Journal of Environmental Biology

Stress responses of starry flounder, Platichthys stellatus (Pallas) following water temperature rise

Byung Hwa Min*, Mi Seon Park and Jeong-In Myeong

Division of Aquaculture Management, National Fisheries Research and Development Institute, Busan-619 705, Republic of Korea

*Corresponding Author E-mail: pkmbh@korea.kr

 Publication Data

Paper received:

13 January 2014

Revised received:

30 June 2014

Re-revised received:

13 October 2014

Accepted:

18 October 2014

Abstract

Stress responses of starry flounder, Platichthys stellatus (Pallas) following water temperature rise were investigated to establish the influence of ambient temperature on this species. The physiological indicators of stress were plasma cortisol, glucose, aspartate aminotransferase, alanine aminotransferase, sodium, chloride, osmolality and triiodothyronine (T₃). No significant difference in plasma parameters were observed among the experimental groups of 15?C, 18?C and 21?C. Level of plasma cortisol (49.0-95.0 ng ml^-1) and glucose (56.1-58.1 mg dl^-1) of starry flounders kept at 24?C-27?C were significantly higher than those (cortisol: 20.4-23.6 ng ml^-1, glucose: 40.6-47.1 mg dl^-1) observed in the 15?C-21?C groups. Changes in aspartate aminotransferase and alanine aminotransferase following water temperature rise showed a similar pattern to plasma cortisol and glucose. Starry flounders exposed to 27?C exhibited higher plasma sodium (164.7 mmol l^-1), chloride (147.6 mmol l^-1), and osmolality (450.7 mOsm kg^-1) than those (sodium: 154.0-158.7 mmol l^-1, chloride: 139.1-140.4 mmol l^-1, osmolality: 375.1-383.8 mOsm kg-1) fish exposed to 15-21?C. Though plasma T₃ (29.4 ng ml^-1) of starry flounder increased at 24?C, this hormone was significantly lower (19.3 ng ml-1) in fish kept at 27?C than those (24.6 ng ml^-1) the fish at 15?C. This phenomenon seems to be directly associated with long-term fasting. Accordingly, the results suggested that starry flounders got stressed with osmoregulatory disturbances above 24?C.   

 Key words

Platichthys stellatus, Starry flounder, Stress responses, Water temperature rise

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