Blooms of harmful algae are increasing globally, yet their impacts on copepods, an important link between primary producers and higher trophic levels, remain largely unknown. Algal toxins may have direct, negative effects on the survival of copepods. They may also indirectly affect copepod survival by deterring feeding and thus decreasing the availability of energy and nutritional resources. Here we present a series of short-term (24 h) experiments in which the cosmopolitan marine copepod, Acartia tonsa, was exposed to a range of concentrations of the toxic dinoflagellate, Alexandrium catenella (strain 1119/27, formerly Alexandrium tamarense), with and without the presence of alternative, non-toxic prey (Rhodomonas sp.). We also present the toxin profile concentrations for A. catenella. The survival and feeding of A. tonsa were not affected across the range of concentrations recorded for A. catenella in the field; increased mortality of A. tonsa was only discernible when A. catenella was present at concentrations that exceed their reported environmental concentrations by two orders of magnitude. The observed lethal median concentration (LC₅₀) for A. tonsa exposed to A. catenella was 12.45 ng STX eq L⁻¹. We demonstrate that A. tonsa is capable of simultaneously ingesting both toxic and non-toxic algae, but increases clearance rates towards non-toxic prey as the proportional abundance of toxic A. catenella increases. The ability to actively select non-toxic algae whilst also ingesting toxic algae suggests that consumption of the latter does not cause physical incapacitation and thus does not affect ingestion in A. tonsa. This work shows that short-term exposure to toxic A. catenella is unlikely to elicit major effects on the grazing or survival of A. tonsa. However, more work is needed to understand the longer-term and sub-lethal effects of toxic algae on marine copepods.

有害藻类的繁殖在全球范围内正在增加，但是它们对co足类的影响（主要生产者与较高营养水平之间的重要纽带）仍然未知。藻毒素可能对co足类动物的生存有直接的负面影响。它们还可能通过阻止进食而间接影响co足动物的生存，从而减少能量和营养资源的可利用性。在这里，我们提出了一系列短期（24 h）实验，其中将国际大都会co足纲螨纲（Acartiatona）暴露于一定浓度的有毒鞭毛藻亚历山大藻（1119/27株，以前是亚历山大塔玛伦塞），而且没有其他无毒的猎物（Rhodomonassp。）。我们还介绍了A. catenella的毒素谱浓度。在田野中记录到的A. catenella浓度范围内，A.tonsa的存活和觅食都没有受到影响。仅当链状土壤杆菌的浓度超过其报告的环境浓度两个数量级时，才可以发现扁桃体的死亡率增加。所观察到的致死浓度中位数（LC ₅₀为）A. tonsa暴露于链状亚历山大藻是12.45纳克STX当量大号^{- 1}。我们证明了A.tonsa能够同时摄入有毒和无毒藻类，但是随着有毒链霉菌比例丰度的增加，可增加对无毒猎物的清除率。主动选择无毒藻类并摄取有毒藻类的能力表明，食用无毒藻类不会引起身体的能力丧失，因此不会影响扁桃体的摄取。这项工作表明，短期暴露于有毒链状亚历山大藻不太可能引发对放牧或生存产生重大影响A. tonsa。但是，需要更多的工作来了解有毒藻类对海洋co足类动物的长期和亚致死作用。