Diet and potential feeding overlap between Trichiurus lepturus (Osteichthyes: Perciformes) and Pontoporia blainvillei (Mammalia: Cetacea) in Northern Rio de Janeiro, Brazil

Abstract

ABSTRACT. This study describes the diet and assesses potential overlap in the feeding habits of Trichiurus lepturus Linnaeus, 1758 and Pontoporia blainvilleiGervais & D'Orbigny, 1844 in northern Rio de Janeiro, southeastern Brazil. Fishes were numerically dominant in both diets, followed by cephalopods for P. blainvillei and crustaceans for T. lepturus. Both predators move along similar coastal feeding areas in northern Rio de Janeiro, but our results indicate differences in their resource exploitation, what allows for their coexistence.

Mercury and stable isotopes (δ15N and δ13C) as tracers during the ontogeny of Trichiurus lepturus

“…C signatures suggest no seasonal changes in the fish feeding habits, which corroborates Bittar et al (2008) and Bittar & Di Beneditto (2009). The same feeding habits all year could reflect the prey availability in the study area.…”

“…During fish's development, the specimens can be separated into ontogenetic phases according to length and feeding habits: the juveniles (5-30 cm) that feed on planktonic microcrustaceans; the sub-adults (>30-70 cm) and small adults (>70-100 cm) that feed on pelagic macrozooplankton and juvenile fishes, and the adults (>100 cm) that feed on squids and fishes, including co-specifics (Martins et al, 2005). This species moves between estuarine and marine environments (Froese & Pauly, 2012) and adult specimens are considered top predators in marine food chains (Chiou et al, 2006;Bittar & Di Beneditto, 2009;Di Beneditto et al, 2012).…”

Prey consumed by Guiana dolphin Sotalia guianensis (Cetacea, Delphinidae) and franciscana dolphin Pontoporia blainvillei (Cetacea, Pontoporiidae) in an estuarine environment in southern Brazil

“…The Guiana dolphin diet exhibited higher richness than the franciscana diet. The number of preys varied along the distribution of these species in south and southeastern Atlantic (SantoS et al, 2002;gurjão et al, 2003;di Beneditto & SiCiLiano, 2007;Bittar & di Beneditto, 2009;daura-jorge et al, 2011) and could be related to changes in prey availability and accessibility (daniLeviCz et al, 2002;daura-jorge et al, 2011). Predation on abundant resources could characterize an opportunistic behaviour, following the definition of Begon et al (1996).…”

“…Literature information indicated that prey size for S. guianensis changes along its distribution, as recorder by panSard et al (2010) (mean 13.18 ± 8.85 cm) and daura-jorge et al (2011) (mean = 21.4 ± 21.2 cm). For P. blainvillei it seems that the species preys on fishes of smaller total length (rodriguez et al, 2002;Bittar & di Beneditto, 2009).…”

“…Published data about its diet was described in some areas of Argentina and Uruguay (fitCh & BrowneLL, 1971;rodríguez et al, 2002), as well as for the Brazilian coast (SantoS & haimoviCi, 2001;Bittar & di Beneditto, 2009). A review of prey species recorded for the franciscana can be found at daniLewiCz et al (2002).…”