How wave exposure, group size and habitat complexity influence foraging and population densities in fishes of the genus Halichoeres (Perciformes: Labridae) on tropical rocky shores José de Anchieta C. C. Nunes, Cláudio L. S. Sampaio & Francisco Barros Marine Biology International Journal on Life in Oceans and Coastal Waters ISSN 0025-3162 Mar Biol DOI 10.1007/s00227-013-2233-5 1 23 Your article is protected by copyright and all rights are held exclusively by Springer- Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Mar Biol DOI 10.1007/s00227-013-2233-5 ORIGINAL PAPER How wave exposure, group size and habitat complexity influence foraging and population densities in fishes of the genus Halichoeres (Perciformes: Labridae) on tropical rocky shores Jose´ de Anchieta C. C. Nunes • Cla´udio L. S. Sampaio • Francisco Barros Received: 7 September 2012 / Accepted: 26 March 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Wave exposure and habitat complexity have phases, showing that functional roles change in response to been used to explain variations in the distribution patterns ontogenetic shifts. and behavior of many reef fishes. This study analyzed the influence of both factors on density and foraging activity, and the influence of group size on foraging in three species Introduction of the genus Halichoeres (Labridae) on tropical rocky shores. It was shown that initial phases (IP) and terminal One of the most relevant questions regarding reef ecology phases (TP) Halichoeres, were influenced by wave expo- is how the environmental variables interfere in fish com- sure, although foraging in Halichoeres brasiliensis TP was munities structure (Jones and Syms 1998; Bellwood and not influenced by wave exposure. The IP in all three spe- Wainwright 2002). In fact, several studies have examined cies were positively associated with rugosity and algal the effect of both biotic and abiotic variables on the cover while the TP was positively associated with depth. structure of fish communities (Gladfelter and Gladfelter Habitat complexity also influences foraging in these spe- 1978, Luckhurst and Luckhurst 1978; Chabanet et al. 1997; cies. Group size influenced foraging activity, except in Ornellas and Coutinho 1998; Arbuto-Oropeza and Balart H. brasiliensis TP. We also found variations in micro- 2001; Ferreira et al. 2001). habitat patches used for foraging between species and According to Chaves and Monteiro-Neto (2009), habitat differences in the stomach contents between species and type and availability can influence the distribution, rich- ness, density and biomass of fish. Habitat complexity can therefore be an important factor explaining the richness and diversity of species, providing shelter from predators (Hi- Communicated by D. Goulet. xon and Beets 1993) and potentially changing competitive Electronic supplementary material The online version of this interactions and survival (Jones 1988; Syms and Jones article (doi:10.1007/s00227-013-2233-5) contains supplementary 2000). material, which is available to authorized users. Reef fish on tropical rocky shores have received rela- tively little attention (Ferreira et al. 2001), probably Jose´ de A. C. C. Nunes (&) Á F. Barros Laborato´rio de Ecologia Bentoˆnica, Universidade Federal da because in this region most studies are focused on coral Bahia, Rua Bara˜o de Geremoabo, s/n Ondina, Salvador, BA reefs, but despite their lower complexity, rocky shores and 40170-115, Brazil adjacent environments can also support a rich fauna and e-mail: [email protected] flora (Ferreira et al. 1998; Guimaraens and Coutinho 1996; Jose´ de A. C. C. Nunes Á F. Barros Ornellas and Coutinho 1998; Floeter et al. 2007). Programa de Po´s Graduac¸a˜o em Ecologia e Biomonitoramento, Understanding the effects of habitat structure on the Universidade Federal da Bahia, Salvador, BA, Brazil population density of fish is essential to assessing which variables are important (e.g., the influence of algae and C. L. S. Sampaio Departamento de Engenharia de Pesca, Unidade de Ensino corals on fish densities) and whether current predictions Penedo, Universidade Federal de Alagoas, Alagoas, Brazil can also be applied to different reef environments, such as 123 Author's personal copy Mar Biol rocky shores. Habitat complexity, as well as the composi- Wrasses exhibit a variety of behavioral characteristics tion of the substratum, can influence the behavior and and have a variety of preferred microhabitats for foraging, distribution of fish (Jones and Syms 1998, Floeter et al. but generally, there needs to be a positive relationship 2007, Krajewski et al. 2010). According to Krajewski et al. between swimming ability and home range used for for- (2010), distinctive structure and fauna associated with aging (Fulton