The genus Amphistegina (benthic foraminifera): distribution along the southern Tunisian coast

The benthic foraminiferal genus Amphistegina is currently expanding its range in the Mediterranean Sea after being introduced through the Suez Canal from the Red Sea. Over the previous decade, Amphistegina spp. has colonized the eastern part of the Mediterranean Sea including the Egyptian and Libyan coasts, but the present southern limit in the Mediterranean Sea is along the southern Tunisian coast. However, this limit has never clearly been defined, and existing models predict an expansion along the entire Tunisian coastline. The Gulf of Gabes, in the southern part of Tunisia, is heavily polluted by local phosphate industries that discharge untreated waste directly into the sea. Amphistegina spp. is sensitive to water quality and marine pollution. Based on our surveys and recent investigations, the present distribution area of Amphistegina spp. along the south Tunisian coast includes the coastline east of Djerba Island, located in the Gulf of Gabes. Possible limiting factors for Amphistegina spp. expansion in the Gulf of Gabes may be the unfavourable environmental conditions generated by the phosphate industry.