Abstract
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.
Highlights
In marine food webs, calanoid copepods perform vital ecosystem functions such as trophically connecting phytoplankton productivity to higher-level consumers including many commercially important species [1,2] affecting carbon export to the deep ocean in the form of sinking fecal pellets [3,4]
We found chlorophyll concentration to be significantly associated with T. longicornis fertilization success
Spawned clutches of T. longicornis contained a significantly lower proportion of fertilized eggs when compared to E. herdmani egg sacs (Fig. 1, F1,150 = 109, p,0.001, generalized linear model (GLM) quasibinomial distribution)
Summary
Calanoid copepods perform vital ecosystem functions such as trophically connecting phytoplankton productivity to higher-level consumers including many commercially important species [1,2] affecting carbon export to the deep ocean in the form of sinking fecal pellets [3,4]. The essential position that copepods hold in marine food webs has prompted investigators to examine factors limiting their productivity by measuring egg production rate [5,6] in relation to environmental factors such as temperature or food concentration [7,8]. Hatching failure in copepod production experiments can be the result of the production of resting eggs (which introduce a time lag into the hatching process), maternal assimilation of toxins and the production of unfertilized eggs. The ecological effect of resting eggs (i.e., fertilized eggs that remain dormant until favorable conditions induce hatching) on copepod population dynamics has received considerable attention in recent decades [14,15,16,17]. A central question remains as to the importance of fertilization limitation in reducing copepod productivity in nature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
