Abstract:

In order to investigate the population dynamic of the ichthyoplankton and its relationship with environmental factors, five surveys were conducted along coastal waters of the southern Shandong Peninsula from April to July, 2017. A total of 5042 fish eggs and 108 larvae were collected during the five surveys by horizontal trawl with plankton net. The obtained ichthyoplanktons belonged to 24 species, 24 genera, 18 families, and 7 orders. The dominant species of fish eggs were Engraulis japonicus and Konosirus punctatus. As referred to fish larvae, Amblychaeturichthys hexanema and Engraulis japonicus were the key species, whereas no dominant species appeared. The species of the ichthyoplanktons with high index of relative importance (IRI) varied obviously among seasons. The adult fish corresponding to the ichthyoplanktons had an average trophic level of 3.41,belonging to low-grade carnivorous fish in the third trophic level. The nutritional structure of adult fish corresponding to the ichthyoplanktons collected in spring and summer was similar. Due to the overfishing and environmental degradation, the trophic level of the fish in the Yellow Sea has been decreasing year by year. The GAM model showed that the optimum temperature for the ichthyoplankton was 16?20 ℃. The quantity distribution of the ichthyoplanktons first decreased and then increased slowly with the increase of the water depth. The optimum salinity for the ichthyoplanktons was 31.5?32. Month, latitude, and depth had significant effects on the distribution of the ichthyoplankton (P<0.01 or P<0.05). The cluster analysis revealed that the ichthyoplanktons collected in spring and summer were divided into three station groups. The differences in station grouping were observed among seasons. In spring, the main divergent species between the two nearshore groups were Konosirus punctatus, Cynoglossus joyneri, Nibea albiflora, and Sillago sihama. In summer, the main divergent species between nearshore group and offshore group were Konosirus punctatus, Engraulis japonicus, and Cynoglossus joyneri, which were mostly found in nearshore group. Then, the relationship between the spatial pattern of the ichthyoplankton community structure and environmental factors in the studied area were obtained. These results provided technical support for scientific understanding, protection, and management of fishery resources along coastal waters of southern Shandong Peninsula.

Key words: fish eggs, fish larvae, species composition, trophic level, GAM model, community structure

摘要：

为了解鱼卵、仔稚鱼的种群动态及其与环境因子之间的关系,2017年4—7月,利用大型浮游生物网对山东半岛南部近岸海域进行水平拖网调查。5个航次调查共采集鱼卵5042粒,仔稚鱼108尾,共24个物种,隶属于7目18科24属。鱼卵的优势种为鳀（Engraulis japonicus）和斑鰶（Konosirus punctatus）,仔稚鱼没有出现优势种,六丝钝尾虾虎鱼（Amblychaeturichthys hexanema）和鳀构成仔稚鱼的重要种。鱼卵、仔稚鱼的最高优势度物种之间的季节更替明显。鱼卵、仔稚鱼对应的成鱼平均营养级为3.41,处于第三营养级低级肉食性鱼类范畴;春季和夏季采集的鱼卵、仔稚鱼对应的成鱼营养结构相似。利用GAM模型研究了山东半岛南部近岸海域鱼卵、仔稚鱼分布与环境因子的关系。结果显示,鱼卵、仔稚鱼的最适温度在16—20 ℃之间。水深对数量分布的影响总体呈先下降后缓慢升高的趋势;盐度31.5—32为鱼卵、仔稚鱼的最适盐度。月份、纬度和深度等因子对鱼卵、仔稚鱼的分布均有显著影响（P<0.01或P<0.05）。聚类分析结果表明,春、夏两个季节均分为3个站位组,但是随季节变化站位分组有较大差异。春季两个近岸组之间的主要分歧种为斑鰶、短吻红舌鳎（Cynoglossus joyeri）、黄姑（Nibea albiflora）和多鳞鱚（Sillago sihama）;夏季区分近岸和远岸的主要分歧种为斑鰶、鳀、短吻红舌鳎,这几个物种都较多出现在近岸组。文章对山东半岛南部近岸海域鱼卵、仔稚鱼群落结构的空间格局及与环境因子的相关性进行了解析,为科学认识和保护该海域渔业资源及制定资源量化管理等措施提供依据和技术支撑。

关键词: 鱼卵, 仔稚鱼, 种类组成, 营养级, GAM模型, 群落结构