Carey Nicholas, Harianto Januar, Byrne Maria
Schools of Medical and Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia Hopkins Marine Station, Stanford University, 120 Ocean View Boulevard, Pacific Grove, CA 93950, USA
Schools of Medical and Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.
J Exp Biol. 2016 Apr 15;219(Pt 8):1178-86. doi: 10.1242/jeb.136101. Epub 2016 Feb 19.
Body size and temperature are the major factors explaining metabolic rate, and the additional factor of pH is a major driver at the biochemical level. These three factors have frequently been found to interact, complicating the formulation of broad models predicting metabolic rates and hence ecological functioning. In this first study of the effects of warming and ocean acidification, and their potential interaction, on metabolic rate across a broad range in body size (two to three orders of magnitude difference in body mass), we addressed the impact of climate change on the sea urchin ITALIC! Heliocidaris erythrogrammain context with climate projections for southeast Australia, an ocean warming hotspot. Urchins were gradually introduced to two temperatures (18 and 23°C) and two pH levels (7.5 and 8.0), at which they were maintained for 2 months. Identical experimental trials separated by several weeks validated the fact that a new physiological steady state had been reached, otherwise known as acclimation. The relationship between body size, temperature and acidification on the metabolic rate of ITALIC! H. erythrogrammawas strikingly stable. Both stressors caused increases in metabolic rate: 20% for temperature and 19% for pH. Combined effects were additive: a 44% increase in metabolism. Body size had a highly stable relationship with metabolic rate regardless of temperature or pH. None of these diverse drivers of metabolism interacted or modulated the effects of the others, highlighting the partitioned nature of how each influences metabolic rate, and the importance of achieving a full acclimation state. Despite these increases in energetic demand there was very limited capacity for compensatory modulating of feeding rate; food consumption increased only in the very smallest specimens, and only in response to temperature, and not pH. Our data show that warming, acidification and body size all substantially affect metabolism and are highly consistent and partitioned in their effects, and for ITALIC! H. erythrogramma, near-future climate change will incur a substantial energetic cost.
体型和温度是解释代谢率的主要因素，而pH值这一额外因素是生化水平上的主要驱动因素。人们经常发现这三个因素相互作用，使得预测代谢率进而预测生态功能的广义模型的构建变得复杂。在这项关于变暖和海洋酸化及其潜在相互作用对广泛体型范围（体重相差两到三个数量级）内代谢率影响的首次研究中，我们结合澳大利亚东南部这一海洋变暖热点地区的气候预测，探讨了气候变化对海胆红斑疣海胆（Heliocidaris erythrogramma）的影响。海胆被逐步引入到两个温度（18和23°C）和两个pH水平（7.5和8.0）下，并在这些条件下维持2个月。相隔数周进行的相同实验验证了已达到新的生理稳态这一事实，也就是所谓的驯化。体型、温度和酸化对红斑疣海胆代谢率的关系非常稳定。两种应激源都会导致代谢率增加：温度升高20%，pH值升高19%。综合效应是相加的：代谢增加44%。无论温度或pH值如何，体型与代谢率都有高度稳定的关系。这些不同的代谢驱动因素之间没有相互作用或调节其他因素的影响，突出了每种因素影响代谢率的独立性，以及达到完全驯化状态的重要性。尽管能量需求增加，但摄食率的补偿调节能力非常有限；仅在最小的个体中食物消耗增加，且仅对温度有反应，对pH值无反应。我们的数据表明，变暖和酸化以及体型都对代谢有显著影响，且它们的影响高度一致且相互独立，对于红斑疣海胆来说，近期的气候变化将带来巨大的能量成本。
