FIG. 4.

In situ relationships between daily photosynthetically available radiation flux and [³H]leucine incorporation (³H-leu_L) (a) and ¹⁴C- photoautotrophic production (¹⁴C-PP) (b) on nine Hawaii Ocean Time-Series cruises between March 2000 and May 2002. Line fits are least-squares nonlinear regressions. Equations describing the relationships are: [³H]leucine = 561 (1 − e^−1.1E) + 66, R² = 0.64, P < 0.0001; and photoautotrophic production = 511 (1 − e^−0.46E), R² = 0.47, P < 0.0001, where E is the in situ irradiance.