The Progressive Colonization of the Invasive Species Amphistegina lobifera on Pantelleria Island (Central Mediterranean, Sicily Channel).

Amphistegina lobifera, a symbiont-bearing benthic foraminifera native to the Indo-Pacific, is expanding its distribution range in the Mediterranean Sea due to ysian migration through the Suez Canal. This study investigates the colonization dynamics and ecological impact of A. lobifera on Pantelleria Island, which is located in the Central Mediterranean. Nine samples were collected from various substrates at different depths (-4 to -20 m) and analysed for composition, abundance, and ecological diversity. Results reveal a significant dominance of A. lobifera, especially in shallow unvegetated substrates, with relative abundances exceeding 50%. Conversely, more vegetated substrates host more diverse and balanced assemblages. Diversity indices are consistently lower where A. lobifera is dominant, indicating reduced biodiversity. Comparison with similar studies in Malta, Linosa, and Corfu confirms a 20% relative abundance threshold for A. lobifera as indicative of potential ecological imbalance. The results suggest that it represents a growing threat to native microbenthic biodiversity and reinforce its usefulness as a bioindicator species. Pantelleria represents a key transition zone for monitoring the dynamics of invasive species in the Mediterranean, and this study highlights the urgent need for long-term surveillance of benthic biodiversity.