| Autor: |
Hibino S; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan., Amiya N; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan, namiya@kitasato-u.ac.jp., Miyazaki Y; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan., Nakano N; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan., Yoneda M; Hakatajima Field Station, National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries Research and Education Agency, Ehime 794-2305, Japan., Amano M; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan., Yoshinaga T; Graduate School of Marine Biosciences, Kitasato University, Kanagawa 252-0373, Japan. |
| Abstrakt: |
Western sand lance, Ammodytes japonicus , is known to have an estivation period, in which they cease feeding and stay in the sand from early summer to late autumn, followed by gonadal maturation. During the feeding period prior to estivation, they swim in daytime and spend the night in the sand. Before they start swimming, they show a typical behavior of head-exposing from the sand, which is likely to be related to foraging and predation avoidance. Our previous study revealed that melatonin regulates such diel behavior of this species. To elucidate the mechanisms of behavioral regulation throughout the life cycle of this sand lance, the present study examined the changes in behavior and melatonin secretion toward the estivation period. Both head-exposing and swimming behaviors were frequently observed at the transition period toward estivation. On the other hand, occurrence of these behaviors was suppressed just before entering estivation. Subsequently, it was found that plasma melatonin concentration was about three times higher at night than in daytime in the non-estivation period, while it was retained at high levels throughout the day in the estivation period. These results indicate that diurnal swimming behavior of sand lance from the feeding to estivation periods is associated with the daily cycle of melatonin secretion. |
