PARENT SESSION
Poster Session # 17: Aquatic Systems.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Food habit divergence between two pelagic sculpin species, Comephorus baicalensis and C. dybowski in Lake Baikal.
Hitoshi, Miyasaka*,1, Yelena, Dzyuba2, Sergey, Shubenkov3, Igor, Khanayev4, Natalia, Nelnik5, Motomi, Genkai-Kato6, Eitaro, Wada7, 1 Center for Marine Environmental stadies, Ehime Univ., Matsuyama, Ehime2 Limnological Institute, Irkutsk, Irkutsk, Russia3 Limnological Institute, Irkutsk, Irkutsk, Russia4 Limnological Institute, Irkutsk, Irkutsk, Russia5 Limnological Institute, Irkutsk, Irkutsk, Russia6 Research Institute for Humanity and Nature, Kyoto, Kyoto, Japan7 Research Institute for Humanity and Nature, Kyoto, Kyoto, Japan
ABSTRACT- Stable isotope and diet composition analyses were used to show the comparisons of food habits between two species of common pelagic sculpin, Comephorus baicalensis and C. dybowski, in the northern and southern basins of Lake Baikal. The two pelagic sculpins are one of the important members for shaping the pelagic food web. Carbon and nitrogen stable isotopes could be assessed that the pelagic food web has an ideal, isotopically ordered structure in past studies. The isotopically simple structure of pelagic food web, however, has a swelling part in the middle trophic level which constructed by some pelagic sculpin species, an amphopod (Macrohectopus branickii) and a zooplankton (Epischura baicalensis). This middle part of pelagic food web was examined under the two sides, diet of two pelagic sculpins and food resource of two basins. Both nitrogen and carbon isotope data indicated that trophic positions of two pelagic sculpins differed between the species, but not between the basins. In both two basins, the delta15N value of C. baicalensis was higher than C. dybowski, because adult of C. baicalensis ate more pelagic sculpin juveniles than that of C. dybowski. In our results, we suggest that differences in diet and isotope values between the two pelagic sculpins was shown in both basins, having each different food resource environment and food choice.
Key words: stable isotope, pelagic sculpin, food habit, Lake Baikal