Current status (as of end of 2020) of marine alien species in Turkey

Abstract

The 2020's update of marine alien species list from Turkey yielded a total of 539 species belonging to 18 taxonomic groups, 404 of which have become established in the region and 135 species are casual. A total of 185 new alien species have been added to the list since the previous update of 2011. The present compilation includes reports of an ascidian species (Rhodosoma turcicum) new to the marine fauna of Turkey and range extensions of six species. Among the established species, 105 species have invasive characters at least in one zoogeographic region, comprising 19% of all alien species. Mollusca ranked first in terms of the number of species (123 species), followed by Foraminifera (91 species), Pisces (80 species) and Arthropoda (79 species). The number of alien species found in seas surrounding Turkey ranged from 28 (Black Sea) to 413 (Levantine Sea). The vectoral importance of the Suez Canal diminishes when moving from south to north, accounting for 72% of species introductions in the Levantine Sea vs. only 11% of species introductions in the Black Sea. Most alien species on the coasts of Turkey were originated from the Red Sea (58%), due to the proximity of the country to the Suez Canal. Shipping activities transported 39% of alien species, mainly from the Indo-Pacific area (20%) and the Atlantic Ocean (10%). Misidentified species (such as Pterois volitans, Trachurus declivis, etc.) and species those classified as questionable or cryptogenic were omitted from the list based on new data gathered in the last decade and expert judgements. The documented impacts of invasive species on socio-economy, biodiversity and human health in the last decade as well as the legislation and management backgrounds against alien species in Turkey are presented.

Fig 1. Underwater photograph of Rhodosoma turcicum observed on a dead Pinna nobilis shell in Fethiye Bay (Levantine Sea).

Photograph by Melih Ertan ÇINAR.

Fig 2. Number of invasive, established and casual alien species in each taxonomic group.

Fig 3. Number of alien species in four seas surrounding Turkey, and their distributions to major groups and their establishment success in each sea.

PHY: Phytobenthos, FMR: Foraminifera, CNI: Cnidaria, POL: Polychaeta, ART: Arthropoda, MOL: Mollusca, ECH: Echinodermata, TUN: Tunicata, PIS: Pisces, OTH: Others.

Fig 4. The number of alien species found in grids of 15x15 km along the coasts of Turkey.

Fig 5. The number of alien species belonging to major groups found in grids of 15x15 km along the coasts of Turkey.

Fig 6. The distribution of invasive, established and casual alien species along the coasts of Turkey.

Fig 7. Changes in the number of alien species of taxonomic groups after the 2011’s species list.

Fig 8

Cumulative (upper) and new (lower) number of alien species in seas surrounding Turkey over years.

Fig 9. The primary pathways of introduction for the alien species along the coasts of Turkey.

Fig 10. The trends in the importance of primary pathways in species introductions in seas per decade.

Fig 11. The origins of alien species reported along the coasts of Turkey.

Fig 12. The habitats preferences of alien species on the coasts of Turkey.

Fig 13. Habitat preferences of alien species in taxonomic groups reported from the coasts of Turkey.

Fig 14. The number of alien species in major taxonomic groups found in the depth intervals.

Fig 15. The number of invasive alien species affecting to native biodiversity, habitats, human health and economy (positive or negative).

Fig 16

A—Caulerpa cylindracea observed at Ayvalık Islands Natural Park, forming dense populations at scars in the vicinity of Posidonia oceanica meadows (Photo: M.Bilecenoglu), B—Stypopodium schimperi forms dense populations at Turkish coasts (Photo: E. Taşkın), C—The famous “small pebble beach” at Kaş, Antalya Bay is currently covered entirely with Amphistegina lobifera tests (Photo: M.B.Yokeş), D–Several coastal fish species found shelter among long spines of Diadema setosum (Photo: M.Bilecenoglu), E—The Red Sea goatfish, Parupeneus forsskali, is currently the dominant alien mullid in several localities, often observed in association with Siganus spp. (Photo: M.Bilecenoglu), F–The venomous Plotosus lineatus is a marine health hazard (Photo: B.Selli).