ORIGINAL ARTICLE Exploring composition and behaviour of fish fauna by in situ observations in the Bari Canyon (Southern Adriatic Sea, Central Mediterranean) Gianfranco D’Onghia, Francesca Capezzuto, Angela Carluccio, Roberto Carlucci, Agnese Giove, Francesco Mastrototaro, Michele Panza, Letizia Sion, Angelo Tursi & Porzia Maiorano Department of Biology and CoNISMa LRU, University of Bari Aldo Moro, Bari,Italy Keywords Behaviour; canyon; feeding habit; fish fauna; Mediterranean. Correspondence Gianfranco D’Onghia, Department of Biology, University of Bari Aldo Moro – Via E. Orabona 4, 70125, Bari, Italy. E-mail: gianfranco.donghia@uniba.it Accepted: 8 February 2014 doi: 10.1111/maec.12162 Abstract Canyons play a fundamental role in enhancing the abundance and diversity of marine organisms through the transport of organic matter and food resources, the presence of complex physical habitats and the absence of trawl fishing. During four baited lander deployments carried out in the Bari Canyon (South- ern Adriatic Sea, Central Mediterranean), at depths of 443–788 m, about 43 h of video records were taken, for a total of 619,200 video frames. A total of 12 benthopelagic fish species (five chondrichthyes and seven osteichthyes) were identified. The blackspot seabream (Pagellus bogaraveo) was the most often observed fish species. The depth of 787 m represents a new depth record for this fish in the Adriatic Sea. Groups of up to 40 individuals of P. bogaraveo were attracted to the bait and were shown in single frames. The individuals were observed both exploring the area and feeding actively on the bait. The European conger (Conger conger) was recorded at each deployment. Clear scavenger behaviour was also observed in this teleost fish and in the shark Etmopterus spinax. The shark species Centrophorus granulosus and Hexanchus griseus, which are considered ‘vulnerable’ on the published IUCN Mediterra- nean Regional Red List, were also recorded but, although attracted by the bait, they were never seen feeding on it. Other fish species, harvested on fishing grounds, such as Merluccius merluccius, Helicolenus dactylopterus and Polyprion americanus, were also recorded. This study represents the first in situ documen- tation, at very low impact, of the fish fauna in the Bari Canyon, providing new insights into its small scale distribution and behaviour, the first in situ direct observation of the variable feeding behaviour of P. bogaraveo and its gregarious habits, as well as indicating that this canyon could act as a refuge area for species that are vulnerable to fishing on the open slope. Introduction Submarine canyons are complex structures capable of enhancing the heterogeneity of the slope and therefore play an important role in the functioning of the deep sea ecosystem (Danovaro et al. 2010; Wu  rtz 2012). In fact, canyons act as trapping areas for sediments and provide a direct pathway for sediment transport and dense water cascading from the continental shelf to the deep basin, enhancing the transport and availability of particles and organic matter (Turchetto et al. 2007; Tesi et al. 2008; Canals et al. 2009). The effect of canyons on local circula- tion can enhance the abundance and the diversity of mar- ine organisms, through the transport of sediment and phytodetritus and the presence of complex physical habi- tats (Vetter & Dayton 1998; Ramirez-Llodra et al. 2010). Higher macro- and megafauna biomass as well as spawn- ing and recruitment sites have been detected in the Medi- terranean canyons (e.g. Company et al. 2012; Wu  rtz 2012; Tecchio et al. 2013 and references therein). Marine Ecology (2014) 1–16 ª 2014 Blackwell Verlag GmbH 1 Marine Ecology. ISSN 0173-9565