Early life cycle of cephalopods in relation to the major oceanographic features of the southwest Atlantic Ocean

Cephalopod paralarvae and juveniles were sampled with RMT8 and Bongo nets during 2 cruises of the MV 'Falklands Protector' in the southwest Atlantic Ocean in October/November 1990 and 1991. Each cruise had 2 phases, a northern phase over the Patagonian Shelf edge and adjacent waters, and a southern phase over the shelf around the Falkland Islands. Vertical temperature profiles were used to identify the major fronts and water masses. The subtropical water of the Brazil Current was characterized by the tropical/subtropical Abraliopsis pfefferi and Histioteuthis corona corona, the subtropical/subantarctic H. atlantica and the widespread Taningia danae, species of Brachioteuthis, Chiroteuthis and Galiteuthis, a single specimen of Illex argentinus and an ommastrephid rhynchoteuthion type B. The subantarctic surface water of the Falkland Current contained the richest assemblage of species and was characterised by the subtropical/subantarctic H. atlantica, the subantarctic Batoteuthis skolops, H. eltaninae, H. macrohista and the subantarctic/antarctic Gonatus antarcticus. With the exception of some small Gonatus antarcticus, the polar frontal zone water of the Falkland Current was relatively poor in species. The Falkland Islands Shelf yielded Loligo gahi, Gonatus antarcticus, Martialia hyadesi, Moroteuthis knipovitchi, Batoteuthis skolops, Semirossia patagonica and an Octopus sp. The data provide new information on the life cycles of Martialia hyadesi and Gonatus antarcticus and are consistent with the view that L. gahi reproduces in shallow water around the Falkland Islands with 1 major brood spawning in the late austral winter.

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