The Seagrass and Associated Macroalgae at Selected Beaches along Dar Es Salaam Coast
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Date
2001
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Abstract
Intertidal seagrasses and macroalgae were studied at a sewage-polluted
beach (Ocean Road) and a control site at Kunduchi beach, with a view to
assessing the effect of sewage discharge on macrophyte species
composition, abundance and above-ground biomass. A total of six species
of seagrasses were recorded at Ocean Road of which two, Thalassia
hemprichii and Cymodocea rotundata were the most abundant. Eight
species of seagrasses were recorded at Kunduchi. Two species, Syringodium
isoetifolium and Thalassodendron ciliatum were dominant in areas with
strong oceanic influence. Halodule wrightii and Halophila ovalis were widely
distributed in the two study areas. The mean biomass of seagrasses
between Ocean Road and Kunduchi beaches was not significantly different
(z = 4.053; p = 0.001; d.f. = 54). A total of 25 and 24 macroalgae species
were recorded at Ocean Road and Kunduchi beaches, respectively. The
total biomass of macroalgae was higher at Ocean Road than at Kunduchi
(t = 4.838; p>0.001). While the biomass of brown macroalgae was higher
at Kunduchi (t = 2.115; p = 0.039), that of red algae was similar at both
sites (t = 1.986; p = 0.052). Of the 11 epiphytic species of macroalgae
recorded on T. ciliatum at Kunduchi area, 73% were red algae, 18% green
algae and 9% brown algae. The dominant species on this beach was the
brown alga Cystoseira myrica. It was concluded that elevated levels of
ammonium at Ocean Road is a likely cause of the observed higher biomass
of green macroalgae at this site.
Description
Keywords
Seagrass, Macroalgae, Dar es Salaam Coast
Citation
Mgaya, BR Lugendo1 YD, and A. K. Semesi. "The seagrass and associated macroalgae at selected beaches along Dar es Salaam coast." In Marine science development in Tanzania and eastern Africa: proceedings of the 20th Anniversary Conference on Advances in Marine Science in Tanzania, 28 June-1 July 1999, Zanzibar, Tanzania, no. 1, p. 359. Institute of Marine Sciences, University of Dar es Salaam and Western Indian Ocean Marine Science Association, 2001.