SHORT COMMUNICATION

First report of cleaning behaviour in white sea bream (Diplodus sargus)

David Abecasis* and Ana Rita Costa Abecasis

Centre of Marine Sciences (CCMAR), University of the Algarve, Campus de Gambelas, Faro,Portugal

(Received 24 June 2014; accepted 12 November 2014)

Several studies have reported the existence of ectoparasites in the stomachcontents of Diplodus sargus. The cleaning behaviour has, however, never beenpreviously observed for this species. In this short study, we report the first obser-vations of the cleaning behaviour of D. sargus. These observations were in twoyachting marinas, located in the Portuguese western coast between the monthsof April and August. The cleaning behaviour was only observed towards twoMugilidae species, Chelon labrosus and Mugil cephalus.

Keywords: cleaning behaviour; white seabream; Sparidae; Diplodus sargus;Mugilidae; Chelon labrosus; Mugil cephalus

Cleaning service, where the cleaner fish removes ectoparasites and dead or injuredtissue from the “client” fish is a symbiotic behaviour. While providing a food sourcefor the cleaner fish, this behaviour helps to maintain the health of the “client” fish(Côté 2000). Although this behaviour is most frequent and widely studied in coral reeffish (e. g. Cheney & Côté 2003; Stummer et al. 2004; Soares et al. 2010), it has alsobeen observed in temperate fish species (e. g. Henriques & Almada 1997; Arnal &Morand 2001; Weitzmann & Mercader 2012).

The most common cleaner fish species belong to the Gobiidae and Labridaefamilies, although occasional cleaners can also be found in other families (Côté 2000).In the Sparidae family, only young Diplodus argenteus (Krajewski 2007) and Diploduspuntazzo (Schofield et al. 2006) have been found to present occasional cleaningbehaviour. In this study, we present the first record of direct observation of cleaningbehaviour in another sparid species Diplodus sargus.

Observations of the cleaning behaviour took place at two distinct marinas in thewestern coast of Portugal, Tróia Marina and Oeiras Yachting Harbour (Figure 1).Sampling locations were visited randomly throughout 2013 between the months ofApril and August. Observations were only made during daylight with most being car-ried out during the first hours after sunrise for periods of up to 30 min. Behaviouralobservations were made by the authors, while carefully standing on the pontoons toavoid scaring fish or altering their behaviour. Video recording took place during someof the observations. Small D. sargus, with an estimated total length between 4 and8 cm, were frequently observed, close to the surface, cleaning Chelon labrosus andMugil cephalus. No particular area seemed to be targeted by the cleaning fish asinteractions were observed to occur on the host species head, flank and tail. Although

*Corresponding author. Email: dabecassis@ualg.pt

© 2014 Taylor & Francis

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several of the client fish specimens showed clear presence of the ectoparasites, we couldnot determine with certainty on what the cleaning fish were feeding. It could have beenmucus, dead skin or ectoparasites. In most occasions, the interaction lasted for veryshort periods of time, less than 15 s, and ended with the escape of the client.

Video 1. (Colour online) Single frame from video record with link to clip of cleaningbehaviour.

The first register of direct observation of cleaning behaviour in D. sargus isdescribed in this study. These observations support previous suggestions of the cleaningbehaviour of D. sargus. Although the direct observation of the cleaning behaviour ofD. sargus has not been reported previously, the occurrence of ectoparasites of the genusCaligus in the stomach contents of young D. sargus has been recorded, which suggeststhat D. sargus can be involved in cleaning behaviour (Rosecchi 1987; Mariani 2001).Further studies including stomach content analysis are needed in order to clarify thetype of food items ingested by the cleaning D. sargus in our study area. This type ofstudy would also help to clarify the nature of the relationship between D. sargus andthe host species: mutualism – if removing ectoparasites and dead skin; or parasitism –if removing healthy skin and mucus. A cleaning behaviour has been described for otherspecies of the Diplodus genus, namely for juvenile D. argenteus (Krajewski 2007) andfor D. puntazzo which were described cleaning sea turtles (Schofield et al. 2006).

In the present report, the cleaning behaviour was only observed for D. sargus,despite the presence of other Diplodus species in the study areas, such as Diplodusvulgaris. Moreover, only juvenile individuals of D. sargus exhibited cleaning behaviour,although adults were also frequently found in the area during the observations. This isalso in agreement with previous studies on the feeding habits of D. sargus, in which

72 D. Abecasis and A.R. Costa Abecasis

ectoparasites were only found in the stomachs of juvenile individuals (Rosecchi 1987;Sala & Ballesteros 1997; Mariani 2001; Figueiredo et al. 2005).

The cleaning activities of D. sargus were only directed towards two Mugillidae spe-cies: C. labrosus and M. cephalus. In this study, the cleaning interactions usually endedwith the “client” swimming vigorously away, suggesting that the juvenile D. sarguswere possibly also biting to remove the scales or mucus of Mugillidae species. The lim-ited number of client species observed in this study was also observed in previous workon the cleaning behaviour of D. argenteus, and interpreted as the result of poor identifi-cation of the cleaning activity of D. argenteus by fish clients given the lack of visualcues (Krajewski 2007). The fact that both D. sargus and D. argenteus lack the visualcharacteristics of common cleaner fish such as longitudinal striped colour patterns andsmall streamlined body size probably make the identification of these Diplodus spp. ascleaners more difficult by prospective clients (Stummer et al. 2004).

Studies on the feeding habitats of D. sargus have shown that ectoparasites, mainlyCaligus spp., were only found in the diets of young D. sargus inhabiting coastallagoons (Rosecchi 1987; Mariani 2001). Mariani (2001) suggested that this may berelated to the high fish density found in these habitats which could promote the bloomof ectoparasites. In turn, the latter could constitute an important food resource for youngschooling fish. In our study, the two study locations are very close to two large estua-rine areas, the Sado and Tagus estuaries, which are important nursery areas for manyfish species including D. sargus (Vinagre et al. 2010). During their settlement migra-tions from estuarine to coastal areas, some fish species use marinas as recruitment areas(Clynick 2006). The waters inside these man-made artificial structures are usuallysheltered and their intertidal assemblages are significantly different from rocky shores

Figure 1. Location of the Oeiras Yachting Harbour and Tróia Marina.

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(Bulleri & Chapman 2004). These differences can significantly affect the number andtype of prey items available, thus the juvenile D. sargus may be engaging in cleaningbehaviour to use ectoparasites as an alternative food source, as also observed in coastallagoons. To confirm these hypotheses, future studies should focus on the parasite loadof host species and compare it with other locations and also on the availability of otherfood sources.

The use of juvenile D. sargus to control ectoparasites in aquaculture should beinvestigated as suggested for some Labridae species in salmon farms (Skiftesvik et al.2013).

Supplemental material

The supplemental material for this paper is available at: http://dx.doi.org/10.1080/10236244.2014.990700

AcknowledgementsThe authors would like to thank F. Almada for some comments and suggestions. This study waspartially supported by the Portuguese Foundation for Science and Technology/Ministry of Educa-tion and Science (FCT/MCTES-MEC) through individual support by a postdoctoral grant to D.A.(SFRH/BPD/95334/2013).

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