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RESEARCH ARTICLE

Assemblage structure and trophic ecology of deep-sea demersal cephalopods in the Balearic basin (NW Mediterranean)

Emanuela Fanelli A B , Joan E. Cartes A and Vanesa Papiol A
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- Author Affiliations

A ICM-CSIC Institut de Cienciès del Mar, P.g Maritim de la Barceloneta 37-49, Barcelona 08003, Spain.

B Corresponding author. Email: efanelli@icm.csic.es

Marine and Freshwater Research 63(3) 264-274 https://doi.org/10.1071/MF11157
Submitted: 5 July 2011  Accepted: 17 November 2011   Published: 22 December 2011

Abstract

Despite the important ecological role of cephalopods in energy and material flow in marine ecosystems, they are poorly understood, particularly those inhabiting deep-sea bottoms below 800 m. To define cephalopod species assemblages from the upper to the lower slope, we conducted 13 oceanographic and trawl surveys in the Balearic basin (NW Mediterranean) in 1985–92 and 2007–10 at depths between 450 and 2200 m. Multivariate analysis suggests the existence of three assemblages on the upper (450–600 m), middle (650–1500 m) and lower (1600–2200 m) slopes. Although seasonal changes in species abundance and composition were evident, no significant variations in the assemblage structure were observed between the two time periods. Two main trophic pathways involving deep-sea cephalopods were apparent: species mainly linked to benthic resources and species mostly connected to the pelagic food web through active swimming and frequent vertical migrations. Accordingly, two environmental variables best explained the observed patterns: net primary production and river discharge. Phytoplankton availability controls the increase of zooplankton that influences the distribution and abundance of pelagic cephalopods. River discharge affects, in some instances with delays, transfer of organic matter to the benthic trophic pathway and thus to bottom-dwelling cephalopods.

Additional keywords: bathymetric distribution, diversity, food web, long-term changes.


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