Scleractinian diversity in the Dardanelles and Marmara Sea (Turkey): morphology, ecology and distributional patterns

Abstract

Although marine research on anthozoans began at the end of the 1800s with some reports on the occurrence in Turkey, comprehensive knowledge about their biotic features remains limited. This study is the first detailed diversity assessment of scleractinian corals inhabiting the Turkish waters. The surveys conducted on rocky habitats between 2011 and 2014 around the Dardanelles and Marmara Sea provided the distributional data of nine corals, five of which

Population dynamics of a temperate coral along a depth gradient in the Dardanelles

“…The substratum at the survey area is characterized by a dense occurrence of seagrass communities such as Posidonia oceanica and Zostera marina between 4 and 10 m and also by serpulid reefs and the only largest reef habitat of the endangered scleractinian coral Cladocora caespitosa in the Turkish Straits System (Özalp and Alparslan 2016). In the Dardanelles, B. europaea is recorded up to 23 m depth on rocks (Özalp et al 2014) and exceptionally on rhizomes of the Mediterranean endemic seagrass P. oceanica (Özalp and Alparslan 2016). In this region, L. pruvoti and Caryophyllia smithii are the dominant species between 41–50 m and 21–30 m, with a percent cover of 43% and 32%, respectively, while most B. europaea individuals occur between 11 and 20 m with a percent cover around 15% (maximum reported density is 393 individuals m −2 ; Özalp and Alparslan 2016).…”

“…Consequently, factors other than temperature have to be taken into account to explain these differences. The negative effects of the lower salinity on coral populations reported above 12 m depth in the Dardanelles (Baba et al 2007;Özalp and Alparslan 2016) may indeed play a role in determining a lower abundance than at Calafuria. Moreover, the Calafuria population occurred from 2 to 12 m with an average density of 16 individuals m −2 (Goffredo et al 2004), while in the Dardanelles it increased exponentially from 1 m (18 individuals m −2 ) to 21 m (548 individuals m −2 ).…”

“…The more saline waters at the deeper layer of the strait enable a great biodiversity in some locations and create hotspots for corals, sponges, tunicates, and other invertebrates of the coralligenous (Topçu and Özalp 2017). The substratum at the survey area is characterized by a dense occurrence of seagrass communities such as Posidonia oceanica and Zostera marina between 4 and 10 m and also by serpulid reefs and the only largest reef habitat of the endangered scleractinian coral Cladocora caespitosa in the Turkish Straits System (Özalp and Alparslan 2016). In the Dardanelles, B. europaea is recorded up to 23 m depth on rocks (Özalp et al 2014) and exceptionally on rhizomes of the Mediterranean endemic seagrass P. oceanica (Özalp and Alparslan 2016).…”

“…In contrast, poor information on this species is available for the eastern Mediterranean Sea. Investigations in the Turkish seas have focused on the distribution and ecological differences of scleractinians present in the eastern Mediterranean Sea (Özalp and Alparslan 2011). Among them, B. europaea has been observed as one of the most abundant solitary scleractinians, together with Leptopsammia pruvoti , Caryophyllia smithii , and Caryophyllia inornata (Özalp and Alparslan 2011, 2016).…”

“…Investigations in the Turkish seas have focused on the distribution and ecological differences of scleractinians present in the eastern Mediterranean Sea (Özalp and Alparslan 2011). Among them, B. europaea has been observed as one of the most abundant solitary scleractinians, together with Leptopsammia pruvoti , Caryophyllia smithii , and Caryophyllia inornata (Özalp and Alparslan 2011, 2016). In the Dardanelles, polyps of B. europaea are shorter in shallow‐water populations, possibly due to the stronger flows and wave action and/or as a morphological strategy of photoprotection under high‐light conditions (Özalp et al 2018).…”