Phytoplankton dynamics and cyanobacterial dominance in Murchison Bay of Lake Victoria (Uganda) in relation to environmental conditions

作者：Haande Sigrid^*; Rohrlack Thomas; Semyalo Ronald P; Brettum Pal; Edvardsen Bente; Lyche Solheim Anne; Sorensen Kai; Larsson Petter

来源：Limnologica, 2011, 41(1): 20-29.

DOI：10.1016/j.limno.2010.04.001

• Phytoplankton
• Nutrients
• Eutrophication
• Cyanobacteria
• Lake Victoria

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 (n=25) of total phosphorous > 90 mu g L(-1) and total nitrogen > 1100 mu g L(-1) 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 NO(3)-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.

• 出版日期2011-2