Persistence of Pristine Deep-Sea Coral Gardens in the Mediterranean Sea (SW Sardinia)

Abstract

Leiopathes glaberrima is a tall arborescent black coral species structuring important facies of the deep-sea rocky bottoms of the Mediterranean Sea that are severely stifled by fishing activities. At present, however, no morphological in vivo description, ecological characterization, age dating and evaluation of the possible conservation actions have ever been made for any population of this species in the basin. A dense coral population was reported during two Remotely Operated Vehicle (ROV) surveys conducted on a rocky bank off the SW coasts of Sardinia (Western Mediterranean Sea). L. glaberrima forms up to 2 m-tall colonies with a maximal observed basal diameter of nearly 7 cm. The radiocarbon dating carried out on a colony from this site with a 4 cm basal diameter revealed an approximately age of 2000 years. Considering the size-frequency distribution of the colonies in the area it is possible to hypothesize the existence of other millennial specimens occupying a supposedly very stable ecosystem. The persistence of this ecosystem is likely guaranteed by the heterogeneous rocky substrate hosting the black coral population that represents a physical barrier against the mechanical impacts acted on the surrounding muddy areas, heavily exploited as trawling fishing grounds. This favorable condition, together with the existence of a nursery area for catsharks within the coral ramifications and the occurrence of a meadow of the now rare soft bottom alcyonacean Isidella elongata in small surviving muddy enclaves, indicates that this ecosystem have to be considered a pristine Mediterranean deep-sea coral sanctuary that would deserve special protection.

New Mediterranean Biodiversity Records (November, 2016)

“…The presence of Isidella elongata has been mentioned in the Mediterranean Sea by several researchers (e.g. Watling et al, 2011 and references therein;Bo et al, 2015 and references therein), and is considered as very limited nowadays presumably due to trawling (Bo et al, 2015). No records of Acanella spp have been reported in the area to date.…”

First attempts towards the restoration of gorgonian populations on the Mediterranean continental shelf

“…However, since commercial fish species are often associated with these communities, they are largely exploited by artisanal fishermen using trammel nets and longlines (Deidun et al, ; Mytilineou et al, ). The entire removal or partial damage of coral and gorgonian colonies caused by fishing gears can have far‐reaching and long‐lasting effects, undermining the long‐term viability of their populations (Bo, Cerrano, et al, , Bo et al, ), since they are long‐lived, slow‐growing species, with delayed sexual maturity and limited recruitment success (Coma, Ribes, Zabala, & Gili, ; Garrabou & Harmelin, ; Linares, Doak, Coma, Díaz, & Zabala, ).…”

Description of a new species of Leiopathes (Antipatharia: Leiopathidae) from the Hawaiian Islands

“…nov. colonies are fan-like and bright orange in situ (Fig. 1a, 3a-h), whereas living colonies of L. glaberrima are grayish-white, white, pale orange or bright orange, and branched irregularly (Bo 2008;Vertino et al 2010;Mastrototaro et al 2010;Bo et al 2015). Leiopathes glaberrima has been reported to occur at depths as shallow as 37 m in the Gulf of Mexico (Opresko 2009) and as deep as 1532 m off Morocco (Grasshoff 1989), whereas L. annosa sp.…”

“…7). In contrast, L. glaberrima has been recorded from widespread geographic locations, including from throughout the Mediterranean (Gray 1857;Opresko & Baron-Szabo 2001;Bo 2008;Carlier et al 2009;Sinninger & Pawlowski 2009;Deidun et al 2010;Vertino et al 2010;Mastrototaro et al 2010;D'Onghia et al 2012;Brugler et al 2013;Angeletti et al 2014;Bo et al 2014aBo et al , 2014bBo et al , 2015Fabri et al 2014;Ingrassia et al in press), the northeastern Atlantic (Johnson 1899;Grasshoff 1985Grasshoff , 1989Brito & Ocaña 2004), the northwestern Atlantic and Caribbean (Brook 1889;Cairns et al 1993;Williams et al 2006Williams et al , 2007Opresko 2009) (Fig. 7).…”