We utilized an egg staining technique to measure the in situ fertilization success of two marine copepod species, Temora longicornis and Eurytemora herdmani from May to October 2008 in coastal Maine and correlated fertilization success with environmental conditions in their habitat. T. longicornis is a free spawning species that releases eggs into the ambient seawater after mating. In contrast, E. herdmani carries eggs in an egg sac until they hatch. The proportion of fertilized eggs within E. herdmani egg sacs was significantly higher than the freely spawned clutches of T. longicornis. This may be a result of the asymmetrical costs associated with carrying vs. spawning unfertilized eggs. T. longicornis frequently laid both fertilized and unfertilized eggs within their clutch. T. longicornis fertilization was negatively associated with chlorophyll concentration and positively associated with population density in their local habitat. The fertilization status of E. herdmani egg sacs was high throughout the season, but the proportion of ovigerous females was negatively associated with an interaction between predators and the proportion of females in the population. This study emphasizes that, in addition to population level processes, community and ecosystem level processes strongly influence the fertilization success and subsequent productivity of copepods.

Fertilization status of Eurytemora egg sacsThese data are from a survey conducted in the summer of 2008. The dependent variable is the fertilization status of Eurytemora egg sacs. The independent variables include several physical and ecological parameters measured at the time of the survey.eury.GLMM.fert.csvPresence of egg sacs for EurytemoraThese data are from a survey conducted in the summer of 2008. The dependent variable is the of egg sacs carried by Eurytemora females. The independent variables include several physical and ecological parameters measured at the time of the survey.eury.GLMM.eggsac.csvFertilization status of Temora eggsThese data are from a survey conducted in the summer of 2008. The dependent variable is the fertilization status of Temora egg clutches. The independent variables include several physical and ecological parameters measured at the time of the survey.temGLMM.fert.csv