Browsing by Author "Salum, Dotto Mbega"

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    The productivity of green and red strains of the carrageenophyte algae eucheuma denticulatum and kaappaphycus alvarezii (rhodophyta) in Zanzibar, Tanzania.
    (University of Dar es Salaam, 2006) Salum, Dotto Mbega
    The annual mean daily growth rate (DGR in percentage) of green (G) and red (R) strains of Kappaphycus alvarezii (Doty) Doty and Eucheuma denticulatum (Burman) Collins-Hervey were investigated at Jambiani and Uroa villages (in Zanzibar island) using an off-bottom monoline cultivation system with an aim of establishing their suitability for aquafarming in Tanzanian waters. Also investigated were carrageenan yield (CY as percentage of dry biomass) and properties of the phycocolloid as well as the thalli nitrogen status (TNS). It was found that the highest DGR (6.5-7.3) for R and G strains of K. alvarezii, were attained during the South- east monsoon (SEM) (July -September). Similarly, the highest DGR of the R and G strains of E. denticulatum (7.2-8.1) were also realized during the SEM (July) respectively. The lowest DGR (—3.1) — (—1.8) for the G and R strains of K. alvarezii and 1.1 - 1.3 for E. denticulatum were recorded during the North-east monsoon (NEM) (December - March), respectively. Although G strains had growth advantage over R strains during the favorable growth- season, the reverse was the case during the unfavorable season. Although the CY seasonality followed the DGR seasonality, the reverse was the case for the carrageenan gell strength as well as gelling and melting temperatures. The photosynthetic yield (PY as Fv/Fm) of all the strains used here was also investigated when growing in media regulated at 25°C, 30°C and 35°C. The highest and lowest PY values were found in plants growing in media regulated at 25°C and 35°C, respectively. From the results of the studies reported above, all the four strains investigated in this study appear to be suitable for commercial production of carrageenan in Tanzania. Although the green strains grow faster, the red strains of species, K. alvarezii and E. denticulatum have better capacities to survive in adverse environmental conditions (e.g. high solar radiation, high temperatures, etc) than the green strains. As synthesis of phycoerythrin requires high energy than chlorophyll, it is possible that such energy consuming processesin red strain could be useful as energy wasting processes in situations of high light where plant growth could be easily affected by phenomena such as photodamage and photoinhibition.