Megafaunal communities along a depth gradient on the tropical Brazilian continental margin

Abstract

The species composition, abundance and diversity patterns of the epibenthic megafauna and fish community from the tropical Brazilian continental margin were analysed based on 42 bottom trawls from the Campos Basin continental shelf and slope. Trawls were collected aboard R/V Gyre during autumn 2008 from depths of 13 to 2030 m. Overall, 452 species belonging to five main taxa were identified: teleosts (Actinopterygii) were represented by 196 species, crustaceans by 113 species and echinoderms by 108 species. These three groups contributed 92% to the 452 taxa. Several species (289) were recorded only once or twice, and the species accumulation curves showed no signs of being close to reaching asymptotic values. A tendency of increasing diversity and richness with depth was observed. Analysis of the trawls showed the existence of megafaunal assemblages significantly associated with depth and water mass. The shelf group (13–100 m) had subgroups associated with Coastal Water (CW) and South Atlantic Central Water (SACW). The upper-slope group (376–501 m) was found exclusively under the influence of SACW. The mid- and lower-slope group (978–2030 m) had two subgroups associated with the presence of Antarctic Intermediate Water and North Atlantic Deep Water. The 39 typifying species contributed 90% to the global similarity. Teleosts and squids greatly contributed to the within-group similarity over the shelf, while decapods, echinoids and galatheids contributed to the upper-slope assemblage. Deep-sea isopods and decapods mostly contributed to the mid- and lower-slope assemblages.

Key words:

• Abundance
• assemblages
• diversity
• megafaunal

Acknowledgements

The authors are grateful to the following taxonomists: Marcelo Rodrigues de Carvalho (Elasmobranchii), Dominique Didier (Holocephali), Fabio Di Dario (Clupeiformes), Marcelo Roberto Souto de Melo (Gadiformes), Luciano Gomes Fischer (Perciformes), Rodrigo Leão de Moura (Tetraodontidae), Celso Rodrigues Abreu Junior (Galatheidae), Elaine Albuquerque (Isopoda), Fernando Mantelatto (Paguridae), Ingrid Ávila da Costa (Serolidae), Irene de Azevedo Cardoso (Penaeidae), Joel Braga (Stomatopoda), Lucia de Siqueira Campos (Ophiuroidea and Holothuroidea), Renato Ventura (Crinoidea, Echinoidea and Asteroidea), and Valéria Veloso (Brachyura). We also thank two anonymous reviewers for providing helpful comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This study is part of a larger project entitled ‘HABITATS – Campos Basin Environmental Heterogeneity’ conducted by ‘CENPES/PETROBRAS’. PASC (302.392/2010-6), ASM and MH (309282/2011-0) are supported by CNPq. Financial support to MMM provided by FAPERJ (E-26/110.118/2010).

Editorial responsibility: Javier Sellanes