Physiological responses and scope for growth upon medium-term exposure to the combined effects of ocean acidification and temperature in a subtidal scavenger Nassarius conoidalis

Physiological responses (ingestion rate, absorption rate and efficiency, respiration, rate, excretion rate) and scope for growth of a subtidal scavenging gastropod Nassarius conoidalis under the combined effects of ocean acidification (pCO2 levels: 380, 950, 1250 µatm) and temperature (15, 30 °C) were investigated for 31 days. There was a significant reduction in all the physiological rates and scope for growth following short-term exposure (1-3 days) to elevated pCO2 except absorption efficiency at 15 °C and 30 °C, and respiration rate and excretion rate at 15 °C. The percentage change in the physiological rates ranged from 0% to 90% at 15 °C and from 0% to 73% at 30 °C when pCO2 was increased from 380 µatm to 1250 µatm. The effect of pCO2 on the physiological rates was enhanced at high temperature for ingestion, absorption, respiration and excretion. When the exposure period was extended to 31 days, the effect of pCO2 was significant on the ingestion rate only. All the physiological rates remained unchanged when temperature increased from 24 °C to 30 °C but the rates at 15 °C were significantly lower, irrespective of the duration of exposure. Our data suggested that a medium-term exposure to ocean acidification has no effect on the energetics of N. conoidalis. Nevertheless, the situation may be complicated by a longer term of exposure and/or a reduction in salinity in a warming world.

本研究针对潮下带食腐腹足类软体动物秀丽织纹螺（Nassarius conoidalis），在海洋酸化（二氧化碳分压，pCO2）水平分别为380、950、1250 µatm，以及温度分别为15、30 °C的复合胁迫下的生理响应（摄食率、吸收速率、吸收效率、呼吸速率与排泄率）及生长潜力开展了为期31天的实验研究。短期暴露（1-3天）于高pCO2环境后，除15 °C与30 °C下的吸收效率，以及15 °C下的呼吸速率与排泄率外，所有生理速率及生长潜力均出现显著下降。当pCO2从380 µatm升高至1250 µatm时，15 °C下生理速率的变化幅度介于0%至90%之间，30 °C下则介于0%至73%之间。对于摄食、吸收、呼吸及排泄过程，高温会强化pCO2对生理速率的影响。当暴露时长延长至31天时，pCO2仅对摄食率存在显著影响。当温度从24 °C升高至30 °C时，所有生理速率均未发生显著变化，但无论暴露时长如何，15 °C下的生理速率均显著更低。本研究数据表明，中期暴露于海洋酸化环境对秀丽织纹螺的能量代谢无显著影响。然而，在全球变暖的背景下，更长时长的暴露以及/或盐度降低可能会使该情况变得更为复杂。