Abstract

Copepods dominate the zooplankton communities and support large fisheries within the Humboldt Current System (HCS). Using detailed data of live/dead compositions, along with stage durations and molting rates, we derived, for the first time, both predatory and non-predatory mortality rates of the 3 dominant copepod species - Paracalanus cf. indicus, Acartia tonsa and Calanus chilensis- within the HCS and examined their relationships with environmental factors. Predatory mortality rates of all 3 species increased linearly with developmental stage, and hence body size, indicating top-down control by predators that prefer larger prey. Intrusion of oxygenpoor water via upwelling and low chlorophyll a concentration were linked to increased nonpredatory mortality rates of P. cf. indicus and A. tonsa, whereas non-predatory mortality rates of C. chilensis were positively correlated with temperature. On average, non-predatory mortality accounted for 34.8-46.3% of the total mortality among the 3 species. Changes in upwelling intensity caused by climate change may alter the extent and patterns of predatory and non-predatory mortalities in the HCS copepod communities.