绿藻浒苔对浮游植物群落结构影响研究

Influence of Enteromorpha prolifera (Chlorophyta) on the phytoplankton community structure

为了解浒苔(Enteromorpha prolifera)对浮游植物群落的影响,于2011年7月末在青岛第三海水浴场附近海域,现场采集了浒苔鲜组织和含自然浮游植物群落的海水,进行了10d的浒苔与浮游植物群落室内受控共培养实验。设计4个处理,包括1个对照组和3个实验组,每个处理设置3个平行。对照组未添加浒苔,实验组分别按照0.8(低)、2.4(中)和7.2 g/L(高)的湿质量进行添加。研究结果表明,在整个共培养期间,硅藻的生长受到了浒苔明显的抑制,在3个不同的实验组细胞丰度显著降低(ANOVA,P<0.05),降幅分别达到84.1%、92.1%和95.3%。优势种长菱形藻(Nitzschia longissima)在高实验组的第10天,细胞丰度更是低至对照组的0.38%。甲藻丰度在各组皆表现出先升高后降低的趋势,优势种利玛原甲藻(Prorocentrum lima)在高实验组的第3天,细胞丰度高达对照组的98.7倍。浒苔通过影响浮游植物细胞丰度和优势种演替,改变了浮游植物的群落结构。高密度浒苔的存在会使浮游植物优势种组成趋于单一,物种多样性程度和群落稳定性大为降低。但是,浒苔对单细胞浮游植物的克生作用可以抑制赤潮藻的过度繁殖,有益于赤潮的生物防治和水域环境的生态修复。

The rapid proliferation of Enteromorpha prolifera （Chlorophyta） formed the ＂green tides＂ which influ- enced the onshore area of Qingdao city in recent years. In order to evaluate the influence of this macroalgae on the community structure of natural phytoplankton, fresh tissue of E. prolifera and phytoplankton seawater were sam- pled near the third bathing beach of Qingdao at the end of July 2011. The cocultivation experiment of E. prolifera and phytoplankton was lasting ten days under controlled conditions in the laboratory. Four treatments were designed including one control group and three experimental groups, with three paralleled samples in each treatment. No E. prolifera was added to the control group whilst 0.8 （low）, 2.4 （medium） and 7.2 g wet/L （high） fresh tissue were added to the experimental groups. The results showed that diatoms were inhibited during the cultivation period, with significant low cell abundance in the three experiment groups （P〈0.05）, averaging 84.1%, 92.1% and 95.3% reduction compared with the control group respectively. The cell abundance of predominant species Nitzschia long- issima in the high experimental group was only 0.38% of that in the control group in the tenth day. The cell abun- dance of dinoflagellates increased from the beginning of the cultivation and fell back during the late period in all treatments. The cell abundance of predominant species Prorocentrum lima in the high experimental group was 98.7 times higher than that in the control group in the third day. The existence of E. prolifera altered the community structure of natural phytoplankton through the influence on the cell abundance and predominant species succession. The composition of predominant species would become simplified whilst the species diversity and the robust sta- bility of phytoplankton community would lose. However, due to the allelopathic effect of E. prolifera on the single cell phytoplankton species, the blooms of those red-tides species in natural seawaters would be inhibited, favoring for the prevention of red tide in coastal regions of China Seas and the ecological restoration of aquatic environments.