Depth zonation and latitudinal distribution of deep-sea scavenging demersal fishes of the Mid-Atlantic Ridge, 42 to 53°N

Abstract

Scavenging fishes of the Mid-Atlantic Ridge (MAR) were investigated using a baited autonomous lander equipped with a time-lapse camera between 924 and 3420 m water depth along 3 east-west transects at 42, 51 and 53° N across the MAR. We photographed 22 taxa at bait. Community structure analysis revealed 3 main assemblages, shallow (924 to 1198 m), intermediate (1569 to 2355 m) and deep (2869 to 3420 m), dominated by 3 species, Synaphobranchus kaupii, Antimora rostrata and Coryphaenoides (Nematonurus) armatus, respectively. Abyssal species in the axial valley region were C. armatus, Histiobranchus bathybius and Spectrunculus sp. Compared with continental margin regions A. rostrata were abundant and grew to a large size in the 2 northern transects, whereas S. kaupii were reduced in abundance and maximum depth of occurrence. The size, abundance and depth distribution of C. armatus was consistent with the hypothesis that these fish are part of a population mixing freely across the deep North Atlantic Basin. Temperature and latitude influenced distribution. (1) Five taxa were found only in the southern transect: Pseudotriakis microdon, Centroscymnus coelolepis, Simenchelys parasitica, Anguilliformes sp. and Lepidion 1 sp. (guentheri?). (2) Eight taxa were confined to the 2 northern transects: Bathyraja sp., Coryphaenoides 1 sp. (leptolepis?/mediterraneus?), Coryphaenoides 2 sp. (leptolepis?/mediterraneus?), Macrourus berglax, young macrourids, Lepidion 2 spp. (schmidti?), Anarhichas denticulatus and an unidentified zoarcid (Lycodonus n. sp.?/Lycenchelys alba?). (3) Eight species were ubiquitous across all 3 transects: Etmopterus princeps, Hydrolagus affinis, H. bathybius, S. kaupii, C. armatus, A. rostrata, Lepidion eques and Spectrunculus 1 sp..