春季大辽河口碎波带浮游植物群落结构的昼夜变化

大辽河口地处辽东湾北岸，在辽宁省营口市汇入渤海。2013年春季对大辽河口碎波带浮游植物的群落结构进行了昼夜采样调查。结果表明，春季大辽河口碎波带浮游植物共计8门76种属，数量、生物量均值总计分别为373．83x10ind·L-1、2．5753mg·L-1。浮游植物以硅藻和绿藻的种类组成、数量为主（硅藻34种属，167．45×104ind·L-1；绿藻22种属，137．36×104ind·L-1），生物量以硅藻为主（73．7％）。优势种主要是硅藻门的种类，优势种中除普生性种类、中盐性种类外，广温、广盐的中肋骨条藻Skeletonemacostatum、扁藻Platymonassp．也占优势。春季大辽河口碎波带浮游植物呈现出明显的昼夜变化，浮游植物种类组成、数量的昼夜变化高峰出现在12：00和0：00，生物量高峰出现在16：00。浮游植物的种类数（P=0．013）、数量（P=0．002）与盐度呈显著负相关；生物量与温度呈显著正相关（P=0．019）。

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

Daliaohe River estuary is located in north Liaodong Bay, and Daliaohe River flows into the Bohai Sea. The diurnal rhythm of phytoplankton community structure was investigated in the surf zone of Daliaohe River estuary in spring of 2013. The results showed that the phytoplankton assemblage was composed of 76 species in total, belonging to 8 taxonomic groups. The phytoplankton was 373.83 x 104ind .L-1 in average cell density and had biomass of 2.5753mg L-1. The species composition and cell density of Bacillariophyta （34 taxa and 167.45~ 104ind＇L-1） and Chlorophyta （22 taxa and 137.36 104ind＇L-t） were dominant in the surf zone of Daliaohe River estuary. At the same time, the biomass of Bacillariophyta （73.7%） was dominant in the investigation area. Bacillariophyta were mainly in dominant species. Except that there were widespread and mesohalinous species in dominant species, euryhalinous and eurythermal algae Skeletonema costatum and Plotymor~as sp. were dominant species in the investigation area. Diurnal rhythm of phytoplankton community structure was obvious in the surf zone of Daliaohe River estuary in spring. There was the diurnal rhythm of species composition and cell density, two peaks at 12：00 and 0：00. On the other hand, the diurnal rhythm of biomass was observed in phytoplankton, a peak at 16：00. Moreover, the significant negative correlation was found between the species composition （P=0.013） and cell density （P-0.002） in phytoplankton, and the significant positive correlation was observed between the biomass （P=0.019） of phytoplankton and the water temperature.