闽东近海游泳动物群落组成、资源量与生物多样性的时空格局研究

THE TEMPO-SPATIAL CHANGES IN COMMUNITY STRUCTURE, BIOMASS, AND BIODIVERSITY OF NEKTON IN THE EASTERN COASTAL WATERS OF FUJIAN PROVINCE

采用底拖网方法调查研究了闽东近海春季(5月)和秋季(10月)游泳动物群落组成、生物多样性、资源密度及时空分布格局等问题。调查中出现游泳动物70种(鱼类47种,甲壳类18种,头足类5种),隶属于15目40科64属,以鲈形目种类最多(25种)。鱼类是主要游泳动物群落,春季鱼类个体数和重量分别占总渔获的66.4%和72.3%,甲壳类分别占比33.4%和26.9%,头足类分别占比0.2%和0.8%;秋季,上述三个类群在总渔获中的占比分别为56.6%和60.4%、42.0%和37.8%以及1.4%和1.8%。春季优势种包括红狼牙虎鱼(Odontamblyopus rubicundus)、三疣梭子蟹(Portunus trituberculatus)、孔虎鱼(Trypauchen vagina)等10种,秋季优势种为龙头鱼(Harpadon nehereus)、三疣梭子蟹、六指马鲅(Polynemus sextarius)等7种;两个季节共有优势种包括三疣梭子蟹、日本 (Charybdis japonica)、龙头鱼、棘头梅童鱼(Collichthys lucidus)和六丝钝尾虎鱼(Amblychaeturichthys hexanema)5种。秋季的生物多样性指数和均匀度指数高于春季。春季平均资源密度为1013.7kg/km^2和10.2×10^4ind/km^2,高于秋季的平均值(899.0kg/km^2和6.6×10^4ind/km^2)。总体而言,鱼类是闽东近海主要的游泳动物类群,其资源密度从近岸向外海呈降低趋势,春季的资源密度高值出现在闽东外海中部水域,秋季高值则出现在南部的闽江口等水域;其春季的优势种种类多于秋季,存在一定程度季节性更替现象。

Two fishery surveys were conducted to investigate the community structure, biodiversity, and biomass of the nekton in the eastern coastal waters of Fujian Province in May and October, 2017. A total of 70 species(47 fish, 18 crustaceans, and 5 cephalopods) were found in this region. Perciformes fish accounted for the largest number of species(25), followed by Stomatopoda(18), and Clupeiformes(7). Fish dominated the total catches both in individuals(66.4%) and in weight(72.3%) in the spring survey, whereas it accounted for 56.6% and 60.4% of the catches, respectively, in the autumn survey. Crustacean, both in the individuals and in weight, accounted for 33.36% and 26.87% of the total catches in spring, compared to 42.02% and 37.79% in autumn, respectively. Cephalopods only accounted for a minor part of the catches. Dominant species varied between the two seasons, with 10 species(Odontamblyopus rubicundus, Portunus trituberculatus, Trypauchen vagina, etc.) in May and seven species(Harpadon nehereus P. trituberculatus, Polynemus sextarius, etc.) in October. Mean values of the biodiversity index(H′, 2.75 and 2.96 estimated by individuals and weight of the catches, respectively) and the evenness index(J′, 0.67 and 0.72) of the nekton community in the survey area in autumn were higher than those(H′, 2.69 and 2.76;J′, 0.67 and 0.69) in spring. Mean biomass density of the nekton(10.2×104 ind/km2) in May was higher than that in October(6.6×104 ind/km2), whereas those by catch weight were on the same level in May(1013.7 kg/km2) and in October(899.0 kg/km2). Overall, the biomass density of the nekton tended to decrease from the near-shore waters to the offshore waters, peaking in the central survey areas in May but in the southern survey areas in October. Seasonal replacement of dominant species occurred between spring(10 species in May) and autumn(7 species in October), in which five species were in common.