The long-term culture of the coccolithophore Pleurochrysis carterae (Haptophyta) in outdoor raceway ponds

The calcareous marine haptophyte algae, the coccolithophorids, are of global environmental significance because of the impact of their blooms on the carbon cycle. The coccolithophorid, Pleurochrysis carterae was grown semi-continuously in paddlewheel-driven outdoor raceway ponds over a period of 13 months in Perth, Western Australia. The mean total dry weight productivity of P. carterae was 0.19 g.L-1.d(-1) with cell lipid and CaCO3 contents of up to 33% and 10% of dry weight respectively, equivalent to an annual total biomass productivity of about 60 t.ha(-1) .y(-1) and 21.9 t.ha(-1).y(-1) stop total lipid and 5.5 t.ha(-1).y(-1)total calcium carbonate production. Throughout the culture period there was little protozoan contamination or contamination by other algae. The pH of the growth medium increased to pH 11 during the day and was found to be a useful variable for monitoring the state of the culture. A comparison of the growth of P. carterae and Dunaliella salina in the raceway ponds showed no significant differences between these two species with regard to areal total dry weight productivity and lipid content.