Characteristics of the Mesophotic Megabenthic Assemblages of the Vercelli Seamount (North Tyrrhenian Sea)

Abstract

The biodiversity of the megabenthic assemblages of the mesophotic zone of a Tyrrhenian seamount (Vercelli Seamount) is described using Remotely Operated Vehicle (ROV) video imaging from 100 m depth to the top of the mount around 61 m depth. This pinnacle hosts a rich coralligenous community characterized by three different assemblages: (i) the top shows a dense covering of the kelp Laminaria rodriguezii; (ii) the southern side biocoenosis is mainly dominated by the octocorals Paramuricea clavata and Eunicella cavolinii; while (iii) the northern side of the seamount assemblage is colonized by active filter-feeding organisms such as sponges (sometimes covering 100% of the surface) with numerous colonies of the ascidian Diazona violacea, and the polychaete Sabella pavonina. This study highlights, also for a Mediterranean seamount, the potential role of an isolated rocky peak penetrating the euphotic zone, to work as an aggregating structure, hosting abundant benthic communities dominated by suspension feeders, whose distribution may vary in accordance to the geomorphology of the area and the different local hydrodynamic conditions.

Shedding light on an East-Mediterranean mesophotic sponge ground community and the regional sponge fauna

“…Primers used for the PCR amplifications are listed in Table S2 (in the Supplement). The 18S rDNA gene was amplified using the primer sets 18S1/18S2 (Borchiellini et al, 2001). If nothing was obtained in the first (external) PCR, re-amplification was performed in two overlapping fragments using the primer-pairs 18S1/18S6 and 18S3/18S2.…”

“…Due to its inaccessibility by scuba diving, until recently it was therefore one of the less-studied habitats in the ocean (Lesser et al, 2009). Thus, basic information on the mesophotic sponge communities, including community composition, species depth range, habitat preferences, and species abundance and distribution, are scarce worldwide (Bo et al, 2011;Schönberg et al, 2012;Olson et al, 2013;Slattery et al, 2015). Furthermore, the processes that structure these communities are virtually unknown.…”

Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management

“…Sheltered hydrodynamic conditions naturally increase the abundance of active, rather than passive, filter-feeders, favouring thus the dominance of various species of sponges and ascidians (Bo et al, 2011); many such species have been shown to contain some of the most bioactive chemicals, providing, thus, useful insight to pharmaceutical research (Uriz et al, 1991). Sheltered conditions also increase human access and activities, rendering these communities more popular to recreational and professional fishermen, as well as scuba divers.…”

Changes in polychaete standing stock and diversity on the northern side of Senghor Seamount (NE Atlantic)

“…The high global abundance of seamount ecosystems still represents an immense challenge to scientists, thus it is somewhat unsurprising that < 0.3 % have been sampled biologically in any detail, despite significant interest in these features (Ramirez-Llodra et al, 2010). Seamounts are often typified by highly rich and diverse communities of predominantly large suspension feeding organisms such as gorgonians and antipatharian corals, which are often the focus of seamount research (Bartsch, 2008;McClain et al, 2009;Clark et al, 2010;McClain, 2010;Rowden et al, 2010;Simpson and Watling, 2010;Bo et al, 2011;Sautya et al, 2011;Tracey et al, 2011). Many studies have also concentrated upon seamount fish populations (Clark, 1999;Matthiesson et al, 2002;Diekmann, 2006;Christiansen et al, 2009a;Menezes et al, 2009;Morato et al, 2009;Hirch and Christiansen, 2010) with relatively few focussed upon the infauna Dauvin, 2000, 2003;Richer De Forges et al, 2000;Koslow et al, 2001;Surugiu et al, 2008).…”