Serum cortisol level and survival rate of juvenile Epinephelus fuscoguttatus following exposure to different salinities

Vet World Vol.11 March-2018 Article-12

Research Article

Veterinary World, 11(3): 327-331

https://doi.org/10.14202/vetworld.2018.327-331

Diyana Tahir¹, M. Shariff^1,2, Fadhil Syukri^1,3, and F. M. Yusoff^1,3

1. Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, Malaysia.
2. Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Malaysia.
3. Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, Malaysia.

Background and Aim: Brown-marbled grouper Epinephelus fuscoguttatus is a premium marine food fish with high demand in Asia. In fish, stress due to environmental changes such as fluctuations in the salinity can result in increased cortisol level. Stress in fish increases susceptibility to diseases ultimately resulting in death. Therefore, the aim of this study was to investigate the salinity tolerance of E. fuscoguttatus and their survival in lower salinities.

Materials and Methods: In this study, grouper juveniles (92.43±standard error of the mean 0.51 mm) maintained in 31 ppt seawater were transferred into five tanks with seawater diluted to 25, 20, 15, 10, and 5 ppt. The salinity of the control group was not changed and was maintained at 31 ppt. Serum cortisol was measured using ELISA at 0, 30, 60, and 120 min after the fish were transferred to the different concentrations of salinity.

Results: The survival percentage was recorded for 14 days following the transfer and the results revealed that serum cortisol of fish in a high change in salinity (15, 10, and 5 ppt) was significantly higher than the control group immediately after exposure. At the high salinity change, the cortisol levels gradually decrease at 30 min and 60 min, until no difference in cortisol concentration was observed at 120 min. No mortality was observed in fish exposed to low salinity change (25 and 20 ppt) while in higher salinity change (5 ppt), the survival percentage was 50%.

Conclusion: The study revealed that the serum cortisol concentration was high initially and continues to decrease to resting cortisol level at 120 min indicating that cortisol hormone is released following acute stress as a primary response in grouper juveniles. Keywords: cortisol, Epinephelus fuscoguttatus, salinity, serum, stress, survival.

Keywords: cortisol, Epinephelus fuscoguttatus, salinity, serum, stress, survival.

How to cite this article: Tahir D, Shariff M, Syukri F, Yusoff FM (2018) Serum cortisol level and survival rate of juvenile Epinephelus fuscoguttatus following exposure to different salinities, Veterinary World, 11(3): 327-331.

Received: 03-11-2017 Accepted: 14-02-2018 Published online: 17-03-2018

Corresponding author: M. Shariff E-mail: pshariff@gmail.com

DOI: 10.14202/vetworld.2018.327-331

Copyright: Tahir, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.