Dinophysis acuta and D. acuminata are associated with lipophilic toxins in Southern Chile. Blooms of the two species coincided during summer 2019 in a highly stratified fjord system (Puyuhuapi, Chilean Patagonia). High vertical resolution measurements of physical parameters were carried out during 48 h sampling to i) explore physiological status (e.g., division rates, toxin content) and ii) illustrate the fine scale distribution of D. acuta and D. acuminata populations with a focus on water column structure and co-occurring plastid-bearing ciliates. The species-specific resources and regulators defining the realized niches (sensu Hutchinson) of the two species were identified. Differences in vertical distribution, daily vertical migration and in situ division rates (with record values, 0.76 d-1, in D. acuta), in response to the environmental conditions and potential prey availability, revealed their niche differences. The Outlying Mean Index (OMI) analysis showed that the realized niche of D. acuta (cell maximum 7 × 103 cells L-1 within the pycnocline) was characterized by sub-surface estuarine waters (salinity 23 - 25), lower values of turbulence and PAR, and a narrow niche breath. In contrast, the realized niche of D. acuminata (cell maximum 6.8 × 103 cells L-1 just above the pycnocline) was characterized by fresher (salinity 17 - 20) outflowing surface waters, with higher turbulence and light intensity and a wider niche breadth. Results from OMI and PERMANOVA analyses of co-occurring microplanktonic ciliates were compatible with the hypothesis of species such as those from genera Pseudotontonia and Strombidium constituting an alternative ciliate prey to Mesodinium. The D. acuta cell maximum was associated with DSP (OA and DTX-1) toxins and pectenotoxins; that of D. acuminata only with pectenotoxins. Results presented here contribute to a better understanding of the environmental drivers of species-specific blooms of Dinophysis and management of their distinct effects in Southern Chile.

中文翻译：

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Dinophysis acuta 和 D. acuminata 在分层峡湾中的生态位分化。

Dinophysis acuta 和 D. acuminata 与智利南部的亲脂毒素有关。2019 年夏季，这两个物种的花朵在高度分层的峡湾系统（Puyuhuapi，智利巴塔哥尼亚）中同时开花。在 48 小时采样期间对物理参数进行了高垂直分辨率测量，以 i) 探索生理状态（例如，分裂率、毒素含量）和 ii) 说明 D. acuta 和 D. acuminata 种群的精细尺度分布，重点是水柱结构和共生的含质体纤毛虫。确定了两个物种的已实现生态位（sensu Hutchinson）的物种特定资源和监管机构。垂直分布、每日垂直迁移和原位分裂率的差异（记录值，0.76 d-1，在 D. acuta），为了应对环境条件和潜在的猎物可用性，揭示了它们的生态位差异。外围平均指数 (OMI) 分析表明，D. acuta 已实现的生态位（细胞最大 7 × 103 个细胞 L-1 在 pycnocline 内）的特征是地下河口水域（盐度 23 - 25），湍流值较低和PAR，还有狭窄的小众气息。相比之下，已实现的 D. acuminata 生态位（细胞最大 6.8 × 103 个细胞 L-1 正好在 pycnocline 上方）的特点是流出地表水更新鲜（盐度 17 - 20），具有更高的湍流和光强度以及更宽的生态位宽度. OMI 和 PERMANOVA 对共同发生的微浮游纤毛虫的分析结果与物种的假设一致，例如来自 Pseudotontonia 和 Strombidium 属的物种构成了 Mesodinium 的替代纤毛虫猎物。D. acuta 细胞最大值与 DSP（OA 和 DTX-1）毒素和果胶毒素有关；D. acuminata 仅含有果胶毒素。此处提供的结果有助于更好地了解 Dinophysis 物种特定繁殖的环境驱动因素，并管理其在智利南部的独特影响。