Comparative Feeding Ecology of Cardinalfishes (Apogonidae) at Toliara ReefMadagascar

摘要

Despite their importance incoral reef ecosystem function and trophodynamics, the trophic ecology of nocturnal shes( Apogonidae, Holocentridae, Pempheridae) is by far less studiedthan diurnal ones. The Apogonidae (cardinal shes) include mostly carnivorous species andevidence of trophic niche partitioning among sympatric cardinal shes is still limited. Thepresent study combines stomach contents and stable isotope analyses to investigate thefeeding ecology of an assemblage of eight cardinal shes from the Great Reef of Toliara (SWMadagascar). δ13C and δ15N of shes ranged between -17.49‰ and -10.03‰ and between 6.28‰and 10.74‰, respectively. Both stomach contents and stable isotopes showed that they feedon planktonic and benthic animal prey in various proportions. Previous studies were ableto group apogonids in di erent trophic categories but such a discrimination is not obvioushere. Large intra-speci c variation in the stomach contents and temporal variation in therelative contribution of prey to diet support that all apogonids should be considered asgeneralist, carnivorous shes. However the exploration of the isotopic space revealed aclear segregation of isotopic niches among species, suggesting a high level of resourcepartitioning within the assemblage. According to low inter-speci c variation in stomachcontent compositions, we argue that the di erences in isotopic niches could be driven byvariation in foraging locations ( microhabitat segregation) andphysiology among species. Our temporal datasets demonstrate that the trophic nichepartitioning among cardinal shes and the breadth of their isotopic niches are dynamic andchange across time. Factors driving this temporal variation need to be investigated infurther studies.