Abstract. Corfu Island (Greece) is located in the northern Ionian Sea and exhibits unique and diverse marine coastal habitats suitable for high-diversity assemblages such as shallow-water foraminifera. The island also lies near the current range expansion front of the invasive species Amphistegina lobifera. We analyzed the foraminiferal assemblages of 51 samples from 25 sites around the island, calculated diversity indices, and analyzed the community structures of foraminiferal assemblages in comparison to local environmental variables. In addition to that, using the spatial structure or relative abundances, we evaluated the effect of A. lobifera on the species richness of all benthic foraminifera and habitat-specific groups. With 200 benthic foraminiferal species found, the high species richness and other diversity indices indicate Corfu as an area of high diversity. The main ecological drivers for the assemblage compositions were water depth, sediment texture, and habitat (especially vegetation), resulting in three main assemblage clusters around the island: (1) sandy or rocky, shallow-water areas from the south and west; (2) deeper areas from the west; and (3) rocky, vegetated areas of variable depths from the northwest and northeastern parts of the island. Our analyses suggest that the invasive species A. lobifera affects local diversity of the foraminiferal assemblage and that these effects become apparent when the invasive species accounts for more than 10 %–20 % of the total abundance. We also observed significant negative correlations with sessile epiphytes and smaller miliolids. Both groups share similar microhabitats with A. lobifera and might be outcompeted, which is probably further facilitated by ongoing ocean warming. However, other warm-affiliated taxa (e.g., other symbiont-bearing species) initially show a positive correlation with the increasing presence of A. lobifera until the latter exceeds 20 %. We expect that A. lobifera and other warm-adapted species will play an increasing role in shaping future biodiversity and assemblage composition in this area, a feature that supports the prognosed tropicalization of the Mediterranean Sea.

中文翻译：

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入侵的浅水有孔虫对当地生物多样性的影响主要是在密度超过 20% 时：科孚岛的案例

摘要。科孚岛（希腊）位于爱奥尼亚海北部，拥有独特而多样化的海洋沿海栖息地，适合浅水有孔虫等高多样性生物群落。该岛还靠近入侵物种 Amphistegina lobifera 目前的范围扩张前沿。我们分析了全岛 25 个地点的 51 个样本的有孔虫组合，计算了多样性指数，并与当地环境变量进行了比较，分析了有孔虫组合的群落结构。除此之外，利用空间结构或相对丰度，我们评估了 A. lobifera 对所有底栖有孔虫和栖息地特定群体的物种丰富度的影响。发现了 200 种底栖有孔虫物种，高物种丰富度和其他多样性指数表明科孚岛是一个高度多样性的地区。组合组成的主要生态驱动因素是水深、沉积物质地和栖息地（特别是植被），形成了岛屿周围的三个主要组合群：（1）南部和西部的沙质或岩石浅水区；(2)从西边更深的地区；(3) 岛屿西北部和东北部不同深度的岩石、植被区域。我们的分析表明，入侵物种 A. lobifera 影响了有孔虫组合的局部多样性，并且当入侵物种占总丰度的 10%–20% 以上时，这些影响变得明显。我们还观察到与无柄附生植物和较小的毫叶草呈显着的负相关。这两个群体与A. lobifera有着相似的微生境，并且可能会在竞争中被击败，而持续的海洋变暖可能会进一步促进这种情况。然而，其他温暖附属类群（例如其他共生体物种）最初显示出与A. lobifera 的存在增加呈正相关，直到后者超过20%。我们预计，A. lobifera 和其他适应温暖的物种将在塑造该地区未来的生物多样性和组合组成方面发挥越来越大的作用，这一特征支持了地中海预计的热带化。lobifera 直到后者超过 20%。我们预计，A. lobifera 和其他适应温暖的物种将在塑造该地区未来的生物多样性和组合组成方面发挥越来越大的作用，这一特征支持了地中海预计的热带化。lobifera 直到后者超过 20%。我们预计，A. lobifera 和其他适应温暖的物种将在塑造该地区未来的生物多样性和组合组成方面发挥越来越大的作用，这一特征支持了地中海预计的热带化。