Journal of Environmental Biology

Temporal changes in behavioural responses and serum metabolites of Cirrhinus mrigala exposed to acute hypoxia

Paper received: 14.09.2018                    Revised received: 01.12.2018                  Re-revised received: 12.02.2019             Accepted: 13.02.2019

Authors Info

T. Varghese¹*, P. Mishal²,

G. Gupta¹, M. Kumar¹,

A.K. Pal¹ and S. Dasgupta¹

¹ICAR-Central Institute of  Fisheries Education, Mumbai-400 061, India

²ICAR-Central Inland Fisheries Research Institute, Kolkata-700 120, India

*Corresponding Author Email :

4tincy@gmail.com

Abstract

Aim: The present study was conducted to determine the tolerance to reduced oxygen level (hypoxia) and the behavioural and biochemical responses of mrigal, Cirrhinus mrigala to environmental hypoxia.   

Methodology: Cirrhinus mrigala were subjected to LC₅₀ test for 96 hr and the mortality were recorded. In a second experiment, the fishes were subjected to a stressful, but safe limit of hypoxia (0.5?0.04 mg l^-1) and the behavioral responses and serum metabolites (glucose, lactate, total lipids, free amino acids and ammonia) were evaluated for 96 hrs.   

Results: A median lethal concentration (LC₅₀, 96 hr) value of 0.25 mg l-1dissolved oxygen) was estimated for mrigal. The upper safe limit was 0.49 mg l^-1 DO and the lower lethal limit was 0.19 mg l^-1 DO. Gill ventilation frequency increased under severe hypoxic conditions and decreased with exposure time. The serum level of glucose, lactate and total lipids increased significantly (P<0.05) within 24 hr of exposure to hypoxic conditions. Free amino acids and ammonia contents were not altered by a four day exposure to hypoxia.

Interpretation: The present study explains the basic metabolic and behavioural mechanism behind the hypoxia tolerance of Indian Major Carp, mrigal assisted by alterations in gill ventilation and metabolic responses.

Key words: Behavioural responses, Cirhinus mrigala, Gill ventilation, Hypoxia, Metabolites

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