长江口拟长脚数量变化和对环境变暖的响应

据1959年和2002年在长江口29°00′～32°00′ N, 122°00′～123°30′ E海域四季调查资料,研究结合拟长脚丰度和同步水温资料进行曲线拟合、构造数学模型和计算最适温度.分析拟长脚(Parathemisto gaudichaudi)的生态类型、空间分布、数量动态以及对变暖趋势的响应.结果表明:长江口海域拟长脚平均丰度和出现率都表现为夏秋季较低和冬春季较高.1959年春季平均丰度最高,为1.8 ind/m3；1959年秋季平均丰度最低,为0.03 ind/m3.1959年春季出现率最高,为62.96%；1959年秋季出现率最低,为6.90%.长江口拟长脚在1959年春季丛生指标最大(7.12),在1959年秋季最小(-1.00).这说明该种春季在长江口海域有明显的集群性,秋季集群性则不明显.温度是影响拟长脚季节变化和年间变化的主要因素.长江口海域拟长脚丰度和同步温度资料曲线拟合结果符合Yield Density模型,最适温度是17.0 ℃,置信度分析和拟合统计结果均有非常高的置信度.综合拟长脚最适温度和季节变化特征,可认为该种是暖温种.近年来在春季长江口水域的拟长脚丰度有所降低,这种数量年间变化趋势应与全球气候变暖相关.该种可作为海洋变暖长期变化的指示种.

Effect of global warming on abundance variation of Parathemisto gaudichardi (Amphipoda) in the Changjiang Estuary

The spatial and abundance patterns of Parathemisto gaudichaudi (Amphipoda) were investigated in the Changjiang Estuary (29°00′-32°00′N, 122°00′-123°30′E) between 1959 and 2002. The species′ ecological group was classified and its optimal temperature calculated through the analysis of concurrent abundance and environmental data collected during the cruises and application of a mathematical model. Relationships between abundance variation between years and global warming were then analyzed for the Changjiang Estuary. The results revealed a distinguished seasonal change in both abundance and frequency of occurrence for Parathemisto gaudichaudi in the Estuary; both were higher in spring and winter than in summer or autumn. Average abundance in 1959 was highest in spring and lowest in autumn (1.8 ind/m~3 and 0.03 ind/m~3, respectively). Frequency of occurrence was highest (62.96%) in spring and lowest (6.90%) in autumn. The clumping index for Parathemisto gaudichaudi in the Changjiang Estuary was higher in spring (7.1) than in autumn (-1.0) in 1959, which indicated that the species showed clear aggregation in spring. The optimal temperature for Parathemisto gaudichaudi in the Changjiang Estuary was about 17 ℃, as calculated from the Yield Density model (P=0.0001). Based on its optimal temperature and seasonal abundance variation, Parathemisto gaudichaudi could be classified as a temperate water species. The spring abundance of Parathemisto gaudichaudi had clearly decreased between 1959 and 2002 and the decline may be related to global warming in the Changjiang Estuary. Parathemisto gaudichaudi could be regarded as an important indictor species for global warming in the area.