Many cyanobacterial species co-occur commonly in a freshwater ecosystem and can be consumed simultaneously by zooplankton. Both Microcystis aeruginosa and Cylindrospermopsis raciborskii are the dominant species and coexist in eutrophic tropical waters, and they together are assumed to have exert a stronger effect on the life history traits of cladocerans than a single cyanobacterial species. In the present study, we tested the hypothesis with life-history experiments of Daphnia sienesis, a large cladoceran species in tropics. In the experiments, M. aeruginosa and C. raciborskii were used as a mixture of food with Chlorella pyrenoidosa for the experimental animals. D. sienesis showed excellent growth and survival on sole diets of C. pyrenoidosa (CP). By contrast, Daphnia's growth decreased significantly and reproduction was completely inhibited when cyanobacteria comprised 100% of the food offered. The supplementation of C. pyrenoidosa into cyanobacterial diets significantly decreased their harmful effects on Daphnia, who improved the life history traits with the reduction of cyanobacterial percentage in mixed foods, irrespective of cyanobacterial species. Compared with the cultures of D. sienesis fed with a single cyanobacteria species, the animals in the treatments fed both M.aeruginosa-FACHB469 (F469) and C. raciborskii N8 (N8) had a lower growth rate in all the proportion of C. pyrenoidosa (25% CP, 50% CP or 75% CP). The strongest synergistic inhibition by the two cyanobacterial strains was found in the treatments with the 25% CP (i.e., 25% CP + 37.5% F469 + 37.5% N8), and no animal survived to maturity and reproduced. Thus, the simultaneous exposure to the two cyanobacterial species should be taken into account in assessing the ecological risks of cyanobacterial blooms, since multiple cyanobacterial coexistence can result in strong synergistic inhibition on growth and reproduction of zooplankton.

中文翻译：

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水蚤的生活史反应同时暴露于铜绿微囊藻和拟南芥（cylindrospermopsis raciborskii）。

许多蓝细菌物种通常共同存在于淡水生态系统中，浮游动物可以同时食用它们。铜绿微囊藻和拟南芥都在富营养化的热带水域中共存，并且被认为对锁骨的生活史特征产生的影响要比单个蓝细菌强。在本研究中，我们使用水蚤（Daphnia sienesis）的生活史实验对这一假设进行了检验。在实验中，铜绿假单胞菌和拉氏梭菌被用作食物与小球藻的混合物，用于实验动物。在单独的C.pyrenoidosa（CP）日粮中，D。sienesis显示出极好的生长和存活。相比之下，水蚤 当蓝细菌占所提供食物的100％时，其生长显着下降，繁殖被完全抑制。在蓝藻类饮食中补充吡喃假单胞菌可显着降低其对水蚤的有害影响，无论混合食品中的蓝藻属种类如何，它们都会降低混合食品中蓝细菌的百分率，从而改善生活史特征。与饲喂单一蓝细菌菌种的D. sienesis培养物相比，饲喂M.aeruginosa-FACHB469（F469）和C. raciborskii N8（N8）的处理动物在所有比例的C中均具有较低的生长率。拟南芥（25％CP，50％CP或75％CP）。在使用25％CP（即25％CP + 37.5％F469 + 37.5％N8）的处理中，发现了这两种蓝细菌菌株最强的协同抑制作用，而且没有动物存活到成熟并繁殖。因此，在评估蓝藻水华的生态风险时，应考虑同时暴露于两种蓝藻菌种，因为多种蓝藻菌共存会严重抑制浮游动物的生长和繁殖。