Bacterial Taxa Migrating from the Mediterranean Sea into the Red Sea Revealed a Higher Prevalence of Anti-Lessepsian Migrations.

In 1869, the Suez Canal was opened, which brought the waters of the Mediterranean and the Red Sea into direct contact. Notably, the Suez Canal was constructed for navigation purposes without focusing on the ecological impacts. The Suez Canal paved the way for species migration from the Red Sea to the Mediterranean Sea through Lessepsian migration, named after Ferdinand de Lesseps, while the migration from the Mediterranean Sea to the Red Sea is called the anti-Lessepsian migration. It has been argued in the past that the migrating species had negative consequences for the host environment as well as of humans. Few studies to date have attempted to map the microorganism migration problem because the traditional ways of measuring the community's richness and dissimilarities failed to provide enough detection of the migrating taxa. We collected 22 seawater samples from different locations in Egypt, in relationship to the migration across and to/from the Suez Canal. The V3-V4 regions of 16s genes were amplified and sequenced by the next generation Illumina MiSeq sequencer. Bioinformatics analysis revealed 15 taxa that migrated from the Mediterranean Sea to the Red Sea (i.e., anti-Lessepsian migration) such as the genera , , and Persicirhabdus. The family is the only one that migrated from the Red Sea to the Mediterranean Sea (Lessepsian migration). Seven anti-Lessepsian migrants colonized the Suez Canal more than the Mediterranean Sea such as the genera and . These findings collectively suggest that the anti-Lessepsian migration is more predominant than the Lessepsian migration in the bacterial community. This study paves the way for future research questions as well. For example, why is the anti-Lessepsian migration more common than the Lessepsian route in bacteria? Why do certain taxa stop migration at the Suez Canal, and why do certain taxa present in higher frequencies in the Suez Canal? Which taxa continue migration to the Indian Ocean and the Atlantic Ocean, and what is the impact of the anti-Lessepsian migration on the bacterial community? Understanding microbial diversity in a context of microorganism migration across seas and oceans remains a prime topic in biodiversity research and systems science.