New records of recently described chemosymbiotic bivalves for mud volcanoes within the European waters (Gulf of Cádiz)

Abstract

Chemosymbiotic bivalves are important members of cold seep communities and information on their distribution in the European waters is still quite scarce. This study reports the presence of living populations and shell remains of some recently described bivalves such as Lucinoma asapheus, Solemya elarraichensis and Acharax gadirae as well as Bathymodiolus sp. in the mud volcanoes of the Spanish Atlantic waters. Living populations of these species were thus far only found in Anastasya, Aveiro and Almazán mud volcanoes, together with other chemosymbiotic metazoa (Siboglinum spp.), suggesting the presence of moderate seepage activity. In other mud volcanoes (Albolote, Gazul), the benthic communities are dominated by sessile filter feeders on authigenic carbonates (chimneys, slabs) and only the shell remains of some chemosymbiotic bivalves were found, indicating earlier or very low seepage conditions. The present study elaborates on the known distribution of L. asapheus and S. elarraichensis to the European waters of the Gulf of Cádiz.

Ocean Circulation Over North Atlantic Underwater Features in the Path of the Mediterranean Outflow Water: The Ormonde and Formigas Seamounts, and the Gazul Mud Volcano

“…The Gazul mud volcano is located in the continental slope of the Gulf of Cadiz (Palomino et al, 2015). Gazul is sculpted by the MOW, which has carved two downstream depressions at both sides of the structure, whereas its rear sector has a peculiar saddle shape as result of the low velocities that enable sedimentation (Rueda et al, 2012;Palomino et al, 2016). The Ormonde seamount forms part of the Gorringe Bank at around 125-150 miles west-southwest of Cape St. Vincent.…”

Spatial characterization of megabenthic epifauna of soft bottoms around mud volcanoes in the Gulf of Cádiz

“…The absence of chemosymbiotic species in the samples is mainly due to the sampling method used, which mostly targets large epifaunal and demersal species, and to the fact that samples were taken in adjacent bottoms of mud volcanoes without fluid venting. Nevertheless, a recent study on infauna of mud volcanoes from El Laberinto (Anastasya, Pipoca and Tarsis) using different sampling methods (box-corer, benthic dredge, beam trawl) to the one used for this study (otter trawl) have highlighted the presence of chemosymbiotic bivalves, frenulate polychaetes and interesting habitats that deserve conservation (cold water corals, sponge and gorgonian aggregations) in these mud volcanoes (González-García 2011;Rueda et al 2012a;Rueda et al 2012b). Previous studies have also found chemosymbiotic-based communities in mud volcanoes on the Moroccan margin (Cunha et al 2002Rodrigues et al 2008;Vanreusel et al 2009;Oliver et al 2011).…”

“…This contrasts the strong differences observed in the benthic communities and habitats of the summits and sides of mud volcanoes of El Laberinto using different sampling techniques (González-García 2011). These include chemosynthesis-based communities (Siboglinum sp., Lucinoma asapheus, Solemya elarraichensis) in Anastasya, sea-pen and burrowing megafauna communities (Funiculina quadrangularis, Kophobelemnon stelliferum, Pennatula aculeata, Isidella elongata) in Tarsis and sponge (Asconema, Petrosia, Haliclona, among others) and crinoid (mostly Leptometra phalangium) aggregations in Pipoca (González-García 2011; Rueda et al 2012b). Downloaded by [University of Sussex Library] at 07:03 03 February 2015…”

“…In the El Laberinto field (Spanish margin of the Gulf of Cádiz) three mud volcanoes are situated: Anastasya, Pipoca and Tarsis ( Figure 1). Some of these mud volcanoes seem to have lower seepage activity than those located in the Moroccan Margin and the presence of authigenic carbonates and the remains of chemosymbiotic species in some of them are indicators of past seepage activity (Somoza et al 2003;Rueda et al 2012b). The hard substrates composed of chimneys and slabs increases the bottom complexity and the development of different habitats, due to colonization by sessile species (sponges, gorgonians, coldwater corals) during periods of latent conditions (León et al 2007;Rueda et al 2012a).…”

“…Preliminary information on mud volcanoes of the Spanish margin such as those of El Laberinto has revealed the presence of different habitats and associated benthic communities, also including chemosymbiotic species (Siboglinum sp., Lucinoma asapheus, Solemya elarraichensis) (Anastasya), sea-pen and burrowing megafauna communities (Funiculina quadrangularis, Kophobelemnon stelliferum, Pennatula aculeata) (Tarsis and adjacent bottoms of Pipoca) and sponge aggregations (Asconema, Petrosia, Haliclona, among others) (Pipoca) (González-García 2011; Rueda et al 2012a;Rueda et al 2012b). Information on megafauna and fishing resources is in general scarce for the mud volcanoes of the Gulf of Cádiz, especially for those within Spanish waters.…”