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

This study addresses carbon fixation and coccolith production and detachmen t in the cosmopolitan species Emiliania huxleyi (Lohmann) Hay et Mohler, un der conditions of nitrate limitation and high light typical of surface wate r in the ocean. Cells were grown under controlled growth conditions using n itrate-limited cyclostat cultures at four growth rates between 0.2 and 0.7 d(-1) in 1995. Both photosynthesis and calcification rates increased with g rowth 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. Esti mates of coccolith carbon content decreased with increasing cell growth rat es.