Data_Sheet_1_Zooplankton Fluctuations in the Surface Waters of the Estuary of a Large Subtropical Urban River.docx

The Danshuei River has a third largest catchment area and third longest in Taiwan. It flows through the capital, Taipei, and more than six million people live within its catchment area. Its estuary is characterized by a highly variable chemical and physical environment that is affected by the interaction of inland freshwater runoff with wastewater, and toward the coast is also influenced by the China Coastal Current and the Kuroshio Current. By collecting zooplankton bimonthly in 2014 from the surface layer (0–2 m depth) at five sites in the estuary, we were able to demonstrate that the composition of the zooplankton, and particularly its copepod fraction, varied significantly among sampling stations and months, thereby revealing seasonal succession. Fourteen higher taxa or other categories of zooplankter were identified, with the following being most common taxa: Decapoda, Copepoda (including Calanoida, Cyclopoida, and Harpacticoida), and “other larvae.” The Copepoda comprised 44 taxa (including eight only identified to genus) belonging to 3 orders, 17 families, and 29 genera, the five most abundant of which were Bestiolina n. sp. (undescribed), Corycaeus spp., Parvocalanus crassirostris, Acartia sp., and Paracalanus parvus. The highest and lowest copepod abundances were recorded in July (2557.88 inds. m–3) and January (1.3 inds. m–3), respectively. Observed changes in abundance of many kinds of copepod appeared to be significantly related to changes in physico-chemical parameters (e.g., salinity, temperature, pH, and dissolved oxygen concentration). Cluster analysis confirmed the existence of distinct copepod communities, each characterized by a preference for a different set of environmental conditions. Our comprehensive literature review of the copepod biodiversity of Taiwan’s major rivers for comparison with similar data compiled for other estuaries in the world, the first time such a review has been compiled, shows that 32 copepod taxa have been recorded from the brackish and freshwater parts of the Danshuei River. They represent 58.2% of the total number of brackish- and freshwater copepod species in Taiwan, and five of them have so far only been recorded in the Danshuei River: the calanoids Acartiella sinensis and Pseudodiaptomus forbesi, the cyclopoids Oithona fragilis and Oithona simplex, and the harpacticoid Tachidius (Tachidius) discipes.

台湾淡水河（Danshuei River）为台湾流域面积第三、河长第三的河流，流经台湾省会台北，其流域范围内居住人口逾六百万。该河河口的化学与物理环境高度多变，既受内陆淡水径流与废水的交互作用影响，近岸区域同时受中国沿岸流（China Coastal Current）及黑潮（Kuroshio Current）影响。2014年，研究团队于该河口的5个采样站位，每两月采集一次表层（水深0-2米）浮游动物（zooplankton）样本，结果显示浮游动物的组成，尤其桡足类（Copepoda）组分，在不同采样站位与月份间存在显著差异，由此揭示了其季节演替规律。本次研究共鉴定出14个高级分类阶元或其他类群的浮游动物，其中优势类群包括十足目（Decapoda）、桡足类（涵盖哲水蚤目（Calanoida）、剑水蚤目（Cyclopoida）及猛水蚤目（Harpacticoida））与「其他幼虫类群」。桡足类共包含44个分类单元（其中8个仅鉴定至属级），隶属于3个目、17个科、29个属，丰度最高的5个类群分别为未描述新种Bestiolina n. sp.、Corycaeus属物种、短足小哲水蚤（Parvocalanus crassirostris）、Acartia属物种及小拟哲水蚤（Paracalanus parvus）。桡足类丰度的最高值与最低值分别记录于7月（2557.88 个/立方米）与1月（1.3 个/立方米）。观测发现，多数桡足类的丰度变化与盐度、温度、pH及溶解氧浓度等理化参数的变化呈显著相关。聚类分析证实存在独特的桡足类群落，每个群落均偏好特定的环境条件组合。本研究首次针对台湾主要河流的桡足类生物多样性开展系统性文献综述，并与全球其他河口的同类数据进行对比，结果显示淡水河咸淡水及淡水区域共记录到32个桡足类分类单元，占台湾咸淡水与淡水桡足类物种总数的58.2%；其中5个类群仅在淡水河被发现：哲水蚤类中华伪镖水蚤（Acartiella sinensis）、福特假纺锤水蚤（Pseudodiaptomus forbesi），剑水蚤类脆弱大眼剑水蚤（Oithona fragilis）、简单大眼剑水蚤（Oithona simplex），以及猛水蚤类塔栖猛水蚤（Tachidius (Tachidius) discipes）。