舟山长白海域主要游泳动物生态位及其分化研究

基于2016年10月（秋季）和2017年4月（春季）舟山长白海域的渔业资源调查数据，运用生态位宽度、生态位重叠及冗余分析等方法，研究了主要游泳动物的生态位，种间生态关系及生态位分化。结果显示：春、秋季主要游泳动物分别11种与8种，两季生态位宽度值差异均较大，其中春季广生态位种、中生态位种均为3种，而秋季均为2种，窄生态位种分别为5种与4种。相对重要性指数（IRI）与生态位宽度值（B_i）之间呈显著正相关。生态位重叠程度不均衡，秋季主要游泳动物的生态位重叠程度较高，O_ik > 0.6的种对数占总种对数的42.86%；春季的重叠程度较低，仅占总种对数的21.82%。RDA分析得出温度、盐度为影响主要游泳动物分布的直接因素，而溶解氧、悬浮物和pH等则为重要因素，主要游泳动物在这些资源维上存在生态分化现象。综上，分布在毗邻杭州湾口且位于著名的岱衢洋的主要游泳动物种类总体营养级较低却生态宽度值较大，大黄鱼（Larimichthys crocea）、黄姑鱼（Nibea albiflora）等一些传统的高营养级、典型特色经济种类却沦为生态位宽度极小的一般种或少有种，群落种类显著减少，资源量下降，群落结构与功能退化，稳定性下降。因此，加强游泳动物资源修复、保护与管理十分迫切且具有重要意义。

Study on the niche and differentiation of major nekton species in the Zhoushan Changbai sea area

Based on the data of the fisheries resources survey in the Zhoushan Changbai sea area in October 2016 (autumn) and April 2017 (spring), the ecological niche, interspecific ecological relationship, and ecological niche differentiation of the major nekton species were studied using the methods of niche breadth, niche overlap, and redundancy analysis (RDA). The results showed the presence of 11 and 8 major nekton species in spring and autumn, respectively, with large differences between the niche breadth values obtained in the two seasons. It is observed that there are three kinds of both wild ecological species and middle niche species in spring, and two in autumn, with five and four narrow niche species in spring and autumn, respectively. A significant positive correlation existed between the index of relative importance (IRI) and niche breadth value (Bi). The degree of niche overlap of the major nekton species was unbalanced, being relatively high in autumn, with the species pairs of O_ik > 0.6 accounting for 42.86% of the total niche overlap. The degree of niche overlap of the major nekton species was relatively low in spring, accounting for only 21.82% of the total niche overlap. The RDA showed that temperature and salinity were the factors directly affecting the distribution of the major nekton species, while dissolved oxygen, suspended matter, and pH were also important factors. The major nekton species showed ecological differentiation in these resource dimensions. In summary, the major nekton species that were distributed in the waters of Daiquyang and the area adjacent to the mouth of Hangzhou Bay showed an overall low trophic level, but had a large niche breadth. Some of the traditional high-trophic level and typical economic species were replaced with the general or rare species of narrow niche breadth, for example, Larimichthys crocea and Nibea albiflora, etc. A significant reduction was observed in their community species, resources, stability along with the degradation of community structure and function. Therefore, it is of great significance and urgent to strengthen the monitoring, protection, and management of nekton in the Zhoushan Changbai sea area.