Immunological, hematological, and histological responses in blood, spleen and gill of Salmo caspius juveniles exposed in different water temperatures

Document Type : Research Paper

Authors

1 Department of Fisheries, Bandar abbas Branch, Islamic Azad University, Bandar abbas, Iran

2 lahijan

3 Inland Water Aquaculture Center, Iranian Fisheries Sciences Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Bandar Anzali, Iran, P. O. Box: 61

Abstract

Caspian brown trout, Salmo caspius, were subject to five temperatures (5°C, 8°C, 20°C, 25°C, and 28°C) for two durations 12 and 24 hours. The fish were maintained for 48 hours at a water temperature of 9-10°C to acclimatize.The water temperature was changed gradually at a rate of 2°C per hour to the respective temperatures. Exposure to temperatures of 25 and 28°C resulted in loss of all fish. Red blood cell, hemoglobin concentration, and hematocrit were decreased at 5°C compared to control (8°C) and 20°C in duration of 12h. Temperature tension did not affect the mean cell volume and mean cell hemoglobin value during the 12 and 24h duration (p >0.05). Neutrophils percentage was  significantly higher at 5°C and 20°C, but the most percentage of lymphocytes was noted in the control group. Cortisol, glucose, and lactate values elevated in both periods when water temperature decreased to 5°C compare to the control and 20°C groups (p <0.05). The levels of albumin and total protein in the duration of 12h at 20°C were significantly higher than control and 5°C, but this trend was not seen in the exposure of 24h (p <0.05). The lysozyme activity and immunoglobin M were affected by varying temperatures (p <0.05), and highest levels were observed in control groups.  Most histopathological changes in gill, such as epithelial hypertrophy, curling of lamella, and necrosis of the epithelial cell were observed at 20°C; whereasthese were less affected at 5°C and 8°C.  Lowest hemorrhages in the spleen and lowest size of sinusoids were observed in 8°C and 5°C treatments respectively. Overall, temperature variation had a superior impact on gills than spleen. Taken together, the results of the present study showed that sudden variation beyond the optimum temperature leads to physiological and pathological changes.

Keywords

Iranian Journal of Fisheries Sciences
Volume 19, Issue 6
November 2020

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