Composition and abundance of octocorals in the Sea of Marmara, where the Mediterranean meets the Black Sea

Abstract

Summary:Species composition and abundance of octocoral assemblages were investigated in the Sea of Marmara, which forms the connection between the Mediterranean and the Black Seas, two semi-enclosed seas with peculiar oceanographic conditions. Fourteen octocoral species were collected in the saline layer of the Marmara Sea (20-40 m), with a mean coral abundance of 5.21±5.11 colonies m -2 (mean ± SD) calculated from a total of 1390 colonies counted in transects. In spite of severe anthropogenic disturbances, dense assemblages of corals/gorgonians were observed during this study. The coralligenous communities-one of the most valuable structures of the Mediterranean Sea-harbored either Eunicella cavolini or Paramuricea macrospina as the dominant gorgonian in the Marmara Sea. Furthermore, the gorgonian assemblages of the Marmara Sea differed from those of the Mediterranean in their high abundance of P. macrospina and Spinimuricea klavereni, two species rarely encountered in the Mediterranean Sea at the studied depth range. The factors behind the observed differences are discussed in regard to the particular oceanographic conditions of the Marmara Sea. Finally, we revised the main threats to corals/gorgonians in the Marmara Sea and provided some insights on management recommendations for coral conservation in this area.

Contrasted levels of genetic diversity in a benthic Mediterranean octocoral: Consequences of different demographic histories?

“…This is particularly important when considering the current pressures on this species. In Turkey, some relatively dense E. cavolini populations, restricted to few areas in the Marmara Sea, are under various threats such as fisheries (Topçu & Öztürk, 2015). Their genetic particularity could make these populations more vulnerable against such threats that tend to lower their abundance.…”

Alcyonacea awakens: Palaeobiology and palaeoecology of Palaeozoic octocorals known from their sclerites

“…Alcyonacean genera show a wide geographic and bathymetric distribution (Devictor & Morton, ; Fabricius & Alderslade, ; McFadden & Hochberg, ; Pérez, De Moura Neves, Cordeiro, Williams, & Cairns, ), and they occur in nearly all kinds of modern marine environments, from nearshore to deep waters. However, they need to grow on hard substrates that can be extensive or discrete if they are in sandy or muddy bottoms (Topçu & Öztürk, ; Verseveldt, ) and are usually also attached to stones or shells in these soft bottoms (Weinberg, ).…”

“…Recent Alcyonacean soft corals are able to attach themselves to very different substrates, both abiogenic (rock walls, promontories, cavities, fissures, boulders, etc.) and biogenic (hard shells and skeletons; Bo et al, ; Groot & Weinberg, ; McFadden & Hochberg, ; Stokvis & van Ofwegen, ; Topçu & Öztürk, ; van Ofwegen et al, ; Verseveldt & van Ofwegen, ). Biogenic substrates can be dead (post‐mortem overgrowth) or alive (live–live interaction or syn‐vivo sensu Fagerstrom, West, Kershaw, & Cossey, ).…”

“…Recent Alcyonacean soft corals are able to attach themselves to very different substrates, both abiogenic (rock walls, promontories, cavities, fissures, boulders, etc.) and biogenic (hard shells and skeletons; Bo et al, 2011;Groot & Weinberg, 1982;McFadden & Hochberg, 2003;Stokvis & van Ofwegen, 2006;Topçu & Öztürk, 2015;van Ofwegen et al, 2007;Verseveldt & van Ofwegen, 1992).…”

Reproduction in the Mediterranean endemic gorgonian Spinimuricea klavereni (Anthozoa, Octocorallia, Plexauridae)

“…The northern Marmara Sea is also a highly disturbed environment. Human‐induced disturbances to gorgonians in the Marmara Sea include high pollution, mucilage events, and fishing (Topçu & Öztürk ).…”