Wade Nicholas M, Clark Timothy D, Maynard Ben T, Atherton Stuart, Wilkinson Ryan J, Smullen Richard P, Taylor Richard S
CSIRO Agriculture and Food, Queensland Biosciences Precinct, St Lucia, QLD 4067, Australia.
CSIRO Agriculture and Food, Castray Esplanade, Hobart, TAS 7000, Australia; Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001, Australia.
J Therm Biol. 2019 Feb;80:64-74. doi: 10.1016/j.jtherbio.2018.12.021. Epub 2018 Dec 27.
Global seawater temperatures are increasing and becoming more variable, with consequences for all marine animals including those in food production systems. In several countries around the world,arming of Atlantic salmon (Salmo salar) occurs towards the upper end of the thermal tolerance window for this species, and marked effects on salmon production during summers have been experienced but never empirically investigated. This project tracked the effects of an extreme summer heatwave on two different cohorts of fish stocked into farm cages either during early winter (EW) or late winter (LW). The farm site experienced an unprecedented high water temperature event, with a peak water temperature of 22.9 °C and 117 days above 18 °C. Fish in both EW and LW cohorts experienced a temperature-induced cessation of voluntary feed intake as well as inefficient osmoregulatory, liver and renal function during high temperature periods. Flesh colour declined primarily in the dorsal and ventral regions of the fillet and secondarily along the midline, with over 20% of fish demonstrated a complete loss of flesh colour during the months of March and April. A return to feeding in autumn occurred faster in some fish and caused a marked bimodal size distribution to appear within both the EW and LW cohorts as autumn progressed. However, the LW cohort returned to feeding at seawater temperatures of 20.2 °C, compared with 18.6 °C for the EW cohort. There was a strong positive relationship between fillet colour recovery and residual condition index (RCI). These findings identified alkaline phosphatase as a potential marker to non-destructively track individual fish for signs of recovery after a thermal stress event, and shed light on the physiological consequences of marine heatwaves on fishes. This study also identified that supporting feed intake or promoting a return to feeding may help mitigate the negative impacts of climate warming on cultured Atlantic salmon.
全球海水温度正在上升且变化愈发无常，这对所有海洋动物都产生了影响，包括那些处于水产养殖系统中的动物。在世界上的几个国家，养殖的大西洋鲑（Salmo salar）正处于该物种热耐受窗口的上限，夏季对鲑鱼产量产生了显著影响，但从未经过实证研究。本项目追踪了一场极端夏季热浪对两个不同批次养殖在网箱中的鱼类的影响，这两个批次的鱼分别在初冬（EW）或晚冬（LW）投放。养殖场经历了一场前所未有的高温事件，水温峰值达到22.9°C，且有117天水温高于18°C。EW和LW批次的鱼在高温期都经历了因温度导致的自愿摄食停止，以及渗透调节、肝脏和肾脏功能效率低下的情况。鱼肉颜色主要在鱼片的背部和腹部区域下降，其次是沿着中线下降，在3月和4月期间，超过20%的鱼出现了完全褪色。随着秋季的推进，一些鱼秋季恢复摄食的速度更快，导致EW和LW批次的鱼体内都出现了明显的双峰大小分布。然而，LW批次的鱼在海水温度为20.2°C时恢复摄食，而EW批次的鱼则是在18.6°C时恢复摄食。鱼片颜色恢复与剩余状况指数（RCI）之间存在很强的正相关关系。这些发现确定碱性磷酸酶是一个潜在的标志物，可用于无损追踪个体鱼类在热应激事件后的恢复迹象，并揭示了海洋热浪对鱼类的生理影响。本研究还确定，支持摄食或促进恢复摄食可能有助于减轻气候变暖对养殖大西洋鲑的负面影响。
