Data from: Assessing the in situ fertilization status of two marine copepod species, Temora longicornis and Eurytemora herdmani; how common are unfertilized eggs in nature?

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.

本研究采用卵子染色技术，于2008年5月至10月间在缅因州沿海海域，对两种海洋桡足类（marine copepod）——长角哲水蚤（Temora longicornis）与赫氏真哲水蚤（Eurytemora herdmani）的原位受精成功率进行测定，并将受精成功率与其栖息地的环境条件开展关联分析。长角哲水蚤为自由产卵型物种，交配后会将卵子释放至周围海水中；与之相反，赫氏真哲水蚤会将卵子携带于卵囊中直至幼体孵化。赫氏真哲水蚤卵囊中受精卵子的占比，显著高于长角哲水蚤自由产出的卵团，这一差异或源于携带未受精卵子与释放未受精卵子所对应的不对称繁殖成本。长角哲水蚤的卵团中常同时存在受精与未受精卵子，其受精成功率与其栖息地的叶绿素浓度呈负相关，与当地种群密度呈正相关。赫氏真哲水蚤卵囊的受精状态在整个观测季均维持较高水平，但其怀卵雌体占比与捕食者压力及种群雌性占比的交互效应呈负相关。本研究表明，除种群水平过程外，群落与生态系统水平过程同样会显著影响桡足类的受精成功率及其后续种群生产力。