舟山群岛近岸海域春秋季主要鱼类功能群特征及其生态位分析

为进一步了解舟山群岛近岸海域鱼类资源状况及其群落结构特征，基于2015年秋季（11月）、2016年春季（5月）在舟山群岛近岸海域进行的渔业资源拖网调查数据，以相对重要性指数（IRI）确定鱼类优势度，将主要鱼类（IRI>100）作为研究对象，结合其摄食习性进行功能群划分，并用Shannon指数和Pianka指数对主要鱼类的生态位进行测度。结果表明：（1）研究海域主要鱼类春季11种，秋季7种，其中优势种（IRI>1 000）春季3种，秋季1种。（2）根据食性可划分为浮游生物食性、浮游生物/游泳动物食性、底栖动物食性、底栖动物/游泳动物食性4个功能群。生物量最多的功能群春季为底栖动物食性功能群，秋季为底栖动物/游泳动物食性功能群。（3）春秋季主要鱼类生态位宽度值分别为1.26~3.58和0.20~3.45，生态位宽度值季节差异明显。广生态位种（B_i ≥2.0）春季有中华小公鱼（Stolephorus chinensis）、银鲳（Pampus argenteus）、棘头梅童鱼（Collichthys lucidus）等8种，秋季有龙头鱼（Harpodon nehereus）、凤鲚（Coilia mystus）和棘头梅童鱼3种。中生态位种（2.0 >B_i ≥1.0）春季有龙头鱼、小带鱼（Eupleurogrammus muticus）和蓝圆鲹（Decapterus maruadsi）3种，秋季有中华小沙丁鱼（Stolephorus chinensis）和鮸（Miichthys miiuy）2种，而窄生态位种（1.0>B_i >0）仅秋季的银鲳和黄鲫（Setipinna taty）2种。（4）春季龙头鱼与蓝圆鲹、秋季黄鲫与银鲳的生态位重叠值最高，表明鱼类在资源序列上的同域性最强，物种对空间资源的利用趋于一致。春秋季主要鱼类生态位重叠有意义（Q_ik >0.3）的种对所占比例均较低，总体上该海域主要鱼类潜在的竞争关系较弱，生态位空间分化明显。结合冗余分析（RDA）结果，可进一步解释主要鱼类的功能群及生态位与环境因子的相关性。

Analysis of functional groups characteristics and niche of major fish species in the coastal waters of Zhoushan Islands in spring and autumn

In order to understand the resource status and the characteristics of community structure of fish populations in the coastal waters of Zhoushan Islands, based on data of fishery resources survey in the coastal waters of Zhoushan Islands in November 2015 (autumn) and May 2016 (spring), we adopt the index of relative importance (IRI) to determine the dominance of fish species, and take the major fish species (IRI>100) as the research object. The functional groups are divided according to their feeding habits, and Shannon index and Pianka index are used to measure the niche of major fish species. The results show that: (1) There are 11 and 7 major fish species in spring and autumn respectively, among which 3 are dominant species (IRI>1 000) in spring and 1 in autumn. (2) According to their feeding habits, they can be divided into four functional groups: planktivores, planktivores/piscivores, benthivores and benthivores/piscivores. The functional group with the largest biomass is benthivores in spring and benthivores/piscivores in autumn. (3) The niche breadth of major fish species in spring and autumn are 1.26~3.58, 0.20~3.45 respectively, niche breadth differed greatly between the two seasons. The wide niche species (B_i ≥2.0) are Stolephorus chinensis, Pampus argenteus, Collichthys lucidus and 8 other species in spring, while in autumn they are Harpodon nehereus, Coilia mystus and Collichthys lucidus. The medium niche species (2.0>B_i ≥1.0) are Harpodon nehereus, Eupleurogrammus muticus and Decapterus maruadsi in spring and Stolephorus chinensis and Miichthys miiuy in autumn, and there are 2 narrow niche species (1.0>B_i >0) in autumn including Pampus argenteus and Setipinna taty. (4) The niche overlap between Harpodon nehereus and Decapterus maruadsi in spring, Setipinna taty and Pampus argenteus in autumn are the highest, indicating that the spatial homology is high and the species' use of the resources tends to be consistent. The proportion of species pairs with meaningful niche overlap (Q_ik >0.3) is low in spring and autumn, in general, the competition among major fish species is weak, niche spatial differentiation is obvious. Combining with redundancy analysis (RDA) results, we can further explain the correlation between the functional groups and niches of major fish species and environmental factors.