珠三角河网不同水文期浮游动物优势种及生态位

研究珠江三角洲河网水域不同水文期浮游动物的生态位,为进一步研究珠三角河网浮游动物种间竞争共存机制提供理论依据。2017-2018年在珠江三角洲河网设置13个调查站位,调查浮游动物在丰水期和枯水期组成与分布,分析浮游动物优势种组成、优势种生态位宽度值及优势种生态位重叠程度变化,并通过典范对应分析(CCA)研究优势种的生态位分化情况。结果表明:调查水域丰水期和枯水期分别检出浮游动物96和92种,广布中剑水蚤(Mesocyclops leuckarti)、右突新镖水蚤(Neodiaptomus schmackeri)、跨立小剑水蚤(Microcyclops varicans)等为珠三角河网水域浮游动物优势种;珠三角河网浮游动物在不同水文期各优势种的生态位宽度有差异,变化范围为1.04～4.02,主要由广生态位种群、中生态位种群和窄生态位种群组成;不同水文期各优势种的生态位重叠程度不均匀,在0～0.94,潜在的种间竞争压力较大;CCA分析结果表明,水温、溶解氧、总溶解性固体物质和总磷是影响珠三角河网浮游动物优势种生态位宽度的重要因素。不同水文期珠三角河网的生境条件变化引起浮游动物优势种生态位的差异,使得珠三角河网水域浮游动物的空间分布具有复杂性。

Dominant Zooplankton Species and Their Ecological Niches Under Different Hydrologic Regimes in Rivers of the Pearl River Delta

In this study, we investigated the ecological niche distribution of zooplankton in the river network of the Pearl River delta during flood and dry seasons. The relationship of niche differentiation with environmental factors was then analyzed using canonical correspondence analysis (CCA). The objective was to identify factors that influence spatial distribution of the zooplankton community in the delta and provide data for a mechanical study of zooplankton species competition and coexistence. In August 2017 (wet season) and February 2018 (dry season), zooplankton and water quality were monitored at 13 sampling stations. The study focused on species domination in the zooplankton community, changes in niche breadth and niche overlap of dominant zooplankton populations, and niche differentiation. The number of identified zooplankton species totaled 96 in the flood season and 92 in the dry season. Mesocyclops leuckarti, Neodiaptomus schmackeri, and Microcyclops varicans were the dominant species. The niche breadth of dominant zooplankton species varied with hydrological regime, ranging from 1.04 to 4.02. The ecological niche of dominant zooplankton populations included a broad niche, a medium niche and narrow niche. The degree of niche overlap among dominant species was also varied with hydrological regime, ranging from 0 to 0.94, indicating a large potential for inter-specific competition. CCA analysis showed that water temperature, dissolved oxygen, total dissolved solids and total phosphorus affected the ecological niche distribution of zooplankton in the Pearl River delta. Changes in habitat conditions from wet to dry season alter the ecological niche and the dominant zooplankton species, resulting a complex spatial distribution of zooplankton in the Pearl River delta.