Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to environmental conditions
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Date
2011
Journal Title
Journal ISSN
Volume Title
Publisher
Limnologica
Abstract
Murchison Bay is a shallow embayment in the north-western part of Lake Victoria, strongly influenced
by urban pollution from the Ugandan capital Kampala. Two stations, representing the semi-enclosed
innermost part of the bay and the wider outer part of the bay, were sampled in the period from April
2003 to March 2004, in order to assess the phytoplankton community and the nutrient status in the
bay. Murchison Bay was highly eutrophic with average concentrations (n¼25) of total phosphorous
490 mg L1 and total nitrogen 41100 mg L1 in the inner part of the bay. The phytoplankton
community was dominated by a variety of cyanobacterial species and diatoms. Cyanobacteria were
dominant in the whole bay, whereas diatoms were more abundant in the outer part of the bay.
Moreover, the proportion of N-fixing species like Anabaena sp. was higher in the outer part of the bay,
whereas species like Microcystis sp. were more abundant in the inner part of the bay. The phytoplankton
community, especially in the outer part of the bay, may be influenced by light limitation. Low NO3–N
concentrations in the bay may also indicate a possible N-limitation, thus favouring growth of N-fixing
cyanobacteria. The open bay is, however, a complex system, and additional environmental factors and
loss processes most likely affect the phytoplankton community
Description
Keywords
Phytoplankton, Nutrients, Eutrophication, Cyanobacteria, Lake Victoria
Citation
Haande, S., Rohrlack, T., Semyalo, R. P., Brettum, P., Edvardsen, B., Lyche-Solheim, A., ... & Larsson, P. (2011). Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to environmental conditions. Limnologica, 41(1), 20-29. doi:10.1016/j.limno.2010.04.001