The physiology of invertebrates inhabiting many coastal ecosystems is challenged by strong temporal fluctuations in salinity. We investigated how food availability influences vital rates in the tropical cyclopoid copepod Apocyclops royi subjected to different salinities (5–32 PSU). We hypothesized that (i) mortality decreases and egg production rate increases with food availability; (ii) under suboptimal salinity, mortality increases and the egg production rate is reduced and (iii) the threshold concentration for egg production (the lowest food concentration where egg production is initiated) shifts to higher food concentrations when challenged by salinity. Surprisingly, A. royi survived, ingested food and produced eggs at all tested salinities. Mortality rate was, however, dependent on salinity level, but not on food availability. Mortality increased (~12% h⁻¹) during short-term (1 h) salinity acclimatization to 5 PSU and during the following 24-h incubations (~5% d⁻¹) compared with higher salinities. Feeding and egg production rates increased with food availability up to an optimum at all salinity levels, with no effect of salinity on the lowest food concentration initiating egg production. This reveals a high-salinity tolerance by A. royi and may partly explain why this particular copepod is so successful compared with its congeners in occupying extreme habitats.

中文翻译：

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在盐度变化的情况下，资源的可获得性会影响热带co足类Apocyclops royi（Lindberg，1940）的生命率吗？

盐度的剧烈时间波动挑战了居住在许多沿海生态系统中的无脊椎动物的生理。我们调查了在不同盐度（5–32 PSU）下，食物的可获得性如何影响热带摆线小足pe足类罗汉果的生命率。我们假设（i）死亡率随着食物供应的增加而降低，产蛋率增加；（ii）在盐度欠佳的情况下，死亡率增加，产蛋率降低，并且（iii）受盐度挑战时，产蛋的阈值浓度（开始产蛋的最低食物浓度）转移到较高的食物浓度。令人惊讶的是，A。royi在所有测试的盐度下都能存活，摄取食物并产生卵。但是，死亡率取决于盐度水平，而不取决于食物的可获得性。与盐度较高相比，在短期（1 h）盐度适应至5 PSU和随后的24小时孵育（〜5％d ^-1）期间，死亡率增加（〜12％h ^-1）。在所有盐度水平下，随着食物供应量的增加，摄食和产蛋率提高到最佳水平，而盐度对最低的食物浓度不会产生卵的影响。这表明罗伊拟南芥具有很高的耐盐性，并且可以部分解释为什么这种co足类动物与其同类动物相比在占据极端栖息地方面如此成功。