杭州湾—舟山近海春季游泳动物群落结构及与环境因子的关系

杭州湾—舟山近海是许多经济鱼类的传统产卵地和栖息地,环境因子对鱼类群落结构的影响非常显著。本研究根据2016年春季在杭州湾—舟山近海的80个站位的底拖网调查数据,分析了鱼类及大型甲壳类群落数量和平均个体大小的空间分布,并根据典范对应分析法(CCA)研究了鱼类及大型甲壳类主要类群的特征(丰度和个体大小)与环境因子的关系。结果显示,游泳动物可分为5大类群(六丝钝尾虾虎鱼、底层鱼、中上层鱼、虾、蟹),每种类群的丰度平均分别为546、213、83、316和15个/h,平均个体大小分别为0.29、2.19、4.96、0.36和6.66 g/个。根据各类群的丰度、底温、底盐及表层浑浊度,将整个海域分为杭州湾内和舟山近海水域,绝大部分类群的丰度具有显著的区域差异性,而绝大部分类群的个体大小没有区域差异性。受到浑浊度、外海水团交汇的影响,绝大部分类群主要聚集在舟山近海的高生产力水域。CCA分析表明,2个轴的环境因子能解释丰度总变异的25%,而仅能解释个体大小总变异的11.7%,说明环境因子对于鱼类及甲壳类的类群的数量空间分布具有较大影响,而对于个体大小的分布影响较小。

Spring nekton community structure and its relationship with environmental variables in Hangzhou Bay-Zhoushan inshore waters

Hangzhou Bay-Zhoushan inshore waters are the home of many commercial fish species, providing a good place for spawning and habitats. The environments in these areas significantly affect the marine species and its structure. According to the bottom trawl survey, covering 80 stations, in these areas during spring, 2016, we studied the fish and macro-crustacean species assemblage and its spatial distribution. The canonical correspondence analysis (CCA) was used to reveal correlation between functional traits of fish and macro-crustacean species (abundance and size) and environmental variables. The results showed that all the marine species can be divided into five ecological groups (dominant group-Amblychaeturichthys hexanema, demersal fishes, pelagics, shrimp, and crab), with the average abundance 546, 213, 83, 316 and 15 individuals hour, respectively. The average size for these ecological groups was 0.29, 2.19, 4.96, 0.36 and 6.66 g/individual, respectively. According to five ecological group abundance, bottoms temperature, bottom salinity and surface turbidity, the waters were clustered into two areas: Hangzhou Bay and Zhoushan inshore waters. Abundance of most of the ecological groups significantly differed in two areas, while the size of most groups was not significantly different. As affected by the mixed waters of fresh water runoff and offshore waters, the large abundance of marine communities gathered in Zhoushan inshore areas, which was characterized by high primary production. The CCA analysis showed that environmental variables in the first two axes explained around 25% of the total variation of abundance, and only 11.7% of the total variation of the average size, indicating that the environmental variables played a more important role in explaining the spatial distribution of abundance than in explaining spatial distribution of average size.