Study on Trophic Niches of Sebastes schlegelii and Hexagrammos otakii in the artificial reef area of Xiaoheishan Island

This study analyzed the niche overlap and wide variation between two typical reef fish species, Sebastes schlegelii and Hexagrammos otakii, from an artificial reef area of Xiaoheishan Island, during spring and autumn. The δ13C value of S. schlegelii was significantly higher than that of H. otakii in spring, while there was no difference between the two species in autumn. Moreover, the δ15N value of S. schlegelii was significantly greater than that of H. otakii in both spring and autumn. The frequency distribution of S. schlegelii δ13C values was always greater than that of H. otakii, while the seasonal variation of the δ15N frequency distribution was less than that of H. otakii. We concluded that S. schlegelii utilized a wide range of food sources and occupied a stable trophic level, while H. otakii had a narrower preference for food, and the trophic level it occupied fluctuates dramatically. In addition, there was an overlap of trophic niches between the two species only in autumn, while at other times S. schlegelii had a higher and wider trophic niche than H. otakii. In conclusion, we found there was interspecific competition between S. schlegelii and H. otakii in the artificial reef community, and S. schlegelii had a superior ability to utilize food resources.