Laboratory of Fish Ecophysiology, Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.
J Therm Biol. 2020 Oct;93:102738. doi: 10.1016/j.jtherbio.2020.102738. Epub 2020 Sep 23.
Increase in water temperature due to anthropogenic and climatic changes is expected to affect physiological functions of fish. In this study, we determined high temperature tolerance (CTmax) of a common aquacultured Indian major carp, rohu, Labeo rohita fingerlings (15.96 ± 0.72 g BW, 11.56 ± 0.42 cm TL) followed by acclimatization at three temperatures (30, 33, 36 °C). To determine the CTmax, we analyzed the major hemato-biochemical indices - hemoglobin (Hb), red blood cell (RBC), white blood cell (WBC), blood glucose levels, and erythrocytic nuclear abnormalities (ENAs) and erythrocytic cellular abnormalities (ECAs) of peripheral erythrocytes in the fish sampled at the start and end point at each acclimated temperature. Significantly decreased CTmax of the fish was found at 36 °C compared to 30 °C and 33 °C. The fish in the highest (36 °C) temperature were found with significantly lower Hb and RBC content and significantly higher WBC and blood glucose levels than that of the fishes in the lowest (30 °C) temperature both at the start and end points. The highest frequencies of ENAs and ECAs were found in the highest (36 °C) temperature group compared to the lowest (30 °C) temperature group at both the points. We also evaluated growth performance of the rohu fingerlings reared in the three temperatures for 60 days. The growth parameters - final weight gain, percent weight gain and specific growth rate were the highest at 33 °C and the lowest at 36 °C. The present study revealed that the highest temperature (36 °C) tested here may be hazardous to rohu and the temperature should be kept below 36 °C in the aquaculture setting to avoid physiological damage and growth and production loss to the fish.
由于人为和气候变化导致的水温升高预计会影响鱼类的生理功能。在这项研究中，我们测定了养殖的印度鲤鱼（Labeo rohita）幼鱼（15.96±0.72g BW，11.56±0.42cm TL）的高温耐受能力（CTmax），随后在三个温度（30、33、36°C）下进行驯化。为了确定 CTmax，我们分析了主要的血液生化指标——血红蛋白（Hb）、红细胞（RBC）、白细胞（WBC）、血糖水平以及外周红细胞的红细胞核异常（ENAs）和红细胞细胞异常（ECAs）。在每个驯化温度下的起点和终点采集鱼类样本进行分析。结果发现，与 30°C 和 33°C 相比，36°C 时鱼类的 CTmax 显著降低。在最高温度（36°C）下的鱼类与在最低温度（30°C）下的鱼类相比，Hb 和 RBC 含量显著降低，WBC 和血糖水平显著升高，无论在起点还是终点都是如此。与最低温度（30°C）组相比，在两个时间点，最高温度（36°C）组的 ENAs 和 ECAs 频率都显著更高。我们还评估了在这三个温度下养殖的鲤鱼幼鱼 60 天的生长性能。在 33°C 时，最终体重增加、体重百分比增加和特定生长率等生长参数最高，而在 36°C 时最低。本研究表明，我们这里测试的最高温度（36°C）可能对罗非鱼有害，在水产养殖中应将水温保持在 36°C 以下，以避免对鱼类造成生理损伤和生长及生产损失。
