UC San Diego

The hypothesis of resource-limitation of population growth of Pseudocalanus sp. was tested in Dabob Bay, Washington state. Five independent indices were inconsistent with the resource-limitation hypothesis: (1) interannual variations in abundance depend on the initial conditions, independent of within-year fluctuations in resources, (2) generation time in the field correspond to those for food-satiated copepods, (3) seasonal changes in prosome length are consistent with those for food-satiated animals, (4) ambient phytoplankton abundance nearly always meets or exceeds the critical concentration fo growth, (5) females reproduce continuously, exhibiting only damped seasonal changes in reproductive rate as assessed from a modified egg ratio method. The food limitation paradigm is not applicable to Pseudocalanus sp., for which predation is a more likely mechanism of population regulation.