Macroalgae as Biofilters of Dissolved Inorganic Nutrients in an Integrated Mariculture Tank System in Zanzibar
Loading...
Date
2001
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A laboratory experiment was conducted to determine the capacity of themacroalgae Eucheuma denticulatum, Gracilaria crassa and Ulva reticulatato remove dissolved inorganic nutrients from finfish effluents in seriallyarranged tank systems. The aim was to determine the capacity ofmacroalgae which could be used in an integrated maricultre pond systemat Makoba, Zanzibar. Seawater from the reservoir entered the finfish tanksfirst, then drained through plastic pipes into the shellfish units and finallyinto the macroalgae units before being discharged back into the sea. Thewater residence time in each tank was 4 days. The performance of each ofthe different units was assessed in terms of total ammonia-N, phosphate-P and nitrate-N produced by finfish, and then, the removal of these nutrientsby shellfish and macroalgae biofilters. The levels of dissolved inorganicnutrients were highest in the finfish units and lowest in the macroalgaeunits. Increase in stocking density of macroalgae from 1g/l to 2g/l wasrelated to their increase in daily growth rates, specific growth rates andinorganic nutrient uptake rates. However optimum stocking densities werenot reached. Of the three inorganic nutrients, ammonia-N and phosphate-P was taken up by the macroalgae much more than nitrate-N. Ammonia-N removal efficiency in the system reached a maximum of about 63% at2g/l of Ulva reticulata whereas, phosphate-P and nitrate-N maximumremoval capacity were 58 and 54% respectively. Among the three species ofmacroalgae, Ulva reticulata seems to be the most efficient biofilter. It isconcluded that locally available macroalgae are good bioregulators of waterquality, thus can be applied in small scale mariculture activities and canalso generate income.
Description
Keywords
Citation
Mwandya, A.W., Mtolera, M.S.P., Pratap, H.B. and Jiddawi, N.S., 2001. Macroalgae as biofilters of dissolved inorganic nutrients in an integrated mariculture tank system in Zanzibar. In Marine science development in Tanzania and Eastern Africa. Proc. 20th anniversary conference on advances in marine science in Tanzania (pp. 159-170).