Browsing by Author "Mtolera, Matern"

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    Accumulation of Copper and Zinc and their Effects on Growth and Maximum Quantum Yield of the Brown Macroalga Padina Gymnospora. Western Indian Ocean J. Mar. Sci. 6(1):17-28 (2007)
    (2008) Mamboya, Florence A.; Pratap, Harish B.; Mtolera, Matern; Björk, Mats
    Accumulation and the effects of copper and zinc on the macroalga Padina gymnospora were assessed in the laboratory after artificial exposure to copper and zinc (separately or in combination). Exposure concentrations of copper used were 0, 25, 50, 100, 500 and 1,000 µg l-1. Concentrations of zinc exposure were 0, 50, 100, 250, 1,000 and 5,000 µg l-1. The simultaneous (or combined) addition of copper and zinc (Cu+Zn) involved 25+50, 50+100, 100+250, and 500+1,000 µg l-1. Accumulation patterns were determined by measuring tissue contents of copper and zinc, while the tolerance was assessed by measuring growth rate and photosynthetic performance, as maximum quantum yield (Fv/Fm). Furthermore, the influence of major nutrients (phosphates and nitrates) on algal-metal-accumulation was estimated after additions of nitrate (1, 10 and 20 mg l -1) and phosphate (0.1, 1 and 2 mg l-1). The data obtained showed that the accumulation increased linearly with the increase in metal concentration in the growth media. However, the presence of additional nitrate and phosphate reduced both the metal accumulation and their toxic effects. Both algal growth rate and maximum quantum yields were negatively affected in proportion to the increase in metal concentrations and exposure time. At exposures to 50, 100 and 500 µg l-1 copper, inhibition in growth was greater than 50%, while an exposure to 1,000 µg l-1of zinc was needed to cause the same effect on growth and Fv/Fm. Growth rate was a more sensitive indicator of stress than maximum quantum yield in response to exposure to copper and zinc.
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    Coastal resources utilization and conservation issues in Bagamoyo, Tanzania
    (1998) Semesi, A. K.; Mgaya, Yunus D.; Muruke, M. H. S.; Francis, Julius; Mtolera, Matern; Msumi, G.
    A study was carried out to provide information about the importance of the management of coastal resources in Bagamoyo, Tanzania. The results showed that the coral reefs at Mwamba Kuni and Mshingwi are the main fishing grounds for the artisanal fishermen. Trawlers compete and conflict with artisanal fishermen. The mangroves provide habitats for fish and other animals and are a source of fuelwood, charcoal, fishing stakes, building materials, and traditional medicines. Solar salt production is also an important activity. Although Bagamoyo depends on renewable resources, the harvesting rates of most resources are not known. Habitat destruction and overexploitation of resources have resulted in declining catches. There is unawareness among the resource users of the linkages between the various coastal ecosystems, but they do have vast traditional knowledge about the resources. In this article, we present the crustacean resources, fish, sea cucumbers, mangrove products, coral reefs, tourism, and salt production activities.
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    The Effect of Copper on the Daily Growth Rate and Photosynthetic Efficiency of the Brown Macroalga Padina Boergesenii
    (1999) Mamboya, Florence A.; Pratap, Harish B.; Mtolera, Matern; Björk, Mats
    The effect of copper (Cu) on the daily growth rate (DGR) and photosynthetic efficiency (PE) of the brown macroalga Padina boergesenii was studied under controlled laboratory conditions. The DGR was measured as an increase in fresh weight while the PE was measured as the ratio of variable to maximal chlorophyll fluorescence (Fv /Fm ). Padina boegesenii were exposed to 25, 50, 100 and 500mg Cu/l for 21 days. The DGR and PE of P. boergesenii decreased significantly with an increase in copper concentration in the growth media. This study shows that copper is acutely toxic to P. boergesenii at concentrations higher than 500mg Cu/l. Low concentration of copper is toxic to P. boergesenii after a prolonged exposure of 21 days. Similarly, exposure time has a significant negative effect on both DGR and PE.