Growth of Gracilaria sp. (Gracilariales, Rhodophyta) in brackishwater ponds at different stocking densities.

Abstract

The specific growth rate (% per day) and net production rate (g per m² per day) of Gracilaria sp. cultivated in net cages in a brackishwater pond were determined at different stocking densities (200, 250, 300 and 350 g/net cage of 0.5 m²). The mean specific growth rates for the duration of the culture period were highest at stocking densities of 200 and 250 g per cage (P<0.05). The highest mean net production rate was obtained at a stocking density of 250 g per cage. The highest monthly mean specific growth rates and mean net production rates for all treatments were obtained in April, July and November; these were not significantly different from each other nor from the month of March (P>0.05), but were significantly different from the other months (P<0.05). Production was better during the dry season. Correlation analysis showed that water temperature, salinity, pH and total rainfall had no effect on the specific growth rate and net production rate (P>0.05). Results indicate that Gracilaria sp. can be grown in cages in brackishwater ponds at stocking densities of 200 and 250 g/net cage (400 and 500 g per m², respectively).