title: The influence of fire-coral colony size and agonistic behaviour of territorial damselfish on associated coral reef fish communities.
abstract: Branching hydrocorals from the genus Millepora play an important ecological role in South Atlantic reefs, where branching scleractinian corals are absent. Previous studies have shown a high proportion of reef fish species using branching fire-coral colonies as shelter, breeding, and feeding sites. However, the effects of Millepora spp. colony size and how the agonistic behaviour of a competitive damselfish affect the associated reef fish community are still unknown. The present study examined how fire-coral colony volume and the presence of a highly territorial and aggressive damselfish (Brazilian endemic Stegastes fuscus) affects the reef fish community associated with the fire-coral Millepora alcicornis. M. alcicornis colonies were surveyed from September 2012 to April 2013 at Tamandaré Reefs off Northeast Brazil. Our results show that the abundance and richness of coral associated fish was positively correlated with M. alcicornis coral colony volume. Additionally, behaviour of S. fuscus, the most abundant reef fish species found associated with fire-coral colonies (almost 57% of the fish community), was also influenced by fire-coral colony volume. There was a clear trend of increased agonistic behaviour and feeding on coral polyps as colony volume increased. This trend was reversed for the non-occupational swimming category, which decreased as M. alcicornis colony volume increased. Behavioural ontogenetic changes were also detected for S. fuscus individuals. Juveniles mainly showed two distinct behaviours: sheltered on coral branches and feeding on coral polyps. In contrast, adults presented greater equitability among the behavioural categories, mostly non-occupational swimming around coral colonies and agonistic behaviour. Lastly, S. fuscus individuals actively defended fire-coral colonies from intruders. A large number of agonistic interactions occurred against potential food competitors, which were mainly roving herbivores, omnivores, and sessile invertebrate feeders. To our knowledge, the present study provides the first evidence that through habitat competition, the presence of S. fuscus may affect reef fish communities associated with M. alcicornis coral colonies. Our findings also indicate that S. fuscus uses M. alcicornis coral colonies as part of their territory for shelter and foraging. In conclusion, M. alcicornis fire-coral colonies are extremely important habitats for reef fishes and the size and presence of a territorial damselfish are relevant variables for associated reef fish community.
authors.affiliation: Departamento de Oceanografia, CTG, Universidade Federal de Pernambuco (UFPE), Av. Arquitetura, s/n, Cidade Universitária, Recife, PE 50670-901, Brazil.
authors.forename: Isabela Carolina Silva
authors.initials: IC
authors.lastname: Leal
authors.affiliation: Departamento de Oceanografia, CTG, Universidade Federal de Pernambuco (UFPE), Av. Arquitetura, s/n, Cidade Universitária, Recife, PE 50670-901, Brazil.
authors.forename: Maria Elisabeth
authors.initials: ME
authors.lastname: de Araújo
authors.affiliation: Departamento de Oceanografia, CTG, Universidade Federal de Pernambuco (UFPE), Av. Arquitetura, s/n, Cidade Universitária, Recife, PE 50670-901, Brazil.
authors.forename: Simone Rabelo
authors.initials: SR
authors.lastname: da Cunha
authors.affiliation: School of Marine and Tropical Biology, James Cook University - JCU, Townsville, QLD 4811, Australia. Electronic address: pedro.pereira@my.jcu.edu.au.
authors.forename: Pedro Henrique Cipresso
authors.initials: PH
authors.lastname: Pereira
mesh_terms: D000378:Agonistic Behavior / Q000502:physiology*; D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D001522:Behavior, Animal; D044822:Biodiversity; D057894:Coral Reefs; D005399:Fishes / Q000502:physiology*; D011156:Population Density
keywords: Competition; Coral-fish association; Habitat complexity; Millepora alcicornis; South Atlantic reefs; Stegastes fuscus