Zoological Studies

Vol. 56, 2017

(update: 2017.4.27)

Comparative Feeding Ecology of Cardinalfishes (Apogonidae) at Toliara Reef, Madagascar

Bruno Frédérich1,2,*, Loïc N. Michel2,*, Esther Zaeytydt1, Roger Lingofo Bolaya1, Thierry Lavitra3, Eric Parmentier1, and Gilles Lepoint2

1Laboratoire de Morphologie Fonctionnelle et Evolutive, AFFISH Research Center, Université de Liège, Belgique. E-mail: bruno.frederich@ulg.ac.be (Frédérich); e.zaeytydt@gmail.com (Zaeytdt); rlingofo@gmail.com (Bolaya); e.parmentier@ulg.ac.be (Parmentier)
2Laboratoire d’Océanologie, MARE Center, Université de Liège, Belgique. E-mail: loicnmichel@gmail.com (Michel); g.lepoint@ulg.ac.be (Lepoint)
3Institut Halieutique et des Sciences Marines (IH.SM), Université de Tuléar, Madagascar. E-mail: lavitra_thierry@ihsm.mg

(Received 30 January 2017; Accepted 20 April, 2017; Communicated by Hin-Kiu Mok)

Bruno Frédérich, Loïc N. Michel, Esther Zaeytydt, Roger Lingofo Bolaya, Thierry Lavitra, Eric Parmentier, and Gilles Lepoint (2017) Despite their importance in coral reef ecosystem function and trophodynamics, the trophic ecology of nocturnal fishes (e.g. Apogonidae, Holocentridae, Pempheridae) is by far less studied than diurnal ones. The Apogonidae (cardinalfishes) include mostly carnivorous species and evidence of trophic niche partitioning among sympatric cardinalfishes is still limited. The present study combines stomach contents and stable isotope analyses to investigate the feeding ecology of an assemblage of eight cardinalfishes from the Great Reef of Toliara (SW Madagascar). d13C and d15N of fishes ranged between -17.49‰ and -10.03 ‰ and between 6.28‰ and 10.74‰, respectively. Both stomach contents and stable isotopes showed that they feed on planktonic and benthic animal prey in various proportions. Previous studies were able to group apogonids in different trophic categories but such a discrimination is not obvious here. Large intra-specific variation in the stomach contents and temporal variation in the relative contribution of prey to diet support that all apogonids should be considered as generalist, carnivorous fishes. However the exploration of the isotopic space revealed a clear segregation of isotopic niches among species, suggesting a high level of resource partitioning within the assemblage. According to low inter-specific variation in stomach content compositions, we argue that the differences in isotopic niches could be driven by variation in foraging locations (i.e. microhabitat segregation) and physiology among species. Our temporal datasets demonstrate that the trophic niche partitioning among cardinalfishes and the breadth of their isotopic niches are dynamic and change across time. Factors driving this temporal variation need to be investigated in further studies.

Key words: Apogonids, Stable isotopes, Isotopic niche, Diet, Western Indian Ocean.

*Correspondence: Bruno Frédérich and Loïc N. Michel contributed equally to this work. Tel: +3243665133.  Fax: +3243663715. E-mail: bruno.frederich@ulg.ac.be