Udyawer Vinay, Simpfendorfer Colin A, Heupel Michelle R, Clark Timothy D
Centre for Sustainable Tropical Fisheries and Aquaculture & College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia
Australian Institute of Marine Science, Townsville, QLD 4810, Australia.
J Exp Biol. 2016 Nov 1;219(Pt 21):3447-3454. doi: 10.1242/jeb.146571. Epub 2016 Sep 2.
Cutaneous gas exchange allows some air-breathing diving ectotherms to supplement their pulmonary oxygen uptake, which may allow prolongation of dives and an increased capacity to withstand anthropogenic and natural threatening processes that increase submergence times. However, little is known of the interplay between metabolism, bimodal oxygen uptake and activity levels across thermal environments in diving ectotherms. Here, we show in two species of sea snake (spine-bellied sea snake, Hydrophis curtus; and elegant sea snake, Hydrophis elegans) that increasing temperature elevates surfacing rate, increases total oxygen consumption and decreases dive duration. The majority of dives observed in both species remained within estimated maximal aerobic limits. While cutaneous gas exchange accounted for a substantial proportion of total oxygen consumption (up to 23%), unexpectedly it was independent of water temperature and activity levels, suggesting a diffusion-limited mechanism. Our findings demonstrate that rising water temperature and a limited capability to up-regulate cutaneous oxygen uptake may compromise the proficiency with which sea snakes perform prolonged dives. This may hinder their capacity to withstand ongoing anthropogenic activities like trawl fishing, and increase their susceptibility to surface predation as their natural environments continue to warm.
皮肤气体交换使一些呼吸空气的潜水变温动物能够补充肺部的氧气摄取，这可能会延长潜水时间，并增强它们抵御人为和自然威胁过程（这些过程会增加潜水时间）的能力。然而，对于潜水变温动物在不同热环境下新陈代谢、双峰式氧气摄取和活动水平之间的相互作用，我们知之甚少。在这里，我们对两种海蛇（棘腹海蛇，Hydrophis curtus；和秀丽海蛇，Hydrophis elegans）的研究表明，温度升高会提高浮出水面的频率，增加总耗氧量，并缩短潜水持续时间。在这两种海蛇中观察到的大多数潜水都保持在估计的最大有氧极限范围内。虽然皮肤气体交换占总耗氧量的很大比例（高达23%），但出乎意料的是，它与水温及活动水平无关，这表明存在一种扩散限制机制。我们的研究结果表明，水温上升以及上调皮肤氧气摄取的能力有限，可能会损害海蛇进行长时间潜水的能力。这可能会阻碍它们抵御拖网捕鱼等持续人为活动的能力，并随着它们的自然环境持续变暖，增加它们遭受水面捕食的易感性。
