Larval feeding of Chionodraco hamatus (Pisces, Channichthyidae) in the Ross Sea and its relation to environmental conditions

• Published in: Polar biology 2011, Vol.34 (1), p.127-137
• Main Authors: La Mesa, Mario, Catalano, Barbara, Greco, Silvestro
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Analysis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Channichthyidae; Chionodraco hamatus; Ecology; Environmental conditions; Environmental quality; Euphausia; Fundamental and applied biological sciences. Psychology; Larvae; Life Sciences; Marine; Microbiology; Oceanography; Original Paper; Particular ecosystems; Pisces; Plant Sciences; Pleuragramma antarcticum; Prey; Summer; Synecology; Thysanoessa macrura; Trematomus lepidorhinus; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Zoology
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-010-0866-0

Feeding habits of early life stages of the channichthyid Chionodraco hamatus were investigated on samples collected in the western Ross Sea in early summer of 1996 and 2004. The stomach content analysis was carried out on larval and postlarval specimens ranging from 14 to 39 mm SL. Unlike larvae and juveniles of other channichthyids, which elsewhere largely rely on early life stages of Antarctic krill or ice krill, no euphausiids were found in the stomach contents of C. hamatus, except for a single large individual of Thysanoessa macrura. In both years, dietary composition consisted almost exclusively of notothenioid fish larvae. Early larvae of Pleuragramma antarcticum overwhelmingly dominated the diet in terms of abundance, biomass and frequency of occurrence, accounting for 98.4% of the index of relative importance (IRI). Other fish larvae consumed occasionally in small amount were Trematomus lepidorhinus, T. scotti and C. hamatus itself. As a result, the feeding strategy of C. hamatus was considerably shifted toward specialization, relying on relatively few taxa of prey, each of them showing a high prey-specific abundance. Comparing both dietary composition and feeding strategy of C. hamatus in the two different sampling years, several differences were observed, probably due to different environmental conditions, mainly linked to a significant delay of ice retreat and formation of the Ross Sea polynya verified in the 2003-2004 summer season.