Grazers can induce toxin (domoic acid, DA) production in diatoms. The toxic response has been observed in two species of Pseudo-nitzschia and was induced by Calanus copepods. In this study, interactions between diatoms and copepods were further explored using different species of diatoms and copepods. All herbivorous copepods induced toxin production, whereas exposure to carnivorous copepods did not. In line with this, increasing the number of herbivorous copepods resulted in even higher toxin production. The induced response is thus only elicited by copepods that pose a real threat to the responding cells, which supports that the induced toxin production in diatoms evolved as an inducible defense.

The cellular toxin content in Pseudo-nitzschia was positively correlated to the concentration of a group of specific polar lipids called copepodamides that are excreted by the copepods. This suggests that copepodamides are the chemical cues responsible for triggering the toxin production. Carnivorous copepods were found to produce less or no copepodamides.

Among the diatoms exposed to grazing herbivorous copepods, only two of six species of Pseudo-nitzschia and none of the Nitzschia or Fragilariopsis strains responded by producing DA, indicating that not all Pseudo-nitzschia species/strains are able to produce DA, and that different diatom species might have different strategies for coping with grazing pressure. Growth rate was negatively correlated to cellular domoic acid content indicating an allocation cost associated with toxin production. Long-term grazing experiments showed higher mortality rates of grazers fed toxic diatoms, supporting the hypothesis that DA production is an induced defense mechanism.

掠食者可以诱导硅藻中的毒素（Domoic acid，DA）产生。已在两种拟南芥中观察到了毒性反应，并且是由Calanus copepods诱导的。在这项研究中，使用不同种类的硅藻和co足类动物进一步探索了硅藻和co足类动物之间的相互作用。所有草食性pe足类动物都诱导毒素产生，而暴露于肉食性pe足类动物却没有。与此相符，增加草食co足类动物的数量导致更高的毒素产生。因此，诱导的应答仅由对反应细胞构成真正威胁的co足类引起，这支持了硅藻中诱导的毒素产生演变为诱导防御。

假性尼兹菌中的细胞毒素含量与被co足类分泌的一组称为copepodamides的特定极性脂质的浓度呈正相关。这表明co螨是引发毒素产生的化学线索。发现食肉的pe足类产生较少或没有produce足类。

间暴露于放牧食草桡足类的硅藻，只有两个六的物种的拟菱形藻和没有的菱形或Fragilariopsis菌株反应通过产生DA，表明并非所有拟菱形藻物种/株能够产生DA，并且不同的硅藻物种可能有不同的应对压力的策略。生长速率与细胞中的藻酸含量呈负相关，表明与毒素生产相关的分配成本。长期放牧实验表明，喂食有毒硅藻的放牧者死亡率更高，支持了DA产生是诱导防御机制的假说。