The Center for Applied Research On the Environment and Sustainability, The American University in Cairo, New Cairo, 11835, Cairo, Egypt.
Animal Production Department, Faculty of Agriculture, Kafrelsheikh University, Kafr El-Sheikh, 33516, Egypt.
Fish Physiol Biochem. 2023 Dec;49(6):1461-1477. doi: 10.1007/s10695-023-01267-5. Epub 2023 Nov 21.
Growing Nile tilapia in brackish water showed promising results, but the possibility of ammonia exposure can interrupt health status and productivity. Herein, the study tested the combined effects of water salinity and ammonia exposure on the antioxidative status, serum biochemistry, and immunity of Nile tilapia. Fish were assigned to eight groups where fish were reared in saline water (5, 10, and 15 ppt) with continuous or intermittent (every 3 days) total ammonia (TAN) exposure (5 mg TAN/L) (2 × 4 factorial design). After 30 days, the water salinity, TAN, and their interaction were markedly (P < 0.05), affecting the growth performance (final weight, weight gain, and specific growth rate) and survival rate of Nile tilapia. The growth performance and survival rate were markedly lower in tilapia grown in 15 ppt with continuous TAN exposure than in the remaining groups. The results showed that fish exposed to higher salinity levels (10 and 15 ppt) and continuous TAN exposure had a more robust antioxidative response, as evidenced by higher superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities and lower malondialdehyde (MDA) levels in the homogenates of the gills, intestines, and livers. The gills were notably affected, with congestion of primary filaments blood vessels and degeneration or shedding of secondary filaments epithelium, especially at salinity levels of 10 and 15 ppt. Additionally, the intestines displayed hyperplasia and inflammatory cell infiltration of intestinal mucosa at 5-10 ppt salinity, degeneration and sloughing of the intestinal epithelium at 15 ppt saline water, and increased goblet cell number at salinity of 10 ppt. The study found that continuous TAN exposure had a more significant impact on the fish, especially at higher salinity levels. Water salinity, TAN, and their interaction significantly affected all measured blood bio-indicators (total, albumin, globulin, ALT, AST, creatinine, urea, glucose, and cortisol levels). The phagocytic activity and index were markedly lowered in fish reared in 15 ppt with continuous TAN exposure, while the lysozyme activity was decreased in fish grown in 5, 10, and 15 ppt with continuous TAN exposure. In conclusion, Nile tilapia showed the possibility of growth with normal health status in brackish water (5-10 ppt); however, continuous TAN exposure can impair the productivity of tilapia, especially with high salinity (15 ppt).
在半咸水中养殖尼罗河罗非鱼显示出有前景的结果，但氨暴露的可能性会中断健康状况和生产力。在此，该研究测试了水盐度和氨暴露对尼罗河罗非鱼抗氧化状态、血清生化和免疫力的联合影响。鱼被分配到 8 组，其中鱼在盐水（5、10 和 15 ppt）中生长，并连续或间歇（每 3 天）暴露于总氨（TAN）（5 mg TAN/L）（2×4 析因设计）。30 天后，水盐度、TAN 及其相互作用显著（P<0.05），影响尼罗罗非鱼的生长性能（最终体重、体重增加和特定生长率）和存活率。在连续 TAN 暴露于 15 ppt 的尼罗罗非鱼中，生长性能和存活率明显低于其余组。结果表明，暴露于较高盐度水平（10 和 15 ppt）和连续 TAN 暴露的鱼具有更强的抗氧化反应，表现为鳃、肠和肝匀浆中的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和谷胱甘肽过氧化物酶（GPX）活性升高，丙二醛（MDA）水平降低。鳃受到显著影响，初级丝血管充血和二级丝上皮变性或脱落，特别是在盐度为 10 和 15 ppt 时。此外，在 5-10 ppt 盐度下，肠道显示出增生和肠黏膜炎性细胞浸润，在 15 ppt 盐水下，肠上皮变性和脱落，在 10 ppt 盐度下，杯状细胞数量增加。研究发现，连续 TAN 暴露对鱼类的影响更大，尤其是在较高盐度水平下。水盐度、TAN 及其相互作用显著影响所有测量的血液生物指标（总蛋白、白蛋白、球蛋白、ALT、AST、肌酐、尿素、葡萄糖和皮质醇水平）。在连续 TAN 暴露于 15 ppt 的鱼中，吞噬活性和指数显著降低，而在连续 TAN 暴露于 5、10 和 15 ppt 的鱼中，溶菌酶活性降低。总之，尼罗罗非鱼在半咸水中（5-10 ppt）生长并保持健康状态是有可能的；然而，连续 TAN 暴露会损害罗非鱼的生产力，特别是在高盐度（15 ppt）下。
