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Please use this identifier to cite or link to this item:
http://hdl.handle.net/1834/964
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| Title: | Standing Stock, Agar Yield and Properties of Gracilaria salicornia Harvested along the Tanzanian Coast |
| Authors: | Buriyo, A.S.
Kivaisi, A.K. |
| ASFA Terms: | Agar
Biomass |
| Issue Date: | 2003 |
| Publisher: | WIOMSA |
| Citation: | Western Indian Ocean J. Mar. Sci., 2 (2), p. 171-178 |
| Abstract: | Seasonal biomass variation and agar yield of G. salicornia (C. Ag.) Dawson from
Oyster Bay, Dar es Salaam, and Chwaka Bay, Zanzibar, were determined, and some properties
of the agar examined. Mean biomass and canopy cover values ranged from 21–60 g/m2 and 7–
20 %, respectively. The highest mean biomass and cover values were obtained during the SE
monsoon. Agar yield varied from 13.7 to 30.2 % (dry weight) and was highest during the dry
NE monsoon period. Alkali treatment generally reduced agar yield by 25–56 %. Gel strength of
the agar gels ranged between 118 and 251 g/cm2 and was significantly higher during the NE
monsoon period (t = 2.2; P = 0.04 and t = 8.9; P << 0.05) for samples collected from Oyster Bay
and Chwaka Bay respectively). Mean gel strengths of native agar samples (205 ± 45 g/cm2)
was about 42 % of that of the standard agar used. The 3,6-anhydrogalactose content was highest
during the rainy season (37.4–44.3 %) and tended to coincide with low gel strengths. Sulphate
content varied between 0.5 and 2.8 % in both populations. It was concluded that the best period
for harvesting G. salicornia for agar production in Tanzania is the dry (NE monsoon) period.
INTRODUCTION
Gracilaria is one of the algal genera from which
agar is extracted commercially (Lewis et al., 1990).
and the main source of agar in the world (Oliveira
et al., 2000). The algae are harvested by hand from
natural populations in Spain, Portugal, Morocco,
the Azores, California, Mexico, New Zealand,
South Africa, India, Chile and Japan (Armisen,
1995). Currently, the commercial mariculture of
agar-producing seaweeds is led by the production
of Gracilaria chilensis Bird, McLachlan et Oliveira
in Chile (Buschmann & Correa, 2001). The
seaweed has also been cultivated in China, Taiwan,
Namibia, Venezuela, Mexico (Armisen, 1995),
Indonesia and Vietnam (Oliveira et al., 2000).
Seven species of Gracilaria including G.
cornea J. Agardh (previously known as G. crassa
Harvey, Buriyo et al., in press), G. corticata J.
Agardh, G. arcuata Zanardini, G. salicornia, G.
edulis (J. Ag.) Silva, G. fergusoni J. Agardh |
| URI: | http://hdl.handle.net/1834/964 |
| ISSN: | 0856-860X |
| Appears in Collections: | Miscellaneous
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