Discovery of the extended distribution of Sabellaria reef to the Turkish Coast- the first report from the Black Sea

Abstract Reef building polychaetes are important ecosystem engineers by providing important biotic and abiotic ecosystem services, which makes them extremely important for soft bottom habitat health. Reefs built by Sabellarid polychaetes support costal biodiversity and abundance by providing shelter and nursery habitat for many different species including invertebrates and fish. Thus, it is important to understand their distribution range and pattern. Here, we report the extended distribution of Sabellaria reef from the Black Sea coast of Türkiye for the first time. According to morphological and molecular identifications, the species was identified as Sabellaria spinulosa (Leuckart, 1849) that form large reefs on coastal water of Europe. Sabellaria colonies that found at 4 stations in Ordu Province were examined according to 3 morphological characteristics based on scoring protocol for the ‘reefiness’. The two stations were classified as reefs as they meet the protocol criteria. Although the other two stations meet some criteria in terms of elevation and area, they were evaluated only as ‘potential reef areas’ due that they did not meet the patchiness criterion. Additionally, the results of the tube diameter and number of tubes were consistent with the findings from the reefs in the Mediterranean. The findings of this study add to our knowledge of Sabellaria reefs' wider geographic range and their potential adaptation to low salinity in the Black Sea. The existence of this new habitat is not only contribution to the biodiversity, but is also a potential candidate for the establishment of a marine protected area on the Black Sea coast of Türkiye.