Impact of water temperature on the growth and fatty acid profiles of juvenile sea cucumber Apostichopus japonicus (Selenka)

The present study determined the changes in the fatty acid (FA) profiles of juvenile sea cucumber Apostichopus japonicus in response to the varied water temperature. Sea cucumbers with similar size (4.02 +/- 0.11 g) were cultured for 8 weeks at 14 degrees C, 18 degrees C, 22 degrees C and 26 degrees C, respectively. At the end of the experiment, the specific growth rate (SGR) and the profiles of FAs in neutral lipids and phospholipids of the juvenile sea cucumbers cultured at different temperatures were determined. The SGRs of the sea cucumbers cultured at 26 degrees C significantly decreased 46.3% compared to thos cultured at 18 degrees C. Regression analysis showed that the SGR-temperature (T) relationship can be expressed as SGR=-0.0073 T-2+0.255 T - 1.0231 (R-2=0.9936) and the highest SGR was predicted at 17.5 degrees C. For the neutral lipids, the sum of saturated FAs (SFAs), monounsaturated FAs (MUFAs) or polyunsaturated FAs (PUFAs) of the sea cucumbers that were cultured at the water temperature from 18 degrees C-26 degrees C did not change significantly, indicating the insensitivity of FA profiles for the neutral lipids of sea cucumbers in response to increasing water temperature. For phospholipids, the sum of PUFAs in the sea cucumbers dramatically decreased with the gradually increased water temperature. The sum of SFAs and MUFAs of sea cucumbers, however, increased with the gradually elevated water temperature. In particular, the contents of highly unsaturated fatty acids (HUFAs), including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA), in the phospholipids of the sea cucumbers decreased 37.2% and 26.1%, respectively, when the water temperature increased from 14 degrees C to 26 degrees C. In summary, the sea cucumbers A. japonicus can regulate the FA compositions, especially the contents of EPA and DHA, in the phospholipids so as to adapt to varied water temperature. (C) 2016 Elsevier Ltd. All rights reserved.