Structure of deep-sea pelagic fish assemblages in relation to the Mid-Atlantic Ridge (45°–50°N)

Abstract

Pelagic fishes from depths of 250 to 3200 m from 45 N to 50 N were sampled during a mid-Atlantic cruise in 1982. These clustered into 6 assemblages, which were related to the Mid-Atlantic Ridge, the continental shelf edge and oceanic habitats. Spatial distribution of clusters coincided with SST and surface chlorophyll patterns. Cluster distribution further coincided with published mid-depth hydrography indicating that hydrographic recirculation features were an important determinant of community structure. Over the ridge, Melamphaidae, Serrivomeridae, Stomiidae and Centrolophidae increased in abundance. Horizontally, the myctophid Benthosema glaciale indicated the transition from temperate-subtropical to temperate-subarctic waters. The gadid Micromesistius poutassou and the alepocephalid Xenodermichthys copei were characteristic species for the shallow shelf edge assemblage. Vertically, extended depth ranges were stated for assemblages above MAR and the southern leg, as indicated for the species Gonostoma bathyphilum, and Schedophilus medusophagus. This was further tested for the saccopharyngid Saccopharynx ampullaceus. The increase of gelatinous plankton feeders over the ridge, in particular for S. medusophagus, is discussed with respect to a probable increase of gelatinous plankton abundance in the area considered. An error model was developed to address the contamination problem with respect to non-closing devices. r

Structure and zonation of demersal fish assemblages off the Azores Archipelago (mid-Atlantic)

“…Williams et al (2001) among others (e.g. Fock et al 2004 in the Atlantic) also found a similar link between the local hydrographic features and the community structure of the demersal fish fauna of the continental slope of Western Australia. The conservative properties of slope water masses (e.g.…”

“…The relatively high abundance and biomass indices for this cluster might be related to the distribution of mesopelagic organisms. There is a continuous scattering layer at about 400 to 600 m depth in the region (Hareide & Garnes 2001, Fock et al 2004) along the MAR. This layer is composed of large densities of micronekton, planktonic organisms and various species of mesopelagic fishes.…”

Composition, distribution, and diversity of pelagic fishes around the Canary Islands, Eastern Central Atlantic

“…Depth is also the deciding factor in cephalopod assemblages along the Spanish Mediterranean coast (González & Sánchez 2002). Fock et al (2004) indicate that habitat structure in conjunction with physical and biological features is an important determinant of community structure. Benoit-Bird & Au (2006) found myctophids as the only animals in shallow waters of Hawaiian Islands, migrating actively with a striking horizontal component.…”

“…The structure of mesopelagic micronekton assemblages has been the subject of several investigations (Hulley 1992;González & Sánchez 2002;Fock et al 2004;Pusch et al 2004a), revealing a close relationship to physical and trophic conditions. The decreasing water depth around seamounts reduces density and diversity of mesopelagic fish (Pusch et al 2004b), which respond in different ways to the impingement with the demersal fauna (Porteiro & Sutton 2007).…”

Biodiversity Patterns and Processes on the Mid‐Atlantic Ridge

“…Pelagic and demersal nekton of the northern MAR were investigated by various historical expeditions that crossed the North Atlantic (see, for example, Murray & Hjort 1912 ;Schmidt 1931 ;T å ning 1944 ), and later by the Atlantic Zoogeography Program (Backus et al 1977 ), and German expeditions to the mid -ocean and seamounts (see, for example, Post 1987 ;Fock et al 2004 ). Information existed on the distribution of cephalopods at various specific locations in the Atlantic (Vecchione et al 2010 ), revealing general latitudinal patterns and information from isolated seamounts, but none were focused on the MAR.…”