Carbon fixation and coccolith detachment in the coccolithophore Emiliania huxleyi in nitrate-limited cyclostats

This study addresses carbon fixation and coccolith production and detachment in the cosmopolitan species Emiliania huxleyi (Lohmann) Hay et Mohler, under conditions of nitrate limitation and high light typical of surface water in the ocean. Cells were grown under controlled growth conditions using nitrate-limited cyclostat cultures at four growth rates between 0.2 and 0.7 d⁻¹ in 1995. Both photosynthesis and calcification rates increased with growth rate. Coccolith dimensions remained constant at all cell growth rates. Specific rates of coccolith detachment also increased linearly with cell-specific growth rate at a ratio not significantly different from 1.00. Estimates of coccolith carbon content decreased with increasing cell growth rates. Received: 18 March 1997 / Accepted: 8 October 1998