Values were taken from the studies listed in Table 3. Only data where values were published in units of C, or where BP was measured by the uptake of ³H-leucine, were used. In the latter case a conversion of 1.5 kg C mol⁻¹³H-leucine was applied (Ducklow, 2003). Units for chlorophyll a and for BP and primary production, not included on the axes for clarity, are mg chlorophyll a m⁻³ and ng C l⁻¹ h⁻¹.