Resumen de Deep-sea macrobenthic diversity and assemblages of “a selva” (NW Iberian peninsula): first approach from samples taken aboard r/v Sarmiento de Gamboa
Cristian Aldea, Guillermo Díaz Agras, Óscar García Álvarez, Juan Moreira, Marcelo Rodrigues, Ramiro Tato, Victoriano Urgorri, Jesús Souza Troncoso
The “A Selva” is a deep-sea area located in the Northwest of Galicia (43º30’N-44º15’N; 08º10’W- 09º10’W) including the continental shelf and slope with bottoms containing extensive carbonated hard grounds. This area possesses a high interest for both fishing ground and commercial routes, but the biological characteristics of their bottoms have not been extensively studied yet. The inaugural campaign for the R/V Sarmiento de Gamboa was carried out in July 2008 and was focused on that area, embracing several approaches, ranging from the study of the water-column to the ecology and systematics of the benthic fauna and the geology of those bottoms. In this report we present a first approach to the diversity and assemblages of the macrobenthic fauna. Samplings were done in 30 sites, at depths of about between 149 and 2,516 m, using a Naturalist dredge and an Agassiz trawl. Obtained animals up to 2 mm were assigned in their taxonomic groups and data were organized into matrices. Their diversity was evaluated by means of univariate measures (total abundance, number of taxa) and the most relatively abundant groups were estimated. Assemblages were determined by cluster analysis based on the Bray-Curtis coefficient. A total of 4,106 individuals belonging to 36 taxonomic groups were identified, being the most abundant Polychaeta, Ophiuroidea, Decapoda (Crustacea), Pteriomorphia (Bivalvia), Porifera, Hydrozoa, Hexacoralaria (Anthozoa) and Scaphopoda. The abundance and number of taxa showed great variations at different stations. The cluster analysis was able to separate five clusters which seem to be defined mainly by the bottom types and depth. These results allow us to evaluate the basic faunistic composition of “A Selva” and to serve as starting point for more detailed taxonomic and ecological investigations of benthic zoological groups.
