Physical Connectivity Between the NE Atlantic Seamounts

Abstract

Within the Portuguese Exclusive Economic Zone, the Great Meteor and Madeira-Tore complexes are highly productive areas, which are likely to be classified as marine protected areas (MPAs) due to their ecological vulnerability. This was the main focus of the BIOMETORE project and, framed on it, the aim of the present study was to investigate the physical connectivity between both seamount complexes. Using the HYbrid Coordinate Ocean Model coupled with the Connectivity Modeling System (CMS) (a Lagrangian tool), a series of experiments was conducted in order to determine the influence of the main oceanographic phenomena governing the area in: (i) the origin of the particles that reach each complex, (ii) their capacity to capture and retain incoming particles, and (iii) the physical connectivity between them as well as the intra-connectivity within each seamount system. Due to the geographical location of both groups of seamounts, the Azores Current (AzC) and its associated eddies were identified as the main transport pathways, its influence being stronger at intermediate waters and decreasing with depth. Notwithstanding, the Great Meteor and the Madeira-Tore were mainly affected by the AzC southward and eastward branches, respectively, resulting in a non-significant connectivity between the two groups. Meanwhile, the inter-connectivity between seamounts slightly varied with depth at the Great Meteor complex while increasing at Madeira-Tore. In addition, the Plateau, Irving, and Cruiser (PIC) seamounts from the Great Meteor complex and Gorringe and Coral from the Madeira-Tore complex proved to incorporate the regional connectivity routes. Although containing the three smallest seamounts, Madeira-Tore showed the higher capturing capacity per square kilometer, highlighting the influence of the "sticky water effect." In the Great Meteor complex, the "seamount effect" seems to be the main phenomenon responsible for the greater retention and self-recruitment abilities of these seamounts. The presented results provide valuable information for the design of a MPA to preserve these vulnerable habitats.

Morphospecies and molecular diversity of ‘lace corals’: the genus Reteporella (Bryozoa: Cheilostomatida) in the central North Atlantic Azores Archipelago

“…5 in São Miguel). Being the easternmost islands of the archipelago, it is not surprising that high diversity is encountered here, as under the eastbound sea-surface circulation, bryozoan larvae/rafts are likely to divert to this area of the archipelago [66,[77][78][79].…”

“…In Flores only one species (R. atlantica) was present, but this low diversity can be an artefact of the sampling at only one site and depth (150 m). More species are likely to occur at other bathymetries, although an overall lower diversity would not be surprising considering the westernmost position of this island in the archipelago, which, under the eastbound circulation regime, does not favour retention of particles, and thus larvae, in the area [66,77,79].…”

“…Reteporella populations in distant islands that exceed the range that larvae can travel in the water column prior to successful settlement and metamorphosis, may thus be subject to prolonged evolution in isolation. Rare chance events such as strong storms or hurricanes [80,81], or the formation of eddies [77,79], may enhance sea-surface current speed or even induce a change in current direction, and thus connect separated populations or bring together distinct species [29].…”

Diversity, Distribution and Phylogenetic Relationships of Deep-Sea Lithistids (Porifera, Heteroscleromorpha) of the Azores Archipelago

“…The large-scale circulation of the temperate northeast Atlantic is dominated 2) 11 ( 5) 3 ( 1) 16 ( 7) 6 ( 3) 3 ( 0 by the Azores Current (AzC) that flows eastwards toward the Iberian margin (Carracedo et al, 2014). Importantly, the AzC southward and eastward branches have been identified as an important transport pathway between the Azores archipelago and the oceanic seamounts of the Great Meteor complex and the Lusitanian seamounts, respectively (Lima et al, 2020). The AzC therefore provides the physical connectivity needed for the dispersal of sponge larvae between these regions.…”