不同溫度環境下維氏腦紋珊瑚的有性生殖

Abstract

Coral reefs worldwide suffer from increasing anthropogenic and climatic disturbances. Response of corals with different life-histories strategies may provide valuable insights on which species may occur in future communities. Particularly, reproduction is usually considered as a key factor for the maintenance of coral population. In this study, we compare the reproduction of corals in two contrasting thermal environments: Wanlitung, and the Outlet of the Nuclear Power Plant (NPP Outlet), located at Kenting - Southern Taiwan. Fifteen colonies of massive coral Platygyra verweyi was tagged respectively at each site. Colonies were sampled from March 2012 to May 2013 and their histological statements were examined. Temperature recorder showed average temperature and daily temperature variation at NPP Outlet (27.9 ± 1.5 °C, 2.1 ± 1.0 °C, respectively ) were higher than Wanlitung (27.1 ± 1.6 °C, 1.1 ± 0.4 °C, respectively, Paired t-test, p <0.001). Results confirmed that P. verweyi is simultaneous hermaphrodite with a single annual reproductive cycle at both sites. However, mature egg diameter of P. verweyi at the Outlet (270 ± 34 μm, n = 300) was larger than at Wanlitung (225 ± 31 μm, n = 300). Number of matured eggs in P. verweyi was lower in samples from Outlet (72 ± 32 polyp-1, n = 45) compared to Wanlitung (137 ± 61 polyp-1, n = 45). No linear regression relationship was found between colony size and egg size or number between two sites. Overall, this study shows that reproductive responses in corals inhabited in the contrast environments implicated differ remarkably. The change in reproduction represents that P. verweyi may have alternative reproductive strategies for egg size, fecundity, and gamete development at the NPP Outlet and Wanlitung, due to adaptation or acclimatization of life history characteristics in different thermal environments.