Abstract:
The last two decades have witnessed increasing episodes
of lesser flamingo die-offs in East Africa. Based
on data on phytoplankton composition, biomass, and
flamingo population density in three alkaline-saline
lakes of Kenya (Bogoria, Nakuru, and Oloidien) in
2001–2010, this study explored the link between sudden
flamingo deaths and fluctuations in algal food
quantity and quality. The phytoplankton biomass ranged
from 13 to 768 mg Æ L)1. Similarly, flamingo
numbers varied widely from <1,000 to >500,000 individuals
in the study lakes. The dominance of the cyanobacterium
Arthrospira fusiformis (Woron.) Koma´rek
et J. W. G. Lund was interrupted at irregular intervals
in each lake and replaced partly by populations of different
species of the nostocalean Anabaenopsis or by
the picoplanktonic chlorophyte Picocystis salinarum
Lewin. The populations of Anabaenopsis have the
potential of blocking the flamingo food filtration system
with their large and slimy colonies; moreover,
they are able to produce cyanotoxins. Estimates of flamingo
populations suggest that low flamingo numbers
coincided with periods of low algal food
quantity and ⁄ or poor quality. A food deficit can be
theorized to have two effects on the flamingos: (i) it
weakens them to the point of being susceptible to
attacks of infective diseases, such as the ones caused
by Mycobacterium avium and Pseudomonas aeruginosa,
and (ii) it predisposes them to poisoning by cyanotoxins
and pollutants, by reducing their capacity to handle
toxic substances. This study therefore concludes
that the challenges facing the flamingos are associated
with changes in their environment, which affect
food and water supply.
