Zooplankton production in the eastern tropical Atlantic Ocean: Net growth efficiency and P:B in terms of carbon, nitrogen, and phosphorus

Daily production rates in terms of carbon, nitrogen, and phosphorus are calculated for 0–100‐m mixed zooplankton from its measured excretion rates and net growth efficiency (K2). The latter was calculated from : phosphorus (N : P) and carbon:nitrogen (C:N) ratios of microzooplankton (50–200 µm) and mesozooplankton (200–5,000 µm), their excretion and assimilation efficiencies, and particulate food material over periods of several days at each of 21 stations representing several offshore ecosystems. Average K2 values for mesozooplankton were 0.372, 0.489, and 0.373 in terms of C, N, and P and 0.568 and 0.480 in terms of N and P for microzooplankton. P:B of microzooplankton (range: 34–230%) is 3.8 times that of mesozooplankton (15–62%). Calculations were also made for particular animals such as Salpa and Glaucus (nudibranch). The lack of a significant correlation between mesozooplankton P:B or K2 and the usual environmental factors is explained by the complexity of mixed populations. However, significant correlations with the N:P ratio of particulate food, or the assimilation number (that also refer to mixed populations), show that P:B and K2 values are not so erratic.