Interannual fluctuations in the structure and the composition of ichthyoplankton assemblages in the pelagic waters of the Strait of Sicily (SoS, Central Mediterranean) were investigated, trying to relate them to the observed variability in oceanographic conditions. Plankton data used in this study were from 16 summer surveys carried out in the SoS every year from 2001 to 2016, using oblique bongo plankton net (0–100 m) tows. Out of more than 12,000 fish larvae collected in the sampling stations included in the analysis, 9,519 of them were identified and regularly classified in 15 orders and 49 families. Ichthyoplankton assemblages, defined at the family level due to the uniform availability of this information along the time series, showed a decreasing trend over time in total larval abundance, along with taxonomic (family) richness and Shannon index (α diversity), more pronounced in the shelf area and in the slope area, respectively. Conversely, the relatively high levels of yearly compositional changes observed in the larval assemblage from both shelf and slope areas, as estimated by the Jaccard dissimilarity index (β diversity), did not show any significant linear trend. In addition, a biodiversity hotspot (both in terms of family richness and Shannon index) was evidenced in the frontal structure characterizing the southeastern part of the study area. Generalized additive models were used to evaluate the effect of oceanographic conditions on the temporal and spatial patterns of ichthyoplankton biodiversity. Results evidenced the role of salinity, surface temperature, and surface currents in modulating biodiversity indices, especially in the shelf area. Finally, the relevance of local frontal oceanographic structures in sustaining high biodiversity levels is postulated.

研究了西西里海峡（SoS，地中海中部）中上层水域中浮游鱼类组合结构和组成的年际波动，试图将它们与观察到的海洋条件变化联系起来。本研究中使用的浮游生物数据来自 2001 年至 2016 年每年在 SoS 进行的 16 次夏季调查，使用倾斜的邦戈浮游生物网（0-100 m）拖网。在纳入分析的采样站收集的 12,000 多条鱼类幼虫中，其中 9,519 条被识别并定期分类为 15 目和 49 个科。由于这些信息在时间序列中的统一可用性，在科水平上定义的浮游鱼类组合显示出总幼虫丰度随时间下降的趋势，随着分类（科）丰富度和香农指数（α多样性），分别在陆架区和斜坡区更为明显。相反，根据 Jaccard 差异指数（β 多样性）估计，在陆架和斜坡区域的幼虫组合中观察到的相对较高水平的年度成分变化没有显示出任何显着的线性趋势。此外，在研究区东南部的锋面结构中证实了生物多样性热点（无论是家庭丰富度还是香农指数）。广义加性模型用于评估海洋条件对浮游鱼类生物多样性时空格局的影响。结果证明了盐度、地表温度和地表水流在调节生物多样性指数中的作用，尤其是在货架区。最后，假设局部正面海洋结构在维持高生物多样性水平方面的相关性。