Acidified seawater suppresses insulin-like growth factor I mRNA expression and reduces growth rate of juvenile orange-spotted groupers, Epinephelus coioides (Hamilton, 1822)

Ocean acidification, resulted from high level of carbon dioxide (CO2) dissolved in seawater, may disturb the physiology of fish in many ways. However, it is unclear how acidification may impact the growth rate and/or growth hormones of marine fish. In this study, we exposed juvenile orange-spotted groupers (Epinephelus coioides) to seawater of different levels of acidification: a condition predicted by the Intergovernmental Panel on Climate Change (pH 7.8–8.0), and a more extreme condition (pH 7.4–7.6) that may occur in coastal waters in the near future. After 6 weeks of exposure, the growth rates of fish in pH 7.4–7.6 were less than those raised in control water (pH 8.1–8.3). Furthermore, exposure at pH 7.4–7.6 increased blood pCO2 and HCO3− significantly; exposure at pH 7.8–8.0, meanwhile, did not affect acid–base chemistry. Moreover, exposure to pH 7.4–7.6 resulted in lower levels of hepatic igf1 (insulin-like growth factor I) mRNA, but did not affect levels of pituitary gh (growth hormone) or hypothalamus psst2 and psst3 (prepro-somatostatin II and III). The results show that highly acidified seawater suppresses growth of juvenile grouper, which may be a consequence of reduced levels of IGF-1, but not due to diminished growth hormone release.

Shao Y. T., Chang F. Y., Fu W.-C. & Yan H. Y., 2016. Acidified seawater suppresses insulin-like growth factor I mRNA expression and reduces growth rate of juvenile orange-spotted groupers, Epinephelus coioides (Hamilton, 1822). Aquaculture Research 47(3):721–731. Article (subscription required).


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