大辽河口碎波带浮游动物群落结构的昼夜变化

2013年4月24-25日观察了大辽河口碎波带浮游动物群落结构的昼夜变化。结果表明：共采集浮游动物4类16种属，其中淡水种类11种，半咸水种类5种，优势种为砂壳虫（Difflugia sp.），螺形龟甲轮虫（Keratella cochlearis），桡足幼体（Copepodid）及剑水蚤（Cyclops sp）等；密度的峰值出现在4月24日8：00（4504.28ind.·L^-1），原生动物、轮虫类是影响密度变化的主要组成成分，占昼夜平均密度的78.0%；生物量高峰在4月25日20：00（23.757mg·L^-1），桡足类生物量占99.5%，占昼夜平均生物量的91.6%。大辽河口碎波带浮游动物种类与浮游植物种类、密度呈显著正相关。初春大辽河口浮游动物丰富，为鱼类性腺发育、繁殖创造了良好的生态环境。

Diurnal Rhythm of Zooplankton Community Structure in the Surf Zone of Daliaohe River Estuary in Spring

The diurnal rhythm of zooplankton community structure was investigated in the surf zone of Daliaohe River estuary on April 24-25, 2013. The results showed that the zooplankton assemblage was composed of 16 species in total, belonging to 4 taxonomic groups and 16 species or genera including 11 freshwater ones and 5 brackish ones, with predominant species were protozoa Difflugia sp.,rotifera Keratella cochlearis,copepoda copepodid and Cyclops sp. The peak zooplankton density （4504.28 ind.·L^-1） was observed at 8：00 a.m, protozoa and rotifera accounting for 78.0%of total density, and being the main factors affecting the diurnal rhythm of den-sity. The peak zooplankton biomass （23.757mg·L^-1） was found at 8：00 p.m on April 25, 2013, copepoda representing 99.5%of total biomass, and 91.6%of the average biomass. Moreover, the significant positive correlation was observed between the species composi-tion of zooplankton and the species composition and cell density of phytoplankton in the surf zone of Daliaohe River estuary. The abundant zooplankton in early spring provided a fairly good ecological environment for gonadal development, and reproduction of fishes.