caa a22 4500 606227806 CHVBK 20210128101200.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s10641-014-0334-8 doi (NATIONALLICENCE)springer-10.1007/s10641-014-0334-8 Agonistic behaviour and shoal composition of juvenile Diplodus sargus [Elektronische Daten] first field observations [Ana Gonçalves, Matheus Silva, Catarina Vendrell, Vitor Almada] Behavioural observations of juvenile Diplodus sargus in natural habitats were conducted to test whether agonistic interactions occur in natural circumstances and, if they do, in which context they happen. The level of aggression and the shoals composition were also compared between distinct natural habitats. Behavioural observations were also conducted in captivity, and the level of aggression was compared with the level recorded in natural conditions to investigate which factors may promote aggressive behaviours. The observations were performed at two sites in the Atlantic Portuguese shore: São Pedro do Estoril (38°41′N, 9°22′W) and Cabo Raso (38°42′N, 9°29′W) from early July to late August 2010 and from late July to early October 2011, respectively. In nature agonistic behaviours do occur, with a higher frequency in pools than in open areas. However, even the highest values observed in nature are significantly lower than those reported for captive conditions. Shoal composition also changed in different habitats, with more members and aggregates more compact in open areas. We suggested that the high levels of aggression observed in captive groups may be an artefact caused by very high densities in confined spaces and eventually by the accumulation of chemicals that are known to be released by stressed fish and can be detected by other conspecifics. The confinement imposed in captivity may also affect shoal composition limiting the number of members and inter-individual distances in each group. Springer Science+Business Media Dordrecht, 2014 Aggressive behaviour nationallicence Social structures nationallicence Intertidal habitats nationallicence Field observations nationallicence Sparidae nationallicence Gonçalves Ana Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut Silva Matheus Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut Vendrell Catarina Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut Almada Vitor Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut Environmental Biology of Fishes Springer Netherlands 98/4(2015-04-01), 1015-1021 0378-1909 98:4<1015 2015 98 10641 https://doi.org/10.1007/s10641-014-0334-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10641-014-0334-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gonçalves Ana Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut NATIONALLICENCE 700 1- Silva Matheus Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut NATIONALLICENCE 700 1- Vendrell Catarina Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut NATIONALLICENCE 700 1- Almada Vitor Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim do Tabaco 34, 1149-041, Lisboa, Portugal aut NATIONALLICENCE 773 0- Environmental Biology of Fishes Springer Netherlands 98/4(2015-04-01), 1015-1021 0378-1909 98:4<1015 2015 98 10641