Deep-sea benthic habitats modeling and mapping in a NE Atlantic seamount (Galicia Bank)

Abstract

This study presents the results of seafloor habitat identification and mapping of a NE Atlantic deep seamount. An "assemble first, predict later" approach has been followed to identify and map the benthic habitats of the Galicia Bank (NW Iberian). Biotic patterns inferred from the survey data have been used to drive the definition of benthic assemblages using multivariate tools. Eight assemblages, four hard substrates and four sedimentary ones, have been described from a matrix of structural species. Distribution of these assemblages was correlated with environmental factors (multibeam and backscatter data) using binomial GAMs. Finally, the distribution model of each assemblage was applied to produce continuous maps and pooled in a final map with the distribution of the main benthic habitats. Depth and substrate type are key factors when determining soft bottom communities, whereas rocky habitat distribution is mainly explained by rock slope and orientation. Enrichment by northern water masses (LSW) arriving to GB and possible zooplankton biomass increase at vertical-steep walls by "bottom trapping" can explain the higher diversity of habitat providing filter-feeders at slope rocky breaks. These results concerning vulnerable species and habitats, such as Lophelia and Madrepora communities and black and bamboo coral aggregations were the basis of the Spanish proposal of inclusion within the Natura 2000 network. The aim of the present study was to establish the scientific criteria needed for managing and protecting those environmental values.

Benthic habitat modelling and mapping as a conservation tool for marine protected areas: A seamount in the western Mediterranean

“…On the other hand, habitat 8 was the only habitat that was typified by sponges. Consistent with other studies on seamounts, sponges dwell close to steep escarpments (Davies et al, ; Serrano et al, ).…”

“…This finding is probably related to the diverse typologies recorded for habitat 9, which appeared on two different types of substrate: as reef on a coral framework in areas with high levels of sedimentation and as discrete colonies on rocky areas. These different morphologies of the same habitat have also been described from the Galicia Bank, which is another seamount that is part of the Spanish Natura 2000 network (Serrano et al, ).…”

“…Fournier, Barbet‐Massin, Rome, & Courchamp, ; Stirling, Scott, & Wright, ). Depth and slope have been cited among the main environmental predictors associated with the zonation of benthic communities on seamounts (De la Torriente et al, ; Du Preez, Curtis, & Clarke, ; McClain & Lundsten, ; Serrano et al, ). Distributed as depth‐regulated bands, these assemblages or habitat structure patterns are likely to be a combination of suitable ecological conditions and local recruitment processes (De la Torriente et al, ).…”

“…Brown & Blondel, ; Brown, Smith, Lawton, & Anderson, ). Consequently, backscatter is a valuable parameter as a high‐resolution proxy for benthic habitat identification (Collier & Brown, ; Serrano et al, ). Furthermore, some authors have obtained clear correlations between backscatter and grain size (Collier & Brown, ; De Falco et al, ; Goff, Olson, & Duncan, ), and the reflective strengths on the Seco de los Olivos seamount were used to identify the occurrence of carbonate coral mounds, well‐sorted bioclastic coarse sands, and coarser sediment fractions (Lo Iacono et al, ).…”

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

“…These oceanographic processes induced by the topography may provoke the enhancement of the primary production and retention of plankton (Xavier and van Soest, 2007;Denda et al, 2016), turning seamounts into ecosystems with high biomass, biodiversity and sometimes with a considerable level of endemism (Boehlert and Genin, 1987;Beckmann and Mohn, 2002;O'Hara, 2007;Pitcher et al, 2007;Clark et al, 2010;Miller and Gunasekera, 2017), which offer particularly good conditions for the settlement of benthic suspension feeders like corals and sponges (Koslow et al, 2001;Xavier and van Soest, 2007;O'Hara et al, 2008). Cold-water corals (CWC) have been described along the path of the Mediterranean Outflow Water (MOW) in several locations: at the Gazul mud volcano (Rueda et al, 2016), the Galicia Bank (e.g., Duineveld et al, 2004;Serrano et al, 2017), and the Porcupine Seabight (De Mol et al, 2002), among others.…”