Effect of starvation on development and survivorship of naupliar <i>Calanus pacificus</i> (Brodsky)

Abstract

In the marine planktonic copepod, Calanus pacificus (Brodsky), survivorship and development rate during the remaining naupliar stages were reduced when initial feeding was delayed for ~ 10 h after molting into naupliar stage III (NIII). In otherwise well-fed stages NIII-NVI, development and survivorship were reduced after starvation periods > 6 h and > 14 h, respectively. Molting rate and survivorship were lower in response to transient starvation than in response to constantly low food supplies. Stage NV was the least sensitive to transient starvation, while stages NIII and NVI were the most susceptible. Molting rates were reduced even after abundant food was subsequently provided. Thus, ambient food concentration at the time a population is sampled may not be an adequate index of future cohort success. Estimates of fine-scale to micro-scale particle distributions in situ suggest that NIII, the first feeding stage, is the instar most likely to experience short starvation periods if hatching occurs well below phytoplankton-rich strata.