and Belwood 2002; Jones 2002). The Hali- different types of substratum can offer different types of choeres genus is considered to be highly diverse and resources (e.g., prey and shelter) and can influence the widely distributed in the Atlantic Ocean (Rocha et al. activities of fish. 2010). These wrasse species are diurnal, exhibit opportu- Wave exposure is considered to be one of the key factors nistic behavior and feed on invertebrates (Randall 1967; in shaping coral reef fish assemblages, since hydrody- Sazima et al. 1998, 2005; Carvalho-Filho 1999). In Brazil, namics affects fish according to their various swimming there are eight species of this genus, five of which are abilities. Field and laboratory studies have investigated the endemic (Rocha et al. 2010; Froese and Pauly 2010). effects of water flow on the behavior and energy processes The relationships between habitat characteristics, for- of reef fish (Bellwood and Wainwright 2001; Fulton et al. aging activity and densities of Halichoeres species on 2001; Fulton and Belwood 2002). In general, they showed tropical rocky shores are poorly understood. Moreover, that when water flow increases, fish spend more time in trophic ecology and social behavior can change with refuges (Bellwood and Wainwright 2001; Fulton and Bel- development in these species (Lukoschek and McCormick wood 2002; Fulton et al. 2005; Floeter et al. 2007; Jo- 2001; Jones 2002; Bonaldo et al. 2006), but there has been hansen et al. 2007a, b). no study on ontogenetic shifts in the behavior of the Hal- Foraging behavior is a key aspect of habitat use by ichoeres species endemic to Brazil. animals, and fish are no exception (Fulton and Belwood This study examined the relationship between wave 2002). The optimal foraging theory considers the distri- exposure, group size (i.e., number of fish in a school), bution of prey within patches of microhabitat together with habitat complexity (rugosity, benthic cover) and depth on excursions between or within those patches to be important the foraging and densities of the wrasse species Halichoeres factors affecting foraging (MacArthur and Pianka 1966; poeyi (Steindachneir 1867), H. penrosei (Starks 1913) and Schoener 1971; Norberg 1977). Some studies have sug- H. brasiliensis (Bloch 1791) on tropical rocky shores in gested that foraging depends on the distribution and size of Brazil. The hypotheses were (1) that there would be a the patches of preferred habitat (Covich 1976; Fulton and negative relationship between wave exposure and foraging Belwood 2002). in these species in different ontogenetic phases, (2) that there Aggregation with other foragers is a common risk- would be a positive relationship between habitat complexity reduction strategy, allowing more time to be spent foraging and foraging in these species and (3) that there would be a without incurring a higher probability of becoming prey positive relationship between foraging activity and group (White and Warner 2007). Therefore, foraging in a group size. The variables which correlate with population densi- has been suggested as a way to reduce risk and to increase ties, preference to form schools, the preference for foraging the amount of information acquired regarding where to find patches and the diets of these species were also investigated. food and how long to stay on a patch of a certain quality (Stenberg and Persson 2005). Surgeonfish (Acanthuridae) and parrotfish (Labridae) forage more efficiently in large Materials and methods groups (Wolf 1987; Clifton 1991), but fish in high-density aggregations may forage less effectively or simply spend Study area less time foraging, and they may also experience interfer- ence competition while foraging (Buckel and Stoner 2004). The study was carried out on nine rocky shores located in The fishes of the Labridae family have a great variety of the city of Salvador, Bahia, Brazil (Fig. 1), which were body shapes and several morphological adaptations for assessed by means of snorkeling between September 2011 feeding and consequently have trophic versatility, which is and February 2012. The maximum depth was 6 m and the important in structuring reef communities (Randall 1967; hard substrata was composed predominantly of filamentous Hobson 1974; Deloach and Humann 1999). Although these algae, macroalgae and zoanthids (Palythoa caribaeorum fish have been the focus of studies in the Pacific Ocean and and Zoanthus sociatus). The black sea urchin Echinometra in the Caribbean (Thresher 1979; Bellwood and Wain- lucunter, ascidians and colonies of corals Favia gravida, wright 2001; Jones 2002, 2005, 2006), few such studies Montastrea cavernosa, Mussismilia hispida and Sideras- have been conducted in the South Atlantic (Sazima et al. trea spp. were also found.