Raphidiopsis raciborskii is being considered an expanding, invasive species all over the world. It is a potentially toxin producer cyanobacterium and form blooms specially in (sub)tropical lakes, causing concern to public health. Thus, controlling such phenomena are of vital importance. To test the hypothesis that a tropical clone of Daphnia laevis is able to reduce the biomass of R. raciborskii, we performed a mesocosm experiment simulating a bloom of this cyanobacterium in field conditions and exposing it to ecologically relevant densities of daphniids. In addition, we tested the hypothesis that omnivorous fish would be able to exert a top-down effect on Daphnia, decreasing the effectiveness of this control. We used treatments with (10 and 20 Daphnia L^-1) or without Daphnia and fish (3 per mesocosm). Daphnia was able to significantly reduce the biomass of R. raciborskii only at the highest density tested. Fish had low effect on Daphnia biomass, but it is suggested that nutrient recycling by fish might have contributed to the higher R. raciborskii biomass in fish treatments. This is the first evidence of Daphnia control over saxitoxin-producing cyanobacteria in a tropical ecosystem.

Raphidiopsis raciborskii被认为是世界范围内不断扩大的入侵物种。它是一种潜在的毒素生产者蓝藻，特别是在（亚）热带湖泊中形成水华，引起公众健康的关注。因此，控制此类现象至关重要。为了验证水蚤的热带克隆能够减少R. raciborskii生物量的假设，我们进行了一个中胚层实验，模拟了这种蓝藻在田间条件下的繁殖，并将其暴露于生态相关密度的水蚤。此外，我们测试了杂食性鱼类能够对水蚤施加自上而下影响的假设，从而降低了这种控制的有效性。我们使用了 (10 和 20Daphnia L ^-1 ) 或没有水蚤和鱼（每个中层 3 个）。只有在测试的最高密度下，水蚤才能显着降低R. raciborskii的生物量。鱼类对水蚤生物量的影响很小，但表明鱼类的养分循环可能有助于鱼类处理中较高的R. raciborskii生物量。这是水蚤控制热带生态系统中产生石房蛤毒素的蓝藻的第一个证据。