School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, WA, 99164-4236, USA.
Department of Environmental Studies, University of Southern California, Los Angeles, CA, USA.
Sci Rep. 2020 Nov 3;10(1):18885. doi: 10.1038/s41598-020-75635-z.
Shifting climate patterns may impose novel combinations of abiotic conditions on animals, yet understanding of the present-day interactive effects of multiple stressors remains under-developed. We tested the oxygen and capacity limited thermal tolerance (OCLTT) hypothesis and quantified environmental preference of the copepod Tigriopus californicus, which inhabits rocky-shore splashpools where diel fluctuations of temperature and dissolved oxygen (DO) are substantial. Egg-mass bearing females were exposed to a 5 h heat ramp to peak temperatures of 34.1-38.0 °C crossed with each of four oxygen levels: 22, 30, 100 and 250% saturation (4.7-5.3, 5.3-6.4, 21.2-21.3, and 50.7-53.3 kPa). Survival decreased at higher temperatures but was independent of DO. The behavioral preference of females was quantified in seven combinations of gradients of both temperature (11-37 °C) and oxygen saturation (17-206% or 3.6-43.6 kPa). Females avoided high temperatures regardless of DO levels. This pattern was more pronounced when low DO coincided with high temperature. In uniform temperature treatments, the distribution shifted toward high DO levels, especially in uniform high temperature, confirming that Tigriopus can sense environmental pO. These results question the ecological relevance of OCLTT for Tigriopus and raise the possibility of microhabitat selection being used within splashpool environments to avoid physiologically stressful combinations of conditions.
气候变化模式的转变可能会给动物带来新的非生物条件组合，但目前对多种胁迫因素相互作用的理解仍不够发达。我们检验了氧气和容量限制的热耐受（OCLTT）假说，并量化了栖息在岩石岸溅水池中的桡足类动物加利福尼亚桡足类的环境偏好，那里的温度和溶解氧（DO）昼夜波动很大。产卵的雌性被暴露在 5 小时的热斜坡中，温度达到 34.1-38.0°C，并与四个氧气水平中的每一个交叉：22、30、100 和 250%饱和度（4.7-5.3、5.3-6.4、21.2-21.3 和 50.7-53.3 kPa）。在较高温度下，存活率下降，但与 DO 无关。在温度（11-37°C）和氧气饱和度（17-206%或 3.6-43.6 kPa）的七个梯度组合中，量化了雌性的行为偏好。无论 DO 水平如何，雌性都避免高温。当低 DO 与高温同时发生时，这种模式更为明显。在均匀温度处理中，分布向高 DO 水平转移，特别是在均匀高温下，这证实了 Tigriopus 可以感知环境 pO。这些结果质疑了 OCLTT 对 Tigriopus 的生态相关性，并提出了在溅水池环境中使用微生境选择来避免条件的生理压力组合的可能性。
