Interspecific associations are common in complex environments such as coral reefs (Deloach, Reference Deloach1999), and following behaviour is the most common association in such environments, especially in the Brazilian coastal reefs and oceanic islands (Gasparini & Floeter, Reference Gasparini and Floeter2001; Gibran, Reference Gibran2002; Santos & Castro, Reference Santos and Castro2003; Sazima et al., Reference Sazima, Bonaldo, Krajewski and Sazima2005; Sazima & Grossman, Reference Sazima and Grossman2005; Gerhardinger et al., Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006; Krajewski et al., Reference Krajewski, Bonaldo, Sazima and Sazima2006; Sazima et al., Reference Sazima, Krajewski, Bonaldo and Guimarães2006; Sampaio et al., Reference Sampaio, Medeiros, Ilarri, Souza and Grempel2007).
The following behaviour is an association that occurs in shallow tropical waters and it involves diurnal predators, including a large variety of ‘nuclear species’. These species explore the substrate by disturbing soft bottoms or coral reef habitats exposing potential prey to opportunist or generalist species, known as ‘the followers’ (Strand, Reference Strand1988; Gibran, Reference Gibran2002; Sazima et al., Reference Sazima, Krajewski, Bonaldo and Guimarães2006).
According to previous studies concerning this behaviour, the association benefits the follower, which has access to prey usually unavailable and might increase feeding success or decrease susceptibility to predation (Diamond & Shpigel, Reference Diamant and Shpigel1985; Strand, Reference Strand1988; Deloach, Reference Deloach1999; Gerhardinger et al., Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006).
We report for the first time the twinspot bass, Serranus flaviventris (Cuvier, 1829) (Serranidae), acting as a follower of the goldspotted eel, Myrichthys ocellatus (Lesueur, 1825) (Ophichthidae), in the sand/mud bottom of Gamboa beach, Tinharé Island, Cairú, Bahia (13°23′s 038°55′W), between May and December 2005. Snorkelling observations and photographs where taken during daylight periods in shallow waters. We have used the focal animal methodology and recorded all occurrences and total length (TL) (visually estimated) on plastic sheets (Altman, Reference Altman1974).
The following behaviour between the twinspot bass and the eel was recorded only once, in 30 minutes of observations. At the encounter, the twinspot bass (~50 mm TL) was already following the nuclear eel (~400 mm TL). While the goldspotted eel was disturbing the substrate, by moving slowly on the bottom, the twinspot bass placed itself close to the eel (Figure 1) and frequently inspected the suspended particles during the period of observation.
Serranus flaviventris following Myrichthys ocellatus as it disturbs the substrate at Gamboa reef, Tinharé Island, Cairú, Bahia. (Photograph: Rodrigo Maia-Nogueira.)
Serranids are amongst the most curious and inquisitive marine fish (Gerhardinger et al., Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006). In Bahia State they have been observed in opportunistic behaviour. Coney (Cephalopholis fulva), rock hind (Epinephelus adscensionis), black grouper (Mycteroperca bonaci) and freckled soapfish (Rypticus bistrispinnus), were observed following the goldspotted eel in various coastal habitats, such as estuary, rocky and coral reefs. All individuals were juveniles, an exception was the freckled soapfish (Sampaio, Nunes & Maia-Nogueira, personal observation). Unlike other serranids along the Brazilian coast, which invest against their prey relentlessly (Gibran, Reference Gibran2002, Reference Gibran2007; Sazima & Grossman, Reference Sazima and Grossman2005; Gerhardinger et al., Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006), these serranids remained close to the eel most of the time, moving only when the latter moved away from it or when something else disturbed the sediment suspending it.
Associations such as the following behaviour between serranids and other animals are apparently common and widely distributed (Karplus,Reference Karplus1978; Diamant & Shpigel, Reference Diamant and Shpigel1985; Deloach, Reference Deloach1999; Gibran, Reference Gibran2002; Gerhardinger et al., Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006; Sazima et al., Reference Sazima, Krajewski, Bonaldo and Guimarães2006). In Brazil, some studies refer to other serranids acting as opportunist followers: Gibran (Reference Gibran2002, Reference Gibran2007) recorded interactions between the sand perch, Diplectrum formosum, and the pond perch, D. radiale, towards the nine-armed sea star, Luidia senegalensis, in the São Sebastião Channel, São Paulo, as well as an association between the coney, C. fulva, and the brittlestar Ophioderma sp. in the Fernando de Noronha Archipelago. At Todos os Santos and Camamu Bay, Diplectrum spp. was observed following the eyed flounder, Bothus ocellatus, and the inshore lizardfish, Synodus foetens, respectively (Sampaio & Nunes, personal observation). Gerhardinger et al. (Reference Gerhardinger, Hostim-Silva, Samagaia and Barreiros2006) have also described the following behaviour of a young dusky grouper, Epinephelus marginatus (Lowe, 1834), to the goldspotted eel M. ocellatus, in the Biological Reserve of Ilha do Arvoredo, Santa Catarina. In biogenic reefs, at Barra Grande de Camamu, Epinephelus adscensionis and C. fulva, were observed actively following octopuses, Octopus insularis (Leite & Haimovici, Reference Leite, Haimovici, Molina and Warnke2008) (Lewis, Nunes & Sampaio, personal observation). Only coney was registered following O. insularis in Fernando de Noronha Archipelago (Sazima et al., Reference Sazima, Krajewski, Bonaldo and Sazima2007). In addition, Sazima & Grossman (Reference Sazima and Grossman2005) have recorded a coney, C. fulva, following a flying gurnard, Dactylopterus volitans (Linnaeus, 1758), in Fernando de Noronha Archipelago. In all cases the small and opportunist serranids followed the nuclear species taking advantage of the exposed prey.
Recently, Sazima et al. (Reference Sazima, Krajewski, Bonaldo and Sazima2007) reviewed all species of reef fish acting as followers in Fernando de Noronha Archipelago, and the only serranid recorded in that revision was C. fulva of the 17 nuclear species, including the greater soapfish, Rypticus saponaceus.
This paper is the first published record of the genus Serranus acting as a follower of the goldspotted eel. It is likely that S. flaviventris is the smaller serranid performing this behaviour. Future studies would reveal new interspecific associations involving other small or juvenile serranids in Brazilian waters.
ACKNOWLEDGEMENTS
We would like to thank all members of Centro de Pesquisa e Conservação dos Ecossistemas Aquáticos (Biota Aquática) for comments on the manuscript. Environmental Solutions (SOMA) for support and to Alfredo de Carvalho-Filho for sending relevant literature. We would also like to thank the buddy divers: Antonio Molina, Bruno Lima de Menezes, Daniel Chequer Bressan, Daniel Lewis and Igor Leoandro Cardoso de Lima, and José Rodrigues Nogueira Neto, Leo Dutra (UNE), Angela Zanata (UFBA) and Laís Chaves (UFF) for the English review and useful comments. The authors appreciate the critical comments made by two anonymous referees.
