Resting cysts of planktonic dinoflagellates, once produced, sink to the seabed where they can remain viable for a long time. These cysts have important ecological roles, such as acting as the inoculum for the development of planktonic populations. Moreover, dinoflagellate cyst records from depth sediment cores are broadly used as a proxy to infer past environmental conditions. In this study, the main objective was to obtain information on the relationships between the spatial distribution of modern dinoflagellate cysts and present-day hydrography in the NW Iberian shelf. Cyst assemblages were analysed in 51 surface sediment samples with varying grain sizes, collected at different water depths, following nine transects perpendicular to the coast, between Aveiro and Figueira da Foz (Atlantic Iberian margin). Multivariate statistical analyses revealed marked land-sea and latitudinal gradients in the distribution of cysts, and helped investigate how environmental factors (water depth, grain size, sea-surface temperature (SST), sea-surface salinity (SSS), bottom temperature (BTT) and surface chlorophyll-a concentration (CHL)) influence modern dinoflagellate cyst composition and abundances. Three main ecological signals were identified in the modern dinoflagellate cyst assemblages: 1) the heterotroph signal as the main upwelling signal; 2) the dominance of P. reticulatum and L. polyedra signal, indicative of warm stratified conditions, possibly reflecting transitional environments between more active inshore upwelling and warmer offshore waters; and 3) the G. catenatum signal for the presence of mid-shelf upwelling fronts. The almost absence of viable cysts of the toxic and potentially toxic species G. catenatum L. polyedra and P. reticulatum suggests that in the study area, for these species, there is no build-up of significant cyst beds and thus planktonic populations must depend on other seeding processes. These results are the first detailed modern distribution of dinoflagellate cysts in the NW Iberian Atlantic margin (off Portugal), and show a good correspondence with hydrographic features of summer upwelling season in the study area, meaning that they are reflecting water column characteristics and therefore may be used as supporting evidence for the interpretation of stratigraphic cyst records and reconstruction of past marine ecosystems in W Iberia.

中文翻译：

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影响 Aveiro-Figueira da Foz（大西洋伊比利亚边缘）表层沉积物中空间甲藻囊肿分布的环境因素

浮游甲藻的休眠包囊一旦产生，就会沉入海床，在那里它们可以长期存活。这些包囊具有重要的生态作用，例如作为浮游种群发育的接种物。此外，来自深度沉积岩心的甲藻囊肿记录被广泛用作推断过去环境条件的代理。在这项研究中，主要目的是获得关于现代腰鞭毛虫囊肿空间分布与伊比利亚大陆架西北地区现代水文地理之间关系的信息。在阿威罗和菲盖拉达福斯（大西洋伊比利亚边缘）之间垂直于海岸的九个横断面之后，在不同水深收集的 51 个不同粒度的表层沉积物样品中分析了囊肿组合。多变量统计分析揭示了包囊分布的明显海陆梯度和纬度梯度，并有助于研究环境因素（水深、颗粒大小、海面温度 (SST)、海面盐度 (SSS)、底部温度 (BTT) ) 和表面叶绿素 a 浓度 (CHL)) 影响现代甲藻囊肿的组成和丰度。在现代甲藻囊肿组合中确定了三个主要的生态信号：1）异养信号作为主要的上升流信号；2) P. reticulatum 和 L. polyedra 信号的优势，表明温暖的分层条件，可能反映了更活跃的近岸上升流和更温暖的近海水域之间的过渡环境；和 3) 中陆架上升流前沿存在的 G.catenatum 信号。有毒和潜在有毒物种 G. catenatum L. polyedra 和 P. reticulatum 的存活囊肿几乎没有，这表明在研究区域，对于这些物种，没有明显的囊肿床堆积，因此浮游种群必须依赖在其他播种过程中。这些结果是第一次详细的现代伊比利亚大西洋边缘（葡萄牙附近）的甲藻囊肿分布，与研究区夏季上升流季节的水文特征有很好的对应关系，这意味着它们反映了水体特征，因此可能用作解释地层囊肿记录和重建西伊比利亚过去海洋生态系统的支持证据。reticulatum 表明，在研究区域，对于这些物种，没有明显的囊肿床堆积，因此浮游种群必须依赖于其他播种过程。这些结果是第一次详细的现代伊比利亚大西洋边缘（葡萄牙附近）的甲藻囊肿分布，与研究区夏季上升流季节的水文特征有很好的对应关系，这意味着它们反映了水体特征，因此可能用作解释地层囊肿记录和重建西伊比利亚过去海洋生态系统的支持证据。reticulatum 表明，在研究区域，对于这些物种，没有明显的囊肿床堆积，因此浮游种群必须依赖于其他播种过程。这些结果是第一次详细的现代伊比利亚大西洋边缘（葡萄牙附近）的甲藻囊肿分布，与研究区夏季上升流季节的水文特征有很好的对应关系，这意味着它们反映了水体特征，因此可能用作解释地层囊肿记录和重建西伊比利亚过去海洋生态系统的支持证据。