD projects (Golubtsov and Darkov, 2008;Prokofiev and Golubtsov, 2013;Gownaris, 2015;Wakjira, 2016;Wakjira and Getahun, 2017). ...
... A snapshot update on the status of the fish stocks was conducted by Muška et al. (2012) in the open water of the central part of the lake through a hydroacoustic survey and supplementary gill net investigation. Around this time, Gownaris (2015), Gownaris et al. (2015) and Gownaris et al. (2017) collected data on the lake's food web and water quality as part of her PhD study from 2011 to 2013. From the limited data that do exist, many ecologically unique and scientifically interesting characteristics have emerged, such as the intimate ties between the lakes' drastic water level fluctuations and its fauna (e.g., tilapia production: Kolding, 1993a; primary productivity: Tebbs et al., 2019; overall fisheries catch: Gownaris et al., 2017), the semi-saline chemistry of the system, the low flora and fauna diversity for its size, a mid-scattering layer of small endemic characins (Alestes spp.), and intermittent phenomenal peaks in production of tilapia (Oreochromis niloticus) (Kolding, 1993a). ...
Lake Turkana, located in northwestern Kenya and south-western Ethiopia, is Africa’s fourth largest lake and the world’s largest permanent desert lake. The lake lies in a closed basin and its limnology, ecology, and fisheries are driven by seasonal cycles of flooding from the Omo River, which provides more than 90% of the lake’s inflow. Lake Turkana is a unique ecosystem and is home to at least 79 fish species (12 endemic), the world’s largest remaining population of Nile crocodile, and hundreds of resident and migratory bird species. The lake has considerable fisheries resources that contribute to food security, employment, and the general wellbeing of local communities. Lake Turkana is also the least studied of the Great Lakes of Africa, due to its remoteness, the absence of necessary scientific infrastructure, and the scarcity of trained personnel in the field of aquatic sciences and fisheries in the region. Here, we present a review based on the available literature and on expert discussions and surveys to synthesize current knowledge, research gaps, and opportunities for increasing our knowledge on this unique ecosystem. Our literature review showed that there is a marked lack of interdisciplinary and applied research on Lake Turkana, and that much of the work published on the system (63.3%) focuses on previous geological periods rather than the current state of the ecosystem. We highlight four critical steps that need to be taken to improve research into this system: local capacity building, consistent monitoring and data sharing, sustainable financing, and strengthened collaborative networks.
From 1964 to 1990, the yearly mean air temperature
has increased by 0.7 °C in Bujumbura (northern end of Lake
Tanganyika) and 0.9 °C at Mbala (southern end of Lake
Tanganyika) while winds speed have decreased. The
epilimnion showed a weaker tilting up toward the north
causing nutrient rich layers there to be closer to the
surface where average transparency decreased. A weaker
tilting of the thermocline was related to decreased
upwelling in the south and less warm water accumulation in
the north, as a result of reduced winds speed. When the SE
winds stopped blowing, less epilimnion waters than usual
moved to restore equilibrium. This could be related to a
lower dynamics of the lake.
The catches of Stolothrissa tanganicae in the south of the
lake have declined since the early 1980s. This could be
explained by less favourable conditions for reproduction,
increased predation and fishing. The catches of those
fishes in the south are mainly seasonal (during the
upwelling season). It is possible also that the observed
decrease of their catches is tied with decreased upwelling
intensity and less plankton production during that period.
The zooplankton is now sparser in the south of the lake
(Kurki and Vuorinen, 1994).
During the last 15 years L. stappersii catches have
increased in the south. The correlation between catch per
unit of effort (CPUE) of L. stappersii and the transparency
there was significant (P< 0.01) in 1993-94. The increased
transparency during the wet season in the south probably
enhanced visual predation by L. stappersii. This species
was often absent from the catches in the north of the lake
where transparency has been reduced by 36 % from the 1955-
57 values.
A "teleconnection" between the El Niño-Southern Oscillation
(ENSO) and the regional air temperature was found. A
significant correlation was found between ENSO and catches
of the clupeids and L. stappersii. ENSO may be predicted
18 to 20 months in advance. Therefore an improved
understanding of regional climate linked to limnological
and fisheries changes, may provide a method of forecasting
fisheries yields for the main pelagic species of Lake
Tanganyika.
Located in the “cradle of mankind” of the East African Rift Valley, Lake Turkana is distinguished as both the world’s largest permanent desert lake and alkaline water body. With a surface area of about 7,560 km2, Lake Turkana is a highly pulsed, variable system as a result of its closed-basin nature, arid surroundings, and its strong dependence on River Omo for the majority of its inflow, which originates as rainfall over the Ethiopian highlands. In this article we describe the lake’s unique ecosystem and associated vicissitudes, diverse habitats and incredible biodiversity, and ecosystem services. Although parts of the lake and lower Omo Delta have been zoned as an international biosphere reserve, Lake Turkana and the region are facing immense threat from anthropogenic activities. A combination of external factors (hydropower dams, irrigation schemes, climate anomalies) and internal drivers (demography, economic growth) will strongly impact the Lake Turkana basin over the next decade. In turn, this will have significant negative consequences on resource productivity and the wellbeing of local communities.