Many regions of Antarctica are classified as high nutrient low chlorophyll (HNLC) areas. In these, iron availability is limiting primary productivity and subsequent carbon export. Domoic acid (DA) has previously been detected in the Southern Ocean and suggested to act as a ligand that facilitates iron assimilation for Pseudo-nitzschia spp., species that contribute to Antarctic diatom blooms. An incubation experiment using the Antarctic species Pseudo-nitzschia subcurvata was performed in Antarctic seawater at low and high iron concentrations. Dissolved DA was added to one set of each of the two treatments. This was done to verify whether DA positively affects the growth of the non-toxic species Pseudo-nitzschia subcurvata and increases its cellular iron content, particularly under low iron conditions. We hypothesize that (i) DA is taken up under low iron conditions (ii) that more iron is taken up if DA is available and (iii) that the growth rate increases in the presence of DA. We showed that P. subcurvata did not take up any added DA, even under low iron conditions. Additionally and contrary to our hypothesis, the cells were not positively influenced by the addition of dissolved DA in terms of growth rate, cellular iron and carbon content. Hence, there was no significant difference in iron content between the different treatments. However, the cellular copper content increased under low iron conditions when DA was added. This study suggests that dissolved DA in naturally occurring concentrations does not increase bioavailability of iron to P. subcurvata and that only species producing DA might benefit from it.

中文翻译：

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溶解的软骨藻酸不会提高铁胁迫的 Pseudo-Nitzschia subcurvata 的生长速度和铁含量

南极洲的许多地区被归类为高营养低叶绿素 (HNLC) 地区。其中，铁的可用性限制了初级生产力和随后的碳输出。先前已在南大洋中检测到软骨藻酸 (DA)，并建议其作为一种配体，促进 Pseudo-nitzschia spp.（有助于南极硅藻大量繁殖的物种）的铁同化。使用南极物种 Pseudo-nitzschia subcurvata 在南极海水中进行了低铁和高铁浓度的孵化实验。将溶解的 DA 添加到两种处理中的每一种中。这样做是为了验证 DA 是否对无毒物种 Pseudo-nitzschia subcurvata 的生长产生积极影响并增加其细胞铁含量，尤其是在低铁条件下。我们假设 (i) DA 在低铁条件下被吸收 (ii) 如果 DA 可用，则吸收更多的铁和 (iii) 在 DA 存在下生长速率增加。我们表明，即使在低铁条件下，P. subcurvata 也不吸收任何添加的 DA。此外，与我们的假设相反，细胞在生长速率、细胞铁和碳含量方面不受添加溶解 DA 的积极影响。因此，不同处理之间的铁含量没有显着差异。然而，当添加 DA 时，在低铁条件下细胞铜含量增加。这项研究表明，天然浓度的溶解 DA 不会增加铁对 P. subcurvata 的生物利用度，并且只有产生 DA 的物种可能会从中受益。