THE INTERRELATIONSHIP OF COPEPOD FECUNDITY AND MORTALITY

The fecundity of copepod species that carry attached eggs is commonly assessed by the egg ratio (eggs female(-1)), whereas the fecundity of broadcast-spawning copepods is assessed by measures of daily per capit a rates of egg production. Variability in these measures, when correct ed for temperature and allometric relationships with body size of adul t females, is often assumed to reflect variability in food supply in n ature and to thus provide an index of food limitation of population gr owth and of secondary production. We shaw that the measured fecundity of both brooding and broadcast-spawning copepods is affected by the mo rtality rate of adult females. We recognize three reproductive stages of adult female copepods: prereproductive, reproductive, and postrepro ductive. Mortality affects realized fecundity by shifting the relative abundance levels in these stages. Changes in mortality rates can gene rate substantial temporal variations in measured fecundity, even for c opepods that are unlimited by ambient food supply and reproduce al phy siological maximum rates. To correct for the effects of mortality on r ealized fecundity precise experimental determination of the reproducti ve schedule of adult females is needed, along with measures of mortali ty rates in nature.