National Marine Science Centre, Southern Cross University, 2 Bay Dr, Coffs Harbour, New South Wales 2450, Australia.
Fisheries Research, NSW Department of Primary Industries, National Marine Science Centre, 2 Bay Dr, Coffs Harbour, New South Wales 2450, Australia.
Sci Total Environ. 2024 Oct 1;945:174058. doi: 10.1016/j.scitotenv.2024.174058. Epub 2024 Jun 17.
Ocean warming will continue to affect the growth, body condition and geographic distributions of marine fishes and understanding these effects is an urgent challenge for fisheries research and management. Determining how temperature is recorded in fish otolith carbonate, provides an additional chronological tool to investigate thermal histories, preferences and patterns of movement throughout an individual's life history. The influence of three water temperature treatments (22°C, 25°C, and 28°C) on hatchery-reared juvenile stout whiting, Sillago robusta, was tested using a controlled outdoor mesocosm system. Fish were measured for change in length and weight, and body condition was determined using bioelectrical impedance analysis. Sagittal otoliths were analysed for stable oxygen (δO) and carbon (δC) isotopes via isotope ratio mass spectrometry. Whiting kept at 22°C were significantly smaller and had diminished body condition compared to fish in 25°C and 28°C, which did not significantly differ from each other. The δO values of stout whiting demonstrated a negative temperature-dependent fractionation relationship which was similar in slope but had a different intercept to the relationships reported for inorganic aragonite and other marine fish species. The δC values also showed a negative relationship with water temperature, and the calculated proportion of metabolic carbon M in otoliths differed between fish reared in the coolest (22°C) and warmest (28°C) temperature treatments. Overall, the results suggest that stout whiting may have reached an upper growth threshold between 25°C and 28°C, and that growth and body condition may be optimised during warmer seasons and toward the northerly regions of their distribution. Otolith oxygen thermometry shows promise as a natural tracer of thermal life history, and species-specific fractionation equations should be utilised when possible to prevent errors in temperature reconstructions of wild-caught fish.
海洋变暖将继续影响海洋鱼类的生长、身体状况和地理分布，了解这些影响是渔业研究和管理的迫切挑战。确定鱼类耳石碳酸盐中温度的记录方式，为研究个体生命历史中的热历史、偏好和运动模式提供了一种额外的时间工具。使用受控的户外中观系统测试了三种水温处理（22°C、25°C 和 28°C）对养殖幼壮拟无须鳕 Sillago robusta 的影响。测量鱼的体长和体重变化，并使用生物电阻抗分析确定身体状况。通过同位素比质谱分析矢状耳石中的稳定氧（δO）和碳（δC）同位素。与 25°C 和 28°C 相比，保持在 22°C 的拟无须鳕明显更小，身体状况也更差，而 25°C 和 28°C 之间没有明显差异。壮拟无须鳕的 δO 值表现出与温度呈负相关的分馏关系，其斜率相似，但与无机文石和其他海洋鱼类的关系的截距不同。δC 值也与水温呈负相关，在最凉爽（22°C）和最温暖（28°C）温度处理中饲养的鱼之间，耳石中代谢碳 M 的计算比例有所不同。总体而言，结果表明，壮拟无须鳕在 25°C 和 28°C 之间可能达到了生长上限，并且在温暖季节和分布区北部，生长和身体状况可能得到优化。耳石氧温测量法有望成为热生命历史的天然示踪剂，在可能的情况下，应使用特定物种的分馏方程，以防止对野生捕获鱼类的温度重建产生误差。
