Productivity declines threaten East African soda lakes and the iconic Lesser Flamingo

Aidan Byrne; Emma J Tebbs; Peter Njoroge; Ally Nkwabi; Michael A Chadwick; Robin Freeman; David Harper; Ken Norris

doi:10.1016/j.cub.2024.03.006

Productivity declines threaten East African soda lakes and the iconic Lesser Flamingo

Curr Biol. 2024 Apr 22;34(8):1786-1793.e4. doi: 10.1016/j.cub.2024.03.006. Epub 2024 Apr 12.

Authors

Aidan Byrne¹, Emma J Tebbs², Peter Njoroge³, Ally Nkwabi⁴, Michael A Chadwick², Robin Freeman⁵, David Harper⁶, Ken Norris⁷

Affiliations

¹ Department of Geography, King's College London, London WC2B 4BG, England; Natural History Museum, Cromwell Road, London SW7 5BD, England. Electronic address: aidan.byrne@kcl.ac.uk.
² Department of Geography, King's College London, London WC2B 4BG, England.
³ National Museums of Kenya, Museum Hill Road, P.O Box 40658 - 00100, Nairobi, Kenya.
⁴ Tanzania Wildlife Research Institute, P.O Box 661, Arusha, Tanzania.
⁵ Zoological Society of London, Regent's Park, London NW1 4RY, England.
⁶ School of Geography, Geology & Environment, University of Leicester, University Road, Leicester LE1 7RH, UK; Freshwater Biological Association, Newby Bridge, Cumbria LA12 8BD, England.
⁷ Natural History Museum, Cromwell Road, London SW7 5BD, England.

PMID: 38614083
DOI: 10.1016/j.cub.2024.03.006

Abstract

Soda lakes are some of the most productive aquatic ecosystems.¹ Their alkaline-saline waters sustain unique phytoplankton communities²^,³ and provide vital habitats for highly specialized biodiversity including invertebrates, endemic fish species, and Lesser Flamingos (Phoeniconaias minor).¹^,⁴ More than three-quarters of Lesser Flamingos inhabit the soda lakes of East Africa⁵; however, populations are in decline.⁶ Declines could be attributed to their highly specialized diet of cyanobacteria⁷ and dependence on a network of soda lake feeding habitats that are highly sensitive to climate fluctuations and catchment degradation.⁸^,⁹^,¹⁰^,¹¹^,¹² However, changing habitat availability has not been assessed due to a lack of in situ water quality and hydrology data and the irregular monitoring of these waterbodies.¹³ Here, we combine satellite Earth observations and Lesser Flamingo abundance observations to quantify spatial and temporal trends in productivity and ecosystem health over multiple decades at 22 soda lakes across East Africa. We found that Lesser Flamingo distributions are best explained by phytoplankton biomass, an indicator of food availability. However, timeseries analyses revealed significant declines in phytoplankton biomass from 1999 to 2022, most likely driven by substantial rises in lake water levels. Declining productivity has reduced the availability of healthy soda lake ecosystems, most notably in equatorial Kenya and northern Tanzania. Our results highlight the increasing vulnerability of Lesser Flamingos and other soda lake biodiversity in East Africa, particularly with increased rainfall predicted under climate change.¹⁴^,¹⁵^,¹⁶ Without improved lake monitoring and catchment management practices, soda lake ecosystems could be pushed beyond their environmental tolerances. VIDEO ABSTRACT.

Keywords: Earth observation; Landsat; Lesser Flamingo; hydrology; limnology; productivity; remote sensing; soda lakes; species distributions; water quality.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Africa, Eastern
Animals
Biodiversity
Biomass
Climate Change
East African People
Ecosystem
Lakes*
Phytoplankton* / physiology