Biodiversity Changes Along The Algerian Coast (Southwestern Mediterranean Basin) From 1834 To 2017. First Assessment Of Introduced Species

The "Introduced" species of the Algerian coast remain the most undocumented issue in the Mediterranean Sea. Only few studies have been dedicated to Introduced species due to the lack of taxonomists. In-depth research on introduced species along the Algerian coast should provide new data that could explain the spreading mechanisms in the southwestern part of the Mediterranean basin, particularly near the Alboran Sea. Introduced species and other related research, the outcome of which is expected in the next few years, is in progress in the southwestern Mediterranean basin. The aim of this work is to provide an inventory of available data pertaining to marine species "introduced" in Algerian waters, whether these species were introduced intentionally or accidentally. The large number of introduced species records covers the period from 1834 to December 2017. Seventy "Introduced" species have been recorded along the Algerian coast, composed of true aliens (55.7%), range expanding species (25.7 %), cryptogenic species (15.7%) and vagrant species (2.9%), with a clear dominance of fish (38.57%) and macroalgae (30%). Approximately 348 introduction events have been reported; 64.9 % of them belong to macroalgae and one sighting out of two is made in the central region. The distribution and the status of introduced species in Algeria were evaluated. In total, 20% of the Introduced species can be considered as established along the Algerian coast, in particular the macrophyta, Codium fragile and Ulva lactuca as well as the cryptogenic species, Oculina patagonica, while Asparagopsis armata, A. taxiformis and Caulerpa cylindracea are considered as invasive.