北黄海獐子岛海域浮游植物沉降通量的周年变化

Annual variations in the phytoplankton settling flux in the northern Yellow Sea off Zhangzi Island

中文关键词: 浮游植物  沉降通量  周年变化  獐子岛  虾夷扇贝

英文关键词: Phytoplankton  Settling flux  Annual variation  Zhangzi Island  Patinopecten yessoensis

中文摘要:

      于2011年9月至2012年11月，在北黄海獐子岛邻近海域，利用德国MST24型沉积物捕集器，开展了5 d期采样频率的浮游植物组成及其沉降通量的周年变化研究。71份沉降样品共记录浮游植物51属93种，其中硅藻38属66种，是主要的沉降类群。沉降优势种主要有具槽帕拉藻(Paralia sulcata)、离心列海链藻(Thalassiosira excentrica)、布氏双尾藻(Ditylum brightwellii)、辐射圆筛藻(Coscinodiscus radiatus)、八幅辐环藻(Actinocyclus octonarius)等硅藻物种，以及小等刺硅鞭藻(Dictyocha fibula)、八幅硅鞭藻(Octactis octonaria)等硅鞭藻物种。浮游植物沉降通量变化在(6.1~169)×106 cells/m2d，平均39.4×106 cells/m2d，在春、秋季各出现1个高通量时段，春季峰值主要为硅藻贡献，而秋季峰值则由硅藻和硅鞭藻共同形成。沉降浮游植物作为獐子岛底播虾夷扇贝的重要饵料，其种类组成及沉降通量的周年变化，与獐子岛海域虾夷扇贝的底播、生长时节相关，以具槽帕拉藻、海链藻、圆筛藻等硅藻属种为主的食物来源和结构是扇贝重要的饵料基础。旨在通过浮游植物沉降的时间序列研究，查明獐子岛底播虾夷扇贝的饵料组成及其通量水平的周年变化特征，为该水域可持续的底播养殖提供基础资料和参考依据。

英文摘要:

      In recent years, global warming and the release of hot wastewater from nuclear power plants have caused the temperature of sea water to rise, leading to severe thermal pollution of the oceans. Marine ecosystems and the survival of marine life face huge challenges from ocean warming. Research on the thermal tolerance of marine organisms will help us to understand the heat tolerance of different marine species and determine how to control thermal discharge from nuclear power plants. This study investigated the heat tolerance of four marine species (Chaeturichthys stigmatias, Sebastes schlegeli, Oratosquilla oratoria, and Charybdis japonica) in Liaodong Bay using a dynamic temperature-rising test. The lethal temperature of 50% (LT50) was assessed at five acclimation temperatures (8.0℃, 14.0℃, 18.0℃, 24.0℃, 28.0℃) and nine temperature-rising rates (0.5, 1.0, 2.0, 3.0, 4.0, 6.0, 9.0, 12.0, 15.0℃/h) to evaluate heat tolerance. The results showed that both the acclimation temperature and temperature-rising rate significantly affected the LT50 value of the experimental animals (P<0.05). The LT50 values were significantly positively correlated with the acclimation temperature (P<0.05), while the effects of the temperature-rising rate varied with acclimation temperature in a species-dependent manner. In this study, the dynamic temperature-rising test included a higher number of acclimation temperatures and temperature-rising rates than used in previous studies, and we established the LT50 value as an important indicator for evaluating the heat tolerance of marine species. These results suggest that as an evaluated index, LT50 comprehensively reflects the heat tolerance of experimental species, which is of scientific and ecological significance and could be widely used in the assessment of heat tolerance.