Data from: Between-population differences in multi-stressor tolerance during embryo development in the American horseshoe crab, Limulus polyphemus

The American horseshoe crab, Limulus polyphemus, is found along the Atlantic and Gulf of Mexico coasts in genetically-isolated populations. Eggs are laid in shoreline beaches that expose developing embryos to combinations of environmental stressors. Whether populations of L. polyphemus differ in multi-stressor tolerance had never been tested. We assessed the multi-stressor tolerance of L. polyphemus embryos from a population in Delaware Bay (DE) and determined whether these differed from the multi-stressor tolerance of embryos from a more southerly Florida Gulf Coast (FGC) population. We monitored the field sediment temperatures and determined multi-stressor tolerance of DE embryos, then compared these to published data for FGC embryos. For multi-stressor tolerance, we assessed development success of embryos in two-week exposures to 36 fully-factorial combinations of temperature (20, 25, 30, 35 °C), salinity (5, 15 and 34 ppt) and ambient O2 (5, 13 and 21% O2), followed by two-weeks in recovery conditions. Sediment temperatures in the DE site ranged from 9.5-46 °C, with extended periods exceeding 35 °C. Development success was similar between the DE and FGC populations in 14 of 26 multi-stressor combinations. The DE embryos were generally more successful in conditions that included high temperature or moderate hyposalinity, whereas the FGC embryos were generally more successful in conditions that included extreme hyposalinity. This suggests that although multi-stressor tolerances are generally similar between the two populations, specific differences exist that correlate more with differences in nest microenvironment than latitude.美洲鲎（Limulus polyphemus）沿大西洋及墨西哥湾沿岸分布，种群间存在遗传隔离。其卵产于沿岸海滩，发育中的胚胎会在此处经受多种环境胁迫因子的共同作用。此前尚无研究针对美洲鲎种群间的多胁迫耐受性差异展开验证。本研究对特拉华湾（Delaware Bay，DE）种群的美洲鲎胚胎多胁迫耐受性进行评估，并对比其与更南部的佛罗里达湾海岸（Florida Gulf Coast，FGC）种群胚胎的多胁迫耐受性差异。研究人员监测了DE种群原生栖息地的沉积物温度，并测定其胚胎的多胁迫耐受性，随后将结果与已发表的FGC种群胚胎相关数据进行对比。针对多胁迫耐受性评估，研究人员将胚胎置于温度（20、25、30、35℃）、盐度（5、15、34 ppt）、环境氧气含量（5%、13%、21% O2）共36种全因子组合的环境中暴露两周，随后将其置于恢复条件下培养两周，并统计胚胎发育成功率。DE种群原生栖息地的沉积物温度范围为9.5~46℃，且存在长时间超过35℃的时段。在26种多胁迫组合条件中，DE与FGC种群的胚胎发育成功率有14种表现相近。DE种群胚胎在高温或中度低盐胁迫的条件下发育成功率普遍更高，而FGC种群胚胎则在极端低盐胁迫的条件下表现更优。该结果表明，尽管两个种群的多胁迫耐受性整体相近，但二者间存在的特异性差异更多与巢穴微环境的差异相关，而非纬度梯度。