Invasive alien species, introduced and/or spread outside their natural habitats, have affected native biodiversity in almost every ecosystem type on earth and are one of the greatest threats to biodiversity.
The Mediterranean Sea has been under tropicalization, and its warming is the one of the reason of the increase in the number of alien species in the Mediterranean. In recent years, there is increasing number of lessepsian invasion from Indo-Pacific and Red Sea which results in significant change of biodiversity in the Mediterranean. Some of endemic species is getting replaced with lessepsian species. Lessepsian species pressure on the Mediterranean species resulted in declining native species, and lessepsian species become more common in these areas by establishing their diet which also tend to increase the reproductive ability. The impacts of lessepsian species on their new environment include; restructuring established food webs, competition with native organisms for food and space and altering the gene pool when the invading organisms reproduce with native species, altering evolutionary processes and causing dramatic changes in native populations.
In addition, there are harmful effects of the alien species. These can be categorized as: (a) health problem (poisoning, pain) for fishermen, swimmers, divers, tourism, (b) net damages, (c) mesh clogging, (d) fouling and (e) extra labor for fishermen. There are three types of consequences of introduction of lessepsian immigrants in Turkey: ecological consequences, economic consequences, economic and ecological consequences