Browsing by Author "Mbije, Emmanuel Nsajigwa"

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    Patterns in the distribution of hard corals in selected sites around Unguja Island, Zanzibar.
    (University of Dar es Salaam, 2001) Mbije, Emmanuel Nsajigwa
    A survey was conducted to describe the community structure of reefs in twelve selected reefs around Unguja Island, Zanzibar. The Line Intercept Transect method was used to quantify percentage cover of benthic lifeforms (hard coral, dead coral, soft coral, algae, etc.) and non-living substrate categories (rubbles, rocks and silt). Hard corals were identified to the generic level. Water temperature, salinity and water transparency were also measured. In total, number twenty-six coral genera were identified along the 145 transects examined. Twenty-five genera were members of the order Madreporaria, while one genus was from the order Milleporina. Friedman's test showed that there was a very significant difference in percentage cover among hard coral genera (x2r = 431.20, DF = 25, p < 0.001). Porites was most abundant followed by Acropora and Galaxea. Friedman's test also showed a significant difference in percentage cover of hard coral among sites (x2 r= 166.00, DF =1l, p < 0.001) and among depths (x2r = 8.52, DF = 4, p = 0.036). Coral cover was highest at Chumbe followed by Bawe North. The submassive forms of hard corals dominated the middle levels (1m and 3m), while massive forms dominated the reef flats and 10m. Acropora branching forms were common at 10m and 3m. The Shannon-Weaver index showed that generic diversity was highest at Chumbe, followed by Mnemba Northwest. The reefs near Zanzibar town, i.e. Chapwani, Changuu, Murogo, Bawe West and Bawe North all had similar, but intermediate diversity.