Effects of starvation on intermolt development in Calanus finmarchicus copepodites: a comparison between theoretical models and field studies

Campbell et al. (Deep Sea Research II 48 (2001) 531) have shown that there was a localized starvation event affecting Calanus finmarchicus on the sout hern flank of Georges Bank in April 1997. Growth and molting rates of this dominant copepod were reduced. We have used the morphology of tooth develop ment in field-collected samples to show that this starvation affected anima ls living continuously in the field, as well as those in Campbell et al.'s experimental tanks. Assuming a point of reserve saturation (PRS) response o f Calanus to food limitation, and correspondence between PRS and advance fr om the postmolt jaw facies, the proportion of individuals with postmolt jaw s should increase in all copepodite stages under starvation. Individuals th at have developed past PRS should molt to the next stage, acquiring postmol t facies. Thus, the fraction of postmolt jaws should increase, while the fr action of jaws in later phases should decrease. This was observed for a dri fter-marked station over five days. Numerical simulations of jaw phase dist ributions expected under full nutrition, and both total and patchy starvati on were generated from individual-based models of development. Proportions of copepodites in postmolt phase do not increase with full nutrition. A sim ulation of a total starvation event showed a marked increase in postmolts d uring food limitation, but the increase was more extreme than the field dat a. A modification of the starvation simulation, representing patchy feeding conditions, matched the level of increase of postmolt individuals in all s tages that was observed in the field samples. (C), 2000 Elsevier Science Lt d. All rights reserved.