Cephalopod paralarvae from the southeast–south Brazilian outer shelf and slope

Abstract

Cephalopod paralarvae were collected in the southeast–south Brazilian outer shelf and continental slope (24°–34°S) from 2009 to 2015 to evaluate their distribution and abundance in relation to water masses during Autumn and Spring seasons. A total of 801 paralarvae were caught with Bongo nets (500 µm mesh) in oblique tows at sample depths of up to 250 m. Fourteen families, 22 genera, and 15 species were identified. The most abundant families were Argonautidae (40.1%), Ommastrephidae (31%), and Enoploteuthidae (23.7%). The highest abundances were recorded on Autumn 2014 (667 ind 1000 m⁻³) and Argonauta nodosus was the most abundant species in the study area (437 ind 1000 m⁻³). Ommastrephes sp., Illex argentinus, and Abralia spp. paralarvae were also abundant (124, 131, and 135 ind 1000 m⁻³, respectively) during Spring 2009, 2010, and 2014, respectively. These species were collected under the influence of Tropical Water (TW), Subtropical Shelf Water (STSW), and South Atlantic Central Water (SACW). Illex argentinus and Ommastrephes sp. paralarvae occupy different niches. The latter was significantly more abundant in the northern area, in TW and TW + SACW water masses, while I. argentinus was more abundant in the outer southern shelf, in the STSW. This is the first study evaluating the composition, distribution, and abundance of cephalopod paralarvae in the study area, while also providing the first record of Bolitaena pygmaea, Egea inermis, Pterygioteuthis sp., and Promachoteuthis sp. paralarvae